Science.gov

Sample records for affecting image quality

  1. Parameters affecting image quality with Time-Resolved Optical Integrative Neutron (TRION) detector

    NASA Astrophysics Data System (ADS)

    Mor, I.; Vartsky, D.; Feldman, G.; Dangendorf, V.; Bar, D.; Goldberg, M. B.; Tittelmeier, K.; Bromberger, B.; Weierganz, M.; Brandis, M.

    2011-06-01

    We have investigated by simulations and experimentally the parameters that affect image quality (contrast and spatial-resolution) of the fast neutron TRION detector. A scintillating fiber screen with 0.5×0.5 mm 2 square fibers, few centimeters thick, provides superior spatial-resolution to that of a slab scintillator of the same thickness. A detailed calculation of the neutron interaction processes that influence the point-spread function (PSF) in the scintillating screen has been performed using the GEANT 3.21 code. The calculations showed that neutron scattering within the screen accounts for a significant loss of image contrast. The factors that limit the spatial-resolution of the image are the cross-sectional scintillating-fiber dimensions within the screen and the spatial response of the image-intensifier. A deconvolution method has been applied for restoring the contrast and the spatial-resolution of the fast neutron image.

  2. Female Genital Dialogues: Female Genital Self-Image, Sexual Dysfunction, and Quality of Life in Patients With Vitiligo With and Without Genital Affection.

    PubMed

    Sarhan, Deena; Mohammed, Ghada F A; Gomaa, Amal H A; Eyada, Moustafa M K

    2016-01-01

    Vitiligo has a major effect on sexual health because of the disfiguring skin lesions affecting self-image and self-esteem. However, this topic has not explored. This article aimed to assess the effect of vitiligo on genital self-image, sexual function, and quality of life in female patients. This cross-sectional study included 50 sexually active women with vitiligo and 25 women without vitiligo. All participants subjected to full history taking and examination. Extent of vitiligo was assessed with the Vitiligo Area Scoring Index score, sexual function with the Female Sexual Function Index, genital self-image with Female Genital Self-Image Score and quality of life with the Dermatology Life Quality Index questionnaires. The main outcome measures were correlation between Vitiligo Area Scoring Index, Female Genital Self-Image Score, Female Sexual Function Index, and Dermatology Life Quality Index domains was determined using t test and Pearson correlation. This study revealed a negative correlation between the Vitiligo Area Scoring Index score and sexual satisfaction. Vitiligo Area Scoring Index and Dermatology Life Quality Index score was significantly correlated with Arabic Version of the Female Genital Self-Image Score alone and with Arabic Version of the Female Sexual Functioning Index alone and with both the Arabic Version of the Female Genital Self-Image Score and the Arabic Version of the Female Sexual Functioning Index (p <.05). Sexual and psychological assessment of patients with vitiligo is imperative to improve outcomes and increase patients' compliance with treatment. PMID:25650731

  3. Retention of 99mTc-DMSA(III) and 99mTc-nanocolloid in different syringes affects imaging quality.

    PubMed

    Bauwens, Matthias; Pooters, Ivo; van der Pol, Jochen; Mottaghy, Felix M; van Kroonenburgh, Marinus

    2014-04-01

    (99m)Tc-dimercaptosuccinic acid [DMSA(III)] and colloidal human serum albumin ((99m)Tc-nanocolloid) are widely used radiopharmaceuticals. Recently, in our institution we encountered image quality problems in DMSA scans after changing the brand of syringes we were using, which triggered us to look into the adsorption properties of syringes from different brands for (99m)Tc-DMSA(III) and (99m)Tc-nanocolloid. We also describe a clinical case in which adsorption of (99m)Tc-DMSA(III) caused inferior imaging quality. DMSA and nanocolloid were labeled with (99m)Tc following manufacturer guidelines. After synthesis, syringes with (99m)Tc-DMSA(III) and (99m)Tc-nanocolloid were stored for 15, 30, 60, and 120 min. We evaluated Luer Lock syringes manufactured by different brands such as Artsana, Henke-Sass-Wolf, B. Braun Medical N.V., CODAN Medizinische Geräte GmbH & Co KG, Becton Dickinson and Company, and Terumo Europe. Adsorption of (99m)Tc-DMSA(III) and (99m)Tc-nanocolloid was acceptably low for all syringes (<13%), except for two brands with (99m)Tc-DMSA(III) adsorption rates of 36 and 30%, respectively, and for one brand with a (99m)Tc-nanocolloid adsorption rate of 27%. Adsorption of (99m)Tc-DMSA(III) and (99m)Tc-nanocolloid reaches critical levels in syringes produced by two brands, potentially causing poor image quality--for example, in DMSA scans using pediatric radiopharmaceutical doses. It is advised to check the compatibility of any radiopharmaceutical with syringes as an integral part of the quality assurance program. PMID:24569706

  4. Factors Affecting Medical Service Quality

    PubMed Central

    MOSADEGHRAD, Ali Mohammad

    2014-01-01

    Abstract Background A better understanding of factors influencing quality of medical service can pinpoint better strategies for quality assurance in medical services. This study aimed to identify factors affecting the quality of medical services provided by Iranian physicians. Methods Exploratory in-depth individual interviews were conducted with sixty-four physicians working in various medical institutions in Iran. Results Individual, organizational and environmental factors enhance or inhibit the quality of medical services. Quality of medical services depends on the personal factors of the physician and patient, and factors pertaining to the healthcare setting and the broader environment. Conclusion Differences in internal and external factors such as availability of resources, patient cooperation and collaboration among providers affect the quality of medical services and patient outcomes. Supportive leadership, proper planning, education and training and effective management of resources and processes improve the quality of medical services. This article contributes to healthcare theory and practice by developing a conceptual framework for understanding factors that influence medical services quality. PMID:26060745

  5. TV or not TV? Does the immediacy of viewing images of a momentous news event affect the quality and stability of flashbulb memories?

    PubMed

    Schaefer, Evelyn G; Halldorson, Michael K; Dizon-Reynante, Cheryl

    2011-04-01

    The flashbulb accounts of 38 participants concerning the September 11th 2001 terrorist attack reported at both 28 hours and 6 months following the event were examined for quantity, quality, and consistency as a function of the time lapse between first learning of the event and initial viewing of media images. The flashbulb accounts of those who reported seeing images at least an hour after learning of the event differed qualitatively, but not quantitatively, from accounts of participants who reported seeing images at the same time as or within minutes of learning of the event. Delayed viewing of images resulted in less elaborate and generally less consistent accounts across the 6-month interval. The results are discussed in terms of factors affecting flashbulb memory formation and individual differences in connectedness to the event. PMID:21500086

  6. Image Enhancement, Image Quality, and Noise

    NASA Technical Reports Server (NTRS)

    Rahman, Zia-ur; Jobson, Daniel J.; Woodell, Glenn A.; Hines, Glenn D.

    2005-01-01

    The Multiscale Retinex With Color Restoration (MSRCR) is a non-linear image enhancement algorithm that provides simultaneous dynamic range compression, color constancy and rendition. The overall impact is to brighten up areas of poor contrast/lightness but not at the expense of saturating areas of good contrast/brightness. The downside is that with the poor signal-to-noise ratio that most image acquisition devices have in dark regions, noise can also be greatly enhanced thus affecting overall image quality. In this paper, we will discuss the impact of the MSRCR on the overall quality of an enhanced image as a function of the strength of shadows in an image, and as a function of the root-mean-square (RMS) signal-to-noise (SNR) ratio of the image.

  7. Social image quality

    NASA Astrophysics Data System (ADS)

    Qiu, Guoping; Kheiri, Ahmed

    2011-01-01

    Current subjective image quality assessments have been developed in the laboratory environments, under controlledconditions, and are dependent on the participation of limited numbers of observers. In this research, with the help of Web 2.0 and social media technology, a new method for building a subjective image quality metric has been developed where the observers are the Internet users. A website with a simple user interface that enables Internet users from anywhere at any time to vote for a better quality version of a pair of the same image has been constructed. Users' votes are recorded and used to rank the images according to their perceived visual qualities. We have developed three rank aggregation algorithms to process the recorded pair comparison data, the first uses a naive approach, the second employs a Condorcet method, and the third uses the Dykstra's extension of Bradley-Terry method. The website has been collecting data for about three months and has accumulated over 10,000 votes at the time of writing this paper. Results show that the Internet and its allied technologies such as crowdsourcing offer a promising new paradigm for image and video quality assessment where hundreds of thousands of Internet users can contribute to building more robust image quality metrics. We have made Internet user generated social image quality (SIQ) data of a public image database available online (http://www.hdri.cs.nott.ac.uk/siq/) to provide the image quality research community with a new source of ground truth data. The website continues to collect votes and will include more public image databases and will also be extended to include videos to collect social video quality (SVQ) data. All data will be public available on the website in due course.

  8. SU-E-J-28: Gantry Speed Significantly Affects Image Quality and Imaging Dose for 4D Cone-Beam Computed Tomography On the Varian Edge Platform

    SciTech Connect

    Santoso, A; Song, K; Gardner, S; Chetty, I; Wen, N

    2015-06-15

    Purpose: 4D-CBCT facilitates assessment of tumor motion at treatment position. We investigated the effect of gantry speed on 4D-CBCT image quality and dose using the Varian Edge On-Board Imager (OBI). Methods: A thoracic protocol was designed using a 125 kVp spectrum. Image quality parameters were obtained via 4D acquisition using a Catphan phantom with a gating system. A sinusoidal waveform was executed with a five second period and superior-inferior motion. 4D-CBCT scans were sorted into 4 and 10 phases. Image quality metrics included spatial resolution, contrast-to-noise ratio (CNR), uniformity index (UI), Hounsfield unit (HU) sensitivity, and RMS error (RMSE) of motion amplitude. Dosimetry was accomplished using Gafchromic XR-QA2 films within a CIRS Thorax phantom. This was placed on the gating phantom using the same motion waveform. Results: High contrast resolution decreased linearly from 5.93 to 4.18 lp/cm, 6.54 to 4.18 lp/cm, and 5.19 to 3.91 lp/cm for averaged, 4 phase, and 10 phase 4DCBCT volumes respectively as gantry speed increased from 1.0 to 6.0 degs/sec. CNRs decreased linearly from 4.80 to 1.82 as the gantry speed increased from 1.0 to 6.0 degs/sec, respectively. No significant variations in UIs, HU sensitivities, or RMSEs were observed with variable gantry speed. Ion chamber measurements compared to film yielded small percent differences in plastic water regions (0.1–9.6%), larger percent differences in lung equivalent regions (7.5–34.8%), and significantly larger percent differences in bone equivalent regions (119.1–137.3%). Ion chamber measurements decreased from 17.29 to 2.89 cGy with increasing gantry speed from 1.0 to 6.0 degs/sec. Conclusion: Maintaining technique factors while changing gantry speed changes the number of projections used for reconstruction. Increasing the number of projections by decreasing gantry speed decreases noise, however, dose is increased. The future of 4DCBCT’s clinical utility relies on further

  9. Wavelet based image quality self measurements

    NASA Astrophysics Data System (ADS)

    Al-Jawad, Naseer; Jassim, Sabah

    2010-04-01

    Noise in general is considered to be degradation in image quality. Moreover image quality is measured based on the appearance of the image edges and their clarity. Most of the applications performance is affected by image quality and level of different types of degradation. In general measuring image quality and identifying the type of noise or degradation is considered to be a key factor in raising the applications performance, this task can be very challenging. Wavelet transform now a days, is widely used in different applications. These applications are mostly benefiting from the wavelet localisation in the frequency domain. The coefficients of the high frequency sub-bands in wavelet domain are represented by Laplace histogram. In this paper we are proposing to use the Laplace distribution histogram to measure the image quality and also to identify the type of degradation affecting the given image. Image quality and the level of degradation are mostly measured using a reference image with reasonable quality. The discussed Laplace distribution histogram provides a self testing measurement for the quality of the image. This measurement is based on constructing the theoretical Laplace distribution histogram of the high frequency wavelet sub-band. This construction is based on the actual standard deviation, then to be compared with the actual Laplace distribution histogram. The comparison is performed using histogram intersection method. All the experiments are performed using the extended Yale database.

  10. JPEG2000 still image coding quality.

    PubMed

    Chen, Tzong-Jer; Lin, Sheng-Chieh; Lin, You-Chen; Cheng, Ren-Gui; Lin, Li-Hui; Wu, Wei

    2013-10-01

    This work demonstrates the image qualities between two popular JPEG2000 programs. Two medical image compression algorithms are both coded using JPEG2000, but they are different regarding the interface, convenience, speed of computation, and their characteristic options influenced by the encoder, quantization, tiling, etc. The differences in image quality and compression ratio are also affected by the modality and compression algorithm implementation. Do they provide the same quality? The qualities of compressed medical images from two image compression programs named Apollo and JJ2000 were evaluated extensively using objective metrics. These algorithms were applied to three medical image modalities at various compression ratios ranging from 10:1 to 100:1. Following that, the quality of the reconstructed images was evaluated using five objective metrics. The Spearman rank correlation coefficients were measured under every metric in the two programs. We found that JJ2000 and Apollo exhibited indistinguishable image quality for all images evaluated using the above five metrics (r > 0.98, p < 0.001). It can be concluded that the image quality of the JJ2000 and Apollo algorithms is statistically equivalent for medical image compression. PMID:23589187

  11. Cognitive issues in image quality measurement

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib

    2001-01-01

    Designers of imaging systems, image processing algorithms, etc., usually take for granted that methods for assessing perceived image quality produce unbiased estimates of the viewers' quality impression. Quality judgments, however, are affected by the judgment strategies induced by the experimental procedures. In this paper the results of two experiments are presented illustrating the influence judgment strategies can have on quality judgments. The first experiment concerns contextual effects due to the composition of the stimulus sets. Subjects assessed the sharpness of two differently composed sets of blurred versions of one static image. The sharpness judgments for the blurred images present in both stimulus sets were found to be dependent on the composition of the set as well as the scaling technique employed. In the second experiment subjects assessed either the overall quality or the overall impairment of manipulated and standard JPEG-coded images containing two main artifacts. The results indicate a systematic different between the quality and impairment judgments that could be interpreted as instruction-based different weighting of the two artifacts. Again, some influence of scaling techniques was observed. The results of both experiments underscore the important role judgment strategies play in the psychophysical evaluation of image quality. Ignoring this influence on quality judgments may lead to invalid conclusions about the viewers' impression of image quality.

  12. Evaluation of image quality

    NASA Technical Reports Server (NTRS)

    Pavel, M.

    1993-01-01

    This presentation outlines in viewgraph format a general approach to the evaluation of display system quality for aviation applications. This approach is based on the assumption that it is possible to develop a model of the display which captures most of the significant properties of the display. The display characteristics should include spatial and temporal resolution, intensity quantizing effects, spatial sampling, delays, etc. The model must be sufficiently well specified to permit generation of stimuli that simulate the output of the display system. The first step in the evaluation of display quality is an analysis of the tasks to be performed using the display. Thus, for example, if a display is used by a pilot during a final approach, the aesthetic aspects of the display may be less relevant than its dynamic characteristics. The opposite task requirements may apply to imaging systems used for displaying navigation charts. Thus, display quality is defined with regard to one or more tasks. Given a set of relevant tasks, there are many ways to approach display evaluation. The range of evaluation approaches includes visual inspection, rapid evaluation, part-task simulation, and full mission simulation. The work described is focused on two complementary approaches to rapid evaluation. The first approach is based on a model of the human visual system. A model of the human visual system is used to predict the performance of the selected tasks. The model-based evaluation approach permits very rapid and inexpensive evaluation of various design decisions. The second rapid evaluation approach employs specifically designed critical tests that embody many important characteristics of actual tasks. These are used in situations where a validated model is not available. These rapid evaluation tests are being implemented in a workstation environment.

  13. Optimization of synthetic aperture image quality

    NASA Astrophysics Data System (ADS)

    Moshavegh, Ramin; Jensen, Jonas; Villagomez-Hoyos, Carlos A.; Stuart, Matthias B.; Hemmsen, Martin Christian; Jensen, Jørgen Arendt

    2016-04-01

    Synthetic Aperture (SA) imaging produces high-quality images and velocity estimates of both slow and fast flow at high frame rates. However, grating lobe artifacts can appear both in transmission and reception. These affect the image quality and the frame rate. Therefore optimization of parameters effecting the image quality of SA is of great importance, and this paper proposes an advanced procedure for optimizing the parameters essential for acquiring an optimal image quality, while generating high resolution SA images. Optimization of the image quality is mainly performed based on measures such as F-number, number of emissions and the aperture size. They are considered to be the most contributing acquisition factors in the quality of the high resolution images in SA. Therefore, the performance of image quality is quantified in terms of full-width at half maximum (FWHM) and the cystic resolution (CTR). The results of the study showed that SA imaging with only 32 emissions and maximum sweep angle of 22 degrees yields a very good image quality compared with using 256 emissions and the full aperture size. Therefore the number of emissions and the maximum sweep angle in the SA can be optimized to reach a reasonably good performance, and to increase the frame rate by lowering the required number of emissions. All the measurements are performed using the experimental SARUS scanner connected to a λ/2-pitch transducer. A wire phantom and a tissue mimicking phantom containing anechoic cysts are scanned using the optimized parameters for the transducer. Measurements coincide with simulations.

  14. Factors affecting enhanced video quality preferences

    PubMed Central

    Satgunam, PremNandhini; Woods, Russell L; Bronstad, P Matthew; Peli, Eli

    2013-01-01

    The development of video quality metrics requires methods for measuring perceived video quality. Most such metrics are designed and tested using databases of images degraded by compression and scored using opinion ratings. We studied video quality preferences for enhanced images of normally-sighted participants using the method of paired comparisons with a thorough statistical analysis. Participants (n=40) made pair-wise comparisons of high definition (HD) video clips enhanced at four different levels using a commercially available enhancement device. Perceptual scales were computed with binary logistic regression to estimate preferences for each level and to provide statistical inference of the differences among levels and the impact of other variables. While moderate preference for enhanced videos was found, two unexpected effects were also uncovered: (1) Participants could be broadly classified into two groups: those who preferred enhancement ("Sharp") and those who disliked enhancement ("Smooth"). (2) Enhancement preferences depended on video content, particularly for human faces to be enhanced less. The results suggest that algorithms to evaluate image quality (at least for enhancement) may need to be adjusted or applied differentially based on video content and viewer preferences. The possible impact of similar effects on image quality of compressed video needs to be evaluated. PMID:24107400

  15. Retinal Image Quality During Accommodation

    PubMed Central

    López-Gil, N.; Martin, J.; Liu, T.; Bradley, A.; Díaz-Muñoz, D.; Thibos, L.

    2013-01-01

    Purpose We asked if retinal image quality is maximum during accommodation, or sub-optimal due to accommodative error, when subjects perform an acuity task. Methods Subjects viewed a monochromatic (552nm), high-contrast letter target placed at various viewing distances. Wavefront aberrations of the accommodating eye were measured near the endpoint of an acuity staircase paradigm. Refractive state, defined as the optimum target vergence for maximising retinal image quality, was computed by through-focus wavefront analysis to find the power of the virtual correcting lens that maximizes visual Strehl ratio. Results Despite changes in ocular aberrations and pupil size during binocular viewing, retinal image quality and visual acuity typically remain high for all target vergences. When accommodative errors lead to sub-optimal retinal image quality, acuity and measured image quality both decline. However, the effect of accommodation errors of on visual acuity are mitigated by pupillary constriction associated with accommodation and binocular convergence and also to binocular summation of dissimilar retinal image blur. Under monocular viewing conditions some subjects displayed significant accommodative lag that reduced visual performance, an effect that was exacerbated by pharmacological dilation of the pupil. Conclusions Spurious measurement of accommodative error can be avoided when the image quality metric used to determine refractive state is compatible with the focusing criteria used by the visual system to control accommodation. Real focusing errors of the accommodating eye do not necessarily produce a reliably measurable loss of image quality or clinically significant loss of visual performance, probably because of increased depth-of-focus due to pupil constriction. When retinal image quality is close to maximum achievable (given the eye’s higher-order aberrations), acuity is also near maximum. A combination of accommodative lag, reduced image quality, and reduced

  16. MIQM: a multicamera image quality measure.

    PubMed

    Solh, Mashhour; AlRegib, Ghassan

    2012-09-01

    Although several subjective and objective quality assessment methods have been proposed in the literature for images and videos from single cameras, no comparable effort has been devoted to the quality assessment of multicamera images. With the increasing popularity of multiview applications, quality assessment of multicamera images and videos is becoming fundamental to the development of these applications. Image quality is affected by several factors, such as camera configuration, number of cameras, and the calibration process. In order to develop an objective metric specifically designed for multicamera systems, we identified and quantified two types of visual distortions in multicamera images: photometric distortions and geometric distortions. The relative distortion between individual camera scenes is a major factor in determining the overall perceived quality. In this paper, we show that such distortions can be translated into luminance, contrast, spatial motion, and edge-based structure components. We propose three different indices that can quantify these components. We provide examples to demonstrate the correlation among these components and the corresponding indices. Then, we combine these indices into one multicamera image quality measure (MIQM). Results and comparisons with other measures, such as peak signal-to noise ratio, mean structural similarity, and visual information fidelity show that MIQM outperforms other measures in capturing the perceptual fidelity of multicamera images. Finally, we verify the results against subjective evaluation. PMID:22645264

  17. Quality assessment for hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Chen, Yuheng; Chen, Xinhua; Zhou, Jiankang; Shen, Weimin

    2014-11-01

    Image quality assessment is an essential value judgement approach for many applications. Multi & hyper spectral imaging has more judging essentials than grey scale or RGB imaging and its image quality assessment job has to cover up all-around evaluating factors. This paper presents an integrating spectral imaging quality assessment project, in which spectral-based, radiometric-based and spatial-based statistical behavior for three hyperspectral imagers are jointly executed. Spectral response function is worked out based on discrete illumination images and its spectral performance is deduced according to its FWHM and spectral excursion value. Radiometric response ability of different spectral channel under both on-ground and airborne imaging condition is judged by SNR computing based upon local RMS extraction and statistics method. Spatial response evaluation of the spectral imaging instrument is worked out by MTF computing with slanted edge analysis method. Reported pioneering systemic work in hyperspectral imaging quality assessment is carried out with the help of several domestic dominating work units, which not only has significance in the development of on-ground and in-orbit instrument performance evaluation technique but also takes on reference value for index demonstration and design optimization for instrument development.

  18. Factors Affecting the Quality of Staff Development.

    ERIC Educational Resources Information Center

    Purcell, Larry O.

    A review of the literature concerning the effectiveness and quality of staff development programs focuses on factors that affect the success of such programs. These factors include: individual concerns, training activities, applications, qualifications of consultants, scheduling, strategies, facilities, feedback, collaboration, and outcomes. It is…

  19. Affect, Meaning and Quality of Life

    ERIC Educational Resources Information Center

    Hughes, Michael

    2006-01-01

    Research on quality of life in sociology is largely focused on a narrow range of dimensions including affect, happiness and satisfaction. It largely avoids a concern with the meanings that provide people with the purpose, significance, validity and coherence that are a basis of social relationships and social integration. Evidence is presented…

  20. Watermelon quality traits as affected by ploidy

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Growers offering high quality watermelons [Citrullus lanatus (Thumb.), Matsum & Nakai] that are also high in phytonutrients will have stronger market opportunities. In order to offer highly nutritious fruit, the industry must understand the nature of phytonutrient accumulation as it is affected by ...

  1. Nonmotion factors which can affect ride quality

    NASA Technical Reports Server (NTRS)

    Conner, D. W.

    1975-01-01

    Data pertaining to nonmotion factors affecting ride quality of transport aircraft were obtained as part of NASA in-house and sponsored research studies carried out onboard commuter-airline and research aircraft. From these data, quantitative effects on passenger discomfort of seat width, seat legroom, change in cabin pressure, and cabin noise are presented. Visual cue effects are also discussed.

  2. Foveated wavelet image quality index

    NASA Astrophysics Data System (ADS)

    Wang, Zhou; Bovik, Alan C.; Lu, Ligang; Kouloheris, Jack L.

    2001-12-01

    The human visual system (HVS) is highly non-uniform in sampling, coding, processing and understanding. The spatial resolution of the HVS is highest around the point of fixation (foveation point) and decreases rapidly with increasing eccentricity. Currently, most image quality measurement methods are designed for uniform resolution images. These methods do not correlate well with the perceived foveated image quality. Wavelet analysis delivers a convenient way to simultaneously examine localized spatial as well as frequency information. We developed a new image quality metric called foveated wavelet image quality index (FWQI) in the wavelet transform domain. FWQI considers multiple factors of the HVS, including the spatial variance of the contrast sensitivity function, the spatial variance of the local visual cut-off frequency, the variance of human visual sensitivity in different wavelet subbands, and the influence of the viewing distance on the display resolution and the HVS features. FWQI can be employed for foveated region of interest (ROI) image coding and quality enhancement. We show its effectiveness by using it as a guide for optimal bit assignment of an embedded foveated image coding system. The coding system demonstrates very good coding performance and scalability in terms of foveated objective as well as subjective quality measurement.

  3. Factors affecting water quality in Cherokee Reservoir

    SciTech Connect

    Iwanski, M.L.; Higgins, J.M.; Kim, B.R.; Young, R.C.

    1980-07-01

    The purpose was to: (1) define reservoir problems related to water quality conditions; (2) identify the probable causes of these problems; and (3) recommend procedures for achieving needed reservoir water quality improvements. This report presents the project findings to date and suggests steps for upgrading the quality of Cherokee Reservoir. Section II presents background information on the characteristics of the basin, the reservoir, and the beneficial uses of the reservoir. Section III identifies the impacts of existing reservoir water quality on uses of the reservoir for water supply, fishery resources, recreation, and waste assimilation. Section IV presents an assessment of cause-effect relationships. The factors affecting water quality addressed in Section IV are: (1) reservoir thermal stratification and hydrodynamics; (2) dissolved oxygen depletion; (3) eutrophication; (4) toxic substances; and (5) reservoir fisheries. Section V presents a preliminary evaluation of alternatives for improving the quality of Cherokee Reservoir. Section VI presents preliminary conclusions and recommendations for developing and implementing a reservoir water quality management plan. 7 references, 22 figures, 21 tables.

  4. Color image processing for date quality evaluation

    NASA Astrophysics Data System (ADS)

    Lee, Dah Jye; Archibald, James K.

    2010-01-01

    Many agricultural non-contact visual inspection applications use color image processing techniques because color is often a good indicator of product quality. Color evaluation is an essential step in the processing and inventory control of fruits and vegetables that directly affects profitability. Most color spaces such as RGB and HSV represent colors with three-dimensional data, which makes using color image processing a challenging task. Since most agricultural applications only require analysis on a predefined set or range of colors, mapping these relevant colors to a small number of indexes allows simple and efficient color image processing for quality evaluation. This paper presents a simple but efficient color mapping and image processing technique that is designed specifically for real-time quality evaluation of Medjool dates. In contrast with more complex color image processing techniques, the proposed color mapping method makes it easy for a human operator to specify and adjust color-preference settings for different color groups representing distinct quality levels. Using this color mapping technique, the color image is first converted to a color map that has one color index represents a color value for each pixel. Fruit maturity level is evaluated based on these color indices. A skin lamination threshold is then determined based on the fruit surface characteristics. This adaptive threshold is used to detect delaminated fruit skin and hence determine the fruit quality. The performance of this robust color grading technique has been used for real-time Medjool date grading.

  5. Can Supersaturation Affect Protein Crystal Quality?

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar

    2013-01-01

    In quiescent environments (microgravity, capillary tubes, gels) formation of a depletion zone is to be expected, due either to limited sedimentation, density driven convection or a combination of both. The formation of a depletion zone can: Modify solution supersaturation near crystal; Give rise to impurity partitioning. It is conjectured that both supersaturation and impurity partitioning affect protein crystal quality and size. Further detailed investigations on various proteins are needed to assess above hypothesis.

  6. Video and image quality

    NASA Astrophysics Data System (ADS)

    Aldridge, Jim

    1995-09-01

    This paper presents some of the results of a UK government research program into methods of improving the effectiveness of CCTV surveillance systems. The paper identifies the major components of video security systems and primary causes of unsatisfactory images. A method is outline for relating the picture detail limitations imposed by each system component on overall system performance. The paper also points out some possible difficulties arising from the use of emerging new technology.

  7. Can Solution Supersaturation Affect Protein Crystal Quality?

    NASA Technical Reports Server (NTRS)

    Gorti, Sridhar

    2013-01-01

    The formation of large protein crystals of "high quality" is considered a characteristic manifestation of microgravity. The physical processes that predict the formation of large, high quality protein crystals in the microgravity environment of space are considered rooted in the existence of a "depletion zone" in the vicinity of crystal. Namely, it is considered reasonable that crystal quality suffers in earth-grown crystals as a result of the incorporation of large aggregates, micro-crystals and/or large molecular weight "impurities", processes which are aided by density driven convective flow or mixing at the crystal-liquid interface. Sedimentation and density driven convection produce unfavorable solution conditions in the vicinity of the crystal surface, which promotes rapid crystal growth to the detriment of crystal size and quality. In this effort, we shall further present the hypothesis that the solution supersaturatoin at the crystal surface determines the growth mechanism, or mode, by which protein crystals grow. It is further hypothesized that protein crystal quality is affected by the mechanism or mode of crystal growth. Hence the formation of a depletion zone in microgravity environment is beneficial due to inhibition of impurity incorporatoin as well as preventing a kinetic roughening transition. It should be noted that for many proteins the magnitude of neither protein crystal growth rates nor solution supersaturation are predictors of a kinetic roughening transition. That is, the kinetic roughening transition supersaturation must be dtermined for each individual protein.

  8. Lessions learned in WISE image quality

    NASA Astrophysics Data System (ADS)

    Kendall, Martha; Duval, Valerie G.; Larsen, Mark F.; Heinrichsen, Ingolf H.; Esplin, Roy W.; Shannon, Mark; Wright, Edward L.

    2010-08-01

    The Wide-Field Infrared Survey Explorer (WISE) mission launched in December of 2009 is a true success story. The mission is performing beyond expectations on-orbit and maintained cost and schedule throughout. How does such a thing happen? A team constantly focused on mission success is a key factor. Mission success is more than a program meeting its ultimate science goals; it is also meeting schedule and cost goals to avoid cancellation. The WISE program can attribute some of its success in achieving the image quality needed to meet science goals to lessons learned along the way. A requirement was missed in early decomposition, the absence of which would have adversely affected end-to-end system image quality. Fortunately, the ability of the cross-organizational team to focus on fixing the problem without pointing fingers or waiting for paperwork was crucial in achieving a timely solution. Asking layman questions early in the program could have revealed requirement flowdown misunderstandings between spacecraft control stability and image processing needs. Such is the lesson learned with the WISE spacecraft Attitude Determination & Control Subsystem (ADCS) jitter control and the image data reductions needs. Spacecraft motion can affect image quality in numerous ways. Something as seemingly benign as different terminology being used by teammates in separate groups working on data reduction, spacecraft ADCS, the instrument, mission operations, and the science proved to be a risk to system image quality. While the spacecraft was meeting the allocated jitter requirement , the drift rate variation need was not being met. This missing need was noticed about a year before launch and with a dedicated team effort, an adjustment was made to the spacecraft ADCS control. WISE is meeting all image quality requirements on-orbit thanks to a diligent team noticing something was missing before it was too late and applying their best effort to find a solution.

  9. Fovea based image quality assessment

    NASA Astrophysics Data System (ADS)

    Guo, Anan; Zhao, Debin; Liu, Shaohui; Cao, Guangyao

    2010-07-01

    Humans are the ultimate receivers of the visual information contained in an image, so the reasonable method of image quality assessment (IQA) should follow the properties of the human visual system (HVS). In recent years, IQA methods based on HVS-models are slowly replacing classical schemes, such as mean squared error (MSE) and Peak Signal-to-Noise Ratio (PSNR). IQA-structural similarity (SSIM) regarded as one of the most popular HVS-based methods of full reference IQA has apparent improvements in performance compared with traditional metrics in nature, however, it performs not very well when the images' structure is destroyed seriously or masked by noise. In this paper, a new efficient fovea based structure similarity image quality assessment (FSSIM) is proposed. It enlarges the distortions in the concerned positions adaptively and changes the importances of the three components in SSIM. FSSIM predicts the quality of an image through three steps. First, it computes the luminance, contrast and structure comparison terms; second, it computes the saliency map by extracting the fovea information from the reference image with the features of HVS; third, it pools the above three terms according to the processed saliency map. Finally, a commonly experimental database LIVE IQA is used for evaluating the performance of the FSSIM. Experimental results indicate that the consistency and relevance between FSSIM and mean opinion score (MOS) are both better than SSIM and PSNR clearly.

  10. Landsat image data quality studies

    NASA Technical Reports Server (NTRS)

    Schueler, C. F.; Salomonson, V. V.

    1985-01-01

    Preliminary results of the Landsat-4 Image Data Quality Analysis (LIDQA) program to characterize the data obtained using the Thematic Mapper (TM) instrument on board the Landsat-4 and Landsat-5 satellites are reported. TM design specifications were compared to the obtained data with respect to four criteria, including spatial resolution; geometric fidelity; information content; and image relativity to Multispectral Scanner (MSS) data. The overall performance of the TM was rated excellent despite minor instabilities and radiometric anomalies in the data. Spatial performance of the TM exceeded design specifications in terms of both image sharpness and geometric accuracy, and the image utility of the TM data was at least twice as high as MSS data. The separability of alfalfa and sugar beet fields in a TM image is demonstrated.

  11. Measuring image quality in overlapping areas of panoramic composed images

    NASA Astrophysics Data System (ADS)

    Mitjà, Carles; Bover, Toni; Escofet, Jaume

    2012-06-01

    Several professional photographic applications uses the merging of consecutive overlapping images in order to obtain bigger files by means of stitching techniques or extended field of view (FOV) for panoramic images. All of those applications share the fact that the final composed image is obtained by overlapping the neighboring areas of consecutive individual images taken as a mosaic or a series of tiles over the scene, from the same point of view. Any individual image taken with a given lens can carry residual aberrations and several of them will affect more probably the borders of the image frame. Furthermore, the amount of distortion aberration present in the images of a given lens will be reversed in position for the two overlapping areas of a pair of consecutive takings. Finally, the different images used in composing the final one have corresponding overlapping areas taken with different perspective. From all the previously stated can be derived that the software employed must remap all the pixel information in order to resize and match image features in those overlapping areas, providing a final composed image with the desired perspective projection. The work presented analyse two panoramic format images taken with a pair of lenses and composed by means of a state of the art stitching software. Then, a series of images are taken to cover an FOV three times the original lens FOV, the images are merged by means of a software of common use in professional panoramic photography and the final image quality is evaluated through a series of targets positioned in strategic locations over the whole taking field of view. That allows measuring the resulting Resolution and Modulation Transfer Function (MTF). The results are shown compared with the previous measures on the original individual images.

  12. FFDM image quality assessment using computerized image texture analysis

    NASA Astrophysics Data System (ADS)

    Berger, Rachelle; Carton, Ann-Katherine; Maidment, Andrew D. A.; Kontos, Despina

    2010-04-01

    Quantitative measures of image quality (IQ) are routinely obtained during the evaluation of imaging systems. These measures, however, do not necessarily correlate with the IQ of the actual clinical images, which can also be affected by factors such as patient positioning. No quantitative method currently exists to evaluate clinical IQ. Therefore, we investigated the potential of using computerized image texture analysis to quantitatively assess IQ. Our hypothesis is that image texture features can be used to assess IQ as a measure of the image signal-to-noise ratio (SNR). To test feasibility, the "Rachel" anthropomorphic breast phantom (Model 169, Gammex RMI) was imaged with a Senographe 2000D FFDM system (GE Healthcare) using 220 unique exposure settings (target/filter, kVs, and mAs combinations). The mAs were varied from 10%-300% of that required for an average glandular dose (AGD) of 1.8 mGy. A 2.5cm2 retroareolar region of interest (ROI) was segmented from each image. The SNR was computed from the ROIs segmented from images linear with dose (i.e., raw images) after flat-field and off-set correction. Image texture features of skewness, coarseness, contrast, energy, homogeneity, and fractal dimension were computed from the Premium ViewTM postprocessed image ROIs. Multiple linear regression demonstrated a strong association between the computed image texture features and SNR (R2=0.92, p<=0.001). When including kV, target and filter as additional predictor variables, a stronger association with SNR was observed (R2=0.95, p<=0.001). The strong associations indicate that computerized image texture analysis can be used to measure image SNR and potentially aid in automating IQ assessment as a component of the clinical workflow. Further work is underway to validate our findings in larger clinical datasets.

  13. Quality metrics for sensor images

    NASA Technical Reports Server (NTRS)

    Ahumada, AL

    1993-01-01

    Methods are needed for evaluating the quality of augmented visual displays (AVID). Computational quality metrics will help summarize, interpolate, and extrapolate the results of human performance tests with displays. The FLM Vision group at NASA Ames has been developing computational models of visual processing and using them to develop computational metrics for similar problems. For example, display modeling systems use metrics for comparing proposed displays, halftoning optimizing methods use metrics to evaluate the difference between the halftone and the original, and image compression methods minimize the predicted visibility of compression artifacts. The visual discrimination models take as input two arbitrary images A and B and compute an estimate of the probability that a human observer will report that A is different from B. If A is an image that one desires to display and B is the actual displayed image, such an estimate can be regarded as an image quality metric reflecting how well B approximates A. There are additional complexities associated with the problem of evaluating the quality of radar and IR enhanced displays for AVID tasks. One important problem is the question of whether intruding obstacles are detectable in such displays. Although the discrimination model can handle detection situations by making B the original image A plus the intrusion, this detection model makes the inappropriate assumption that the observer knows where the intrusion will be. Effects of signal uncertainty need to be added to our models. A pilot needs to make decisions rapidly. The models need to predict not just the probability of a correct decision, but the probability of a correct decision by the time the decision needs to be made. That is, the models need to predict latency as well as accuracy. Luce and Green have generated models for auditory detection latencies. Similar models are needed for visual detection. Most image quality models are designed for static imagery

  14. [Factors that affect inpatients' quality of sleep].

    PubMed

    da Costa, Shíntia Viana; Ceolim, Maria Filomena

    2013-02-01

    The aim of this study was to identify factors that interfere with the sleep quality of patients admitted to a university hospital in a city in the state of São Paulo, Brazil. This was an exploratory, cross sectional study using non-probability sampling. Participants were 117 patients (59% men, mean age 48.0 years, standard deviation 16.9) hospitalized for at least 72 hours in stable clinical condition. The data were collected with an identification questionnaire and the Factors Affecting Sleep Quality (FASQ) questionnaire. Data processing was performed with descriptive statistics; each item of the FASQ underwent a test and a retest. The factors most often reported were waking up early (55.6%), disrupted sleep (52.1%), excessive lighting (34.2%), receipt of care by nursing staff (33.3%) and organic disorders such as pain and fatigue (26.5%). It is suggested that nurses should plan interventions to modify factors that require intense noise and lighting at night in order to reduce disruption and, consequently, sleep deprivation among patients. PMID:23515802

  15. Quality assessment for spectral domain optical coherence tomography (OCT) images

    NASA Astrophysics Data System (ADS)

    Liu, Shuang; Paranjape, Amit S.; Elmaanaoui, Badr; Dewelle, Jordan; Rylander, H. Grady, III; Markey, Mia K.; Milner, Thomas E.

    2009-02-01

    Retinal nerve fiber layer (RNFL) thickness, a measure of glaucoma progression, can be measured in images acquired by spectral domain optical coherence tomography (OCT). The accuracy of RNFL thickness estimation, however, is affected by the quality of the OCT images. In this paper, a new parameter, signal deviation (SD), which is based on the standard deviation of the intensities in OCT images, is introduced for objective assessment of OCT image quality. Two other objective assessment parameters, signal to noise ratio (SNR) and signal strength (SS), are also calculated for each OCT image. The results of the objective assessment are compared with subjective assessment. In the subjective assessment, one OCT expert graded the image quality according to a three-level scale (good, fair, and poor). The OCT B-scan images of the retina from six subjects are evaluated by both objective and subjective assessment. From the comparison, we demonstrate that the objective assessment successfully differentiates between the acceptable quality images (good and fair images) and poor quality OCT images as graded by OCT experts. We evaluate the performance of the objective assessment under different quality assessment parameters and demonstrate that SD is the best at distinguishing between fair and good quality images. The accuracy of RNFL thickness estimation is improved significantly after poor quality OCT images are rejected by automated objective assessment using the SD, SNR, and SS.

  16. Undernutrition affects embryo quality of superovulated ewes.

    PubMed

    Abecia, J A; Forcada, F; Palacín, I; Sánchez-Prieto, L; Sosa, C; Fernández-Foren, A; Meikle, A

    2015-02-01

    To determine the effect of undernutrition on embryo production and quality in superovulated sheep, 45 ewes were allocated into two groups to be fed diets that provided 1.5 (control, C; n = 20) or 0.5 (low nutrition, L; n = 25) times daily requirements for maintenance, from oestrous synchronization with intravaginal sponges to embryo collection. Embryos were collected 7 days after the onset of oestrus (day 0). Low nutrition resulted in lower live weight and body condition at embryo collection (P < 0.05). Diet (P < 0.01) and day of sampling (P < 0.001) significantly affected plasma non-esterified fatty acid (NEFA) and insulin concentrations. Plasma leptin concentrations decreased on day 7 only in L ewes. A significant effect of dietary treatment (P < 0.05) and day (P < 0.0001) was observed on plasma insulin-like growth factor (IGF)-I concentrations. The number of recovered oocytes and embryos did not differ between the groups (L: 15.4 ± 0.4; C: 12.4 ± 0.4). Recovery rate was lower (P < 0.05) in the L (60%) than in the C group (73%). The total number of embryos and number of viable-transferable embryos (5.0 ± 0.3 and 3.4 ± 0.3 embryos, respectively) of the L group were lower (P < 0.1) when compared with controls (8.4 ± 0.4 and 6.2 ± 0.4 embryos, respectively). Undernutrition during the period of superovulation and early embryonic development reduced total and viable number of embryos. These effects might be mediated by disruption of endocrine homeostasis, oviduct environment and/or oocyte quality. PMID:24103562

  17. Using short-wave infrared imaging for fruit quality evaluation

    NASA Astrophysics Data System (ADS)

    Zhang, Dong; Lee, Dah-Jye; Desai, Alok

    2013-12-01

    Quality evaluation of agricultural and food products is important for processing, inventory control, and marketing. Fruit size and surface quality are two important quality factors for high-quality fruit such as Medjool dates. Fruit size is usually measured by length that can be done easily by simple image processing techniques. Surface quality evaluation on the other hand requires more complicated design, both in image acquisition and image processing. Skin delamination is considered a major factor that affects fruit quality and its value. This paper presents an efficient histogram analysis and image processing technique that is designed specifically for real-time surface quality evaluation of Medjool dates. This approach, based on short-wave infrared imaging, provides excellent image contrast between the fruit surface and delaminated skin, which allows significant simplification of image processing algorithm and reduction of computational power requirements. The proposed quality grading method requires very simple training procedure to obtain a gray scale image histogram for each quality level. Using histogram comparison, each date is assigned to one of the four quality levels and an optimal threshold is calculated for segmenting skin delamination areas from the fruit surface. The percentage of the fruit surface that has skin delamination can then be calculated for quality evaluation. This method has been implemented and used for commercial production and proven to be efficient and accurate.

  18. Study on the improvement of overall optical image quality via digital image processing

    NASA Astrophysics Data System (ADS)

    Tsai, Cheng-Mu; Fang, Yi Chin; Lin, Yu Chin

    2008-12-01

    This paper studies the effects of improving overall optical image quality via Digital Image Processing (DIP) and compares the promoted optical image with the non-processed optical image. Seen from the optical system, the improvement of image quality has a great influence on chromatic aberration and monochromatic aberration. However, overall image capture systems-such as cellphones and digital cameras-include not only the basic optical system but also many other factors, such as the electronic circuit system, transducer system, and so forth, whose quality can directly affect the image quality of the whole picture. Therefore, in this thesis Digital Image Processing technology is utilized to improve the overall image. It is shown via experiments that system modulation transfer function (MTF) based on the proposed DIP technology and applied to a comparatively bad optical system can be comparable to, even possibly superior to, the system MTF derived from a good optical system.

  19. Image quality assessment in the low quality regime

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2012-03-01

    Traditionally, image quality estimators have been designed and optimized to operate over the entire quality range of images in a database, from very low quality to visually lossless. However, if quality estimation is limited to a smaller quality range, their performances drop dramatically, and many image applications only operate over such a smaller range. This paper is concerned with one such range, the low-quality regime, which is defined as the interval of perceived quality scores where there exists a linear relationship between the perceived quality scores and the perceived utility scores and exists at the low-quality end of image databases. Using this definition, this paper describes a subjective experiment to determine the low-quality regime for databases of distorted images that include perceived quality scores but not perceived utility scores, such as CSIQ and LIVE. The performances of several image utility and quality estimators are evaluated in the low-quality regime, indicating that utility estimators can be successfully applied to estimate perceived quality in this regime. Omission of the lowestfrequency image content is shown to be crucial to the performances of both kinds of estimators. Additionally, this paper establishes an upper-bound for the performances of quality estimators in the LQR, using a family of quality estimators based on VIF. The resulting optimal quality estimator indicates that estimating quality in the low-quality regime is robust to exact frequency pooling weights, and that near-optimal performance can be achieved by a variety of estimators providing that they substantially emphasize the appropriate frequency content.

  20. Assessing product image quality for online shopping

    NASA Astrophysics Data System (ADS)

    Goswami, Anjan; Chung, Sung H.; Chittar, Naren; Islam, Atiq

    2012-01-01

    Assessing product-image quality is important in the context of online shopping. A high quality image that conveys more information about a product can boost the buyer's confidence and can get more attention. However, the notion of image quality for product-images is not the same as that in other domains. The perception of quality of product-images depends not only on various photographic quality features but also on various high level features such as clarity of the foreground or goodness of the background etc. In this paper, we define a notion of product-image quality based on various such features. We conduct a crowd-sourced experiment to collect user judgments on thousands of eBay's images. We formulate a multi-class classification problem for modeling image quality by classifying images into good, fair and poor quality based on the guided perceptual notions from the judges. We also conduct experiments with regression using average crowd-sourced human judgments as target. We compute a pseudo-regression score with expected average of predicted classes and also compute a score from the regression technique. We design many experiments with various sampling and voting schemes with crowd-sourced data and construct various experimental image quality models. Most of our models have reasonable accuracies (greater or equal to 70%) on test data set. We observe that our computed image quality score has a high (0.66) rank correlation with average votes from the crowd sourced human judgments.

  1. Infrared image quality evaluation method without reference image

    NASA Astrophysics Data System (ADS)

    Yue, Song; Ren, Tingting; Wang, Chengsheng; Lei, Bo; Zhang, Zhijie

    2013-09-01

    Since infrared image quality depends on many factors such as optical performance and electrical noise of thermal imager, image quality evaluation becomes an important issue which can conduce to both image processing afterward and capability improving of thermal imager. There are two ways of infrared image quality evaluation, with or without reference image. For real-time thermal image, the method without reference image is preferred because it is difficult to get a standard image. Although there are various kinds of methods for evaluation, there is no general metric for image quality evaluation. This paper introduces a novel method to evaluate infrared image without reference image from five aspects: noise, clarity, information volume and levels, information in frequency domain and the capability of automatic target recognition. Generally, the basic image quality is obtained from the first four aspects, and the quality of target is acquired from the last aspect. The proposed method is tested on several infrared images captured by different thermal imagers. Calculate the indicators and compare with human vision results. The evaluation shows that this method successfully describes the characteristics of infrared image and the result is consistent with human vision system.

  2. The study of surgical image quality evaluation system by subjective quality factor method

    NASA Astrophysics Data System (ADS)

    Zhang, Jian J.; Xuan, Jason R.; Yang, Xirong; Yu, Honggang; Koullick, Edouard

    2016-03-01

    GreenLightTM procedure is an effective and economical way of treatment of benign prostate hyperplasia (BPH); there are almost a million of patients treated with GreenLightTM worldwide. During the surgical procedure, the surgeon or physician will rely on the monitoring video system to survey and confirm the surgical progress. There are a few obstructions that could greatly affect the image quality of the monitoring video, like laser glare by the tissue and body fluid, air bubbles and debris generated by tissue evaporation, and bleeding, just to name a few. In order to improve the physician's visual experience of a laser surgical procedure, the system performance parameter related to image quality needs to be well defined. However, since image quality is the integrated set of perceptions of the overall degree of excellence of an image, or in other words, image quality is the perceptually weighted combination of significant attributes (contrast, graininess …) of an image when considered in its marketplace or application, there is no standard definition on overall image or video quality especially for the no-reference case (without a standard chart as reference). In this study, Subjective Quality Factor (SQF) and acutance are used for no-reference image quality evaluation. Basic image quality parameters, like sharpness, color accuracy, size of obstruction and transmission of obstruction, are used as subparameter to define the rating scale for image quality evaluation or comparison. Sample image groups were evaluated by human observers according to the rating scale. Surveys of physician groups were also conducted with lab generated sample videos. The study shows that human subjective perception is a trustworthy way of image quality evaluation. More systematic investigation on the relationship between video quality and image quality of each frame will be conducted as a future study.

  3. Automated FMV image quality assessment based on power spectrum statistics

    NASA Astrophysics Data System (ADS)

    Kalukin, Andrew

    2015-05-01

    Factors that degrade image quality in video and other sensor collections, such as noise, blurring, and poor resolution, also affect the spatial power spectrum of imagery. Prior research in human vision and image science from the last few decades has shown that the image power spectrum can be useful for assessing the quality of static images. The research in this article explores the possibility of using the image power spectrum to automatically evaluate full-motion video (FMV) imagery frame by frame. This procedure makes it possible to identify anomalous images and scene changes, and to keep track of gradual changes in quality as collection progresses. This article will describe a method to apply power spectral image quality metrics for images subjected to simulated blurring, blocking, and noise. As a preliminary test on videos from multiple sources, image quality measurements for image frames from 185 videos are compared to analyst ratings based on ground sampling distance. The goal of the research is to develop an automated system for tracking image quality during real-time collection, and to assign ratings to video clips for long-term storage, calibrated to standards such as the National Imagery Interpretability Rating System (NIIRS).

  4. An Underwater Color Image Quality Evaluation Metric.

    PubMed

    Yang, Miao; Sowmya, Arcot

    2015-12-01

    Quality evaluation of underwater images is a key goal of underwater video image retrieval and intelligent processing. To date, no metric has been proposed for underwater color image quality evaluation (UCIQE). The special absorption and scattering characteristics of the water medium do not allow direct application of natural color image quality metrics especially to different underwater environments. In this paper, subjective testing for underwater image quality has been organized. The statistical distribution of the underwater image pixels in the CIELab color space related to subjective evaluation indicates the sharpness and colorful factors correlate well with subjective image quality perception. Based on these, a new UCIQE metric, which is a linear combination of chroma, saturation, and contrast, is proposed to quantify the non-uniform color cast, blurring, and low-contrast that characterize underwater engineering and monitoring images. Experiments are conducted to illustrate the performance of the proposed UCIQE metric and its capability to measure the underwater image enhancement results. They show that the proposed metric has comparable performance to the leading natural color image quality metrics and the underwater grayscale image quality metrics available in the literature, and can predict with higher accuracy the relative amount of degradation with similar image content in underwater environments. Importantly, UCIQE is a simple and fast solution for real-time underwater video processing. The effectiveness of the presented measure is also demonstrated by subjective evaluation. The results show better correlation between the UCIQE and the subjective mean opinion score. PMID:26513783

  5. Improving the Quality of Imaging in the Emergency Department.

    PubMed

    Blackmore, C Craig; Castro, Alexandra

    2015-12-01

    Imaging is critical for the care of emergency department (ED) patients. However, much of the imaging performed for acute care today is overutilization, creating substantial cost without significant benefit. Further, the value of imaging is not easily defined, as imaging only affects outcomes indirectly, through interaction with treatment. Improving the quality, including appropriateness, of emergency imaging requires understanding of how imaging contributes to patient care. The six-tier efficacy hierarchy of Fryback and Thornbury enables understanding of the value of imaging on multiple levels, ranging from technical efficacy to medical decision-making and higher-level patient and societal outcomes. The imaging efficacy hierarchy also allows definition of imaging quality through the Institute of Medicine (IOM)'s quality domains of safety, effectiveness, patient-centeredness, timeliness, efficiency, and equitability and provides a foundation for quality improvement. In this article, the authors elucidate the Fryback and Thornbury framework to define the value of imaging in the ED and to relate emergency imaging to the IOM quality domains. PMID:26568040

  6. Process perspective on image quality evaluation

    NASA Astrophysics Data System (ADS)

    Leisti, Tuomas; Halonen, Raisa; Kokkonen, Anna; Weckman, Hanna; Mettänen, Marja; Lensu, Lasse; Ritala, Risto; Oittinen, Pirkko; Nyman, Göte

    2008-01-01

    The psychological complexity of multivariate image quality evaluation makes it difficult to develop general image quality metrics. Quality evaluation includes several mental processes and ignoring these processes and the use of a few test images can lead to biased results. By using a qualitative/quantitative (Interpretation Based Quality, IBQ) methodology, we examined the process of pair-wise comparison in a setting, where the quality of the images printed by laser printer on different paper grades was evaluated. Test image consisted of a picture of a table covered with several objects. Three other images were also used, photographs of a woman, cityscape and countryside. In addition to the pair-wise comparisons, observers (N=10) were interviewed about the subjective quality attributes they used in making their quality decisions. An examination of the individual pair-wise comparisons revealed serious inconsistencies in observers' evaluations on the test image content, but not on other contexts. The qualitative analysis showed that this inconsistency was due to the observers' focus of attention. The lack of easily recognizable context in the test image may have contributed to this inconsistency. To obtain reliable knowledge of the effect of image context or attention on subjective image quality, a qualitative methodology is needed.

  7. Factors Affecting School Quality in Florida

    ERIC Educational Resources Information Center

    Thornton, Barry; Arbogast, Gordon

    2014-01-01

    This paper examines the factors that are theorized to be determinants of school quality in the 67 counties of Florida from 2000 to 2011. The model constructed for this purpose is comprised of a mix of independent variables that include county educational attainment (number of high school graduates and State University System enrollees) and…

  8. Automatic no-reference image quality assessment.

    PubMed

    Li, Hongjun; Hu, Wei; Xu, Zi-Neng

    2016-01-01

    No-reference image quality assessment aims to predict the visual quality of distorted images without examining the original image as a reference. Most no-reference image quality metrics which have been already proposed are designed for one or a set of predefined specific distortion types and are unlikely to generalize for evaluating images degraded with other types of distortion. There is a strong need of no-reference image quality assessment methods which are applicable to various distortions. In this paper, the authors proposed a no-reference image quality assessment method based on a natural image statistic model in the wavelet transform domain. A generalized Gaussian density model is employed to summarize the marginal distribution of wavelet coefficients of the test images, so that correlative parameters are needed for the evaluation of image quality. The proposed algorithm is tested on three large-scale benchmark databases. Experimental results demonstrate that the proposed algorithm is easy to implement and computational efficient. Furthermore, our method can be applied to many well-known types of image distortions, and achieves a good quality of prediction performance. PMID:27468398

  9. Phase congruency assesses hyperspectral image quality

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Zhong, Cheng

    2012-10-01

    Blind image quality assessment (QA) is a tough task especially for hyperspectral imagery which is degraded by noise, distortion, defocus, and other complex factors. Subjective hyperspectral imagery QA methods are basically measured the degradation of image from human perceptual visual quality. As the most important image quality measurement features, noise and blur, determined the image quality greatly, are employed to predict the objective hyperspectral imagery quality of each band. We demonstrate a novel no-reference hyperspectral imagery QA model based on phase congruency (PC), which is a dimensionless quantity and provides an absolute measure of the significance of feature point. First, Log Gabor wavelet is used to calculate the phase congruency of frequencies of each band image. The relationship between noise and PC can be derived from above transformation under the assumption that noise is additive. Second, PC focus measure evaluation model is proposed to evaluate blur caused by different amounts of defocus. The ratio and mean factors of edge blur level and noise is defined to assess the quality of each band image. This image QA method obtains excellent correlation with subjective image quality score without any reference. Finally, the PC information is utilized to improve the quality of some bands images.

  10. Impact of image acquisition timing on image quality for dual energy contrast-enhanced breast tomosynthesis

    NASA Astrophysics Data System (ADS)

    Hill, Melissa L.; Mainprize, James G.; Puong, Sylvie; Carton, Ann-Katherine; Iordache, Razvan; Muller, Serge; Yaffe, Martin J.

    2012-03-01

    Dual-energy contrast-enhanced digital breast tomosynthesis (DE CE-DBT) image quality is affected by a large parameter space including the tomosynthesis acquisition geometry, imaging technique factors, the choice of reconstruction algorithm, and the subject breast characteristics. The influence of most of these factors on reconstructed image quality is well understood for DBT. However, due to the contrast agent uptake kinetics in CE imaging, the subject breast characteristics change over time, presenting a challenge for optimization . In this work we experimentally evaluate the sensitivity of the reconstructed image quality to timing of the low-energy and high-energy images and changes in iodine concentration during image acquisition. For four contrast uptake patterns, a variety of acquisition protocols were tested with different timing and geometry. The influence of the choice of reconstruction algorithm (SART or FBP) was also assessed. Image quality was evaluated in terms of the lesion signal-difference-to-noise ratio (LSDNR) in the central slice of DE CE-DBT reconstructions. Results suggest that for maximum image quality, the low- and high-energy image acquisitions should be made within one x-ray tube sweep, as separate low- and high-energy tube sweeps can degrade LSDNR. In terms of LSDNR per square-root dose, the image quality is nearly equal between SART reconstructions with 9 and 15 angular views, but using fewer angular views can result in a significant improvement in the quantitative accuracy of the reconstructions due to the shorter imaging time interval.

  11. Mind Wandering, Sleep Quality, Affect and Chronotype: An Exploratory Study

    PubMed Central

    Carciofo, Richard; Du, Feng; Song, Nan; Zhang, Kan

    2014-01-01

    Poor sleep quality impairs cognition, including executive functions and concentration, but there has been little direct research on the relationships between sleep quality and mind wandering or daydreaming. Evening chronotype is associated with poor sleep quality, more mind wandering and more daydreaming; negative affect is also a mutual correlate. This exploratory study investigated how mind wandering and daydreaming are related to different aspects of sleep quality, and whether sleep quality influences the relationships between mind wandering/daydreaming and negative affect, and mind wandering/daydreaming and chronotype. Three surveys (Ns = 213; 190; 270) were completed with Chinese adults aged 18–50, including measures of sleep quality, daytime sleepiness, mind wandering, daydreaming, chronotype and affect (positive and negative). Higher frequencies of mind wandering and daydreaming were associated with poorer sleep quality, in particular with poor subjective sleep quality and increased sleep latency, night-time disturbance, daytime dysfunction and daytime sleepiness. Poor sleep quality was found to partially mediate the relationships between daydreaming and negative affect, and mind wandering and negative affect. Additionally, low positive affect and poor sleep quality, in conjunction, fully mediated the relationships between chronotype and mind wandering, and chronotype and daydreaming. The relationships between mind wandering/daydreaming and positive affect were also moderated by chronotype, being weaker in those with a morning preference. Finally, while daytime sleepiness was positively correlated with daydream frequency, it was negatively correlated with a measure of problem-solving daydreams, indicating that more refined distinctions between different forms of daydreaming or mind wandering are warranted. Overall, the evidence is suggestive of a bi-directional relationship between poor sleep quality and mind wandering/daydreaming, which may be

  12. Retinal image quality assessment using generic features

    NASA Astrophysics Data System (ADS)

    Fasih, Mahnaz; Langlois, J. M. Pierre; Ben Tahar, Houssem; Cheriet, Farida

    2014-03-01

    Retinal image quality assessment is an important step in automated eye disease diagnosis. Diagnosis accuracy is highly dependent on the quality of retinal images, because poor image quality might prevent the observation of significant eye features and disease manifestations. A robust algorithm is therefore required in order to evaluate the quality of images in a large database. We developed an algorithm for retinal image quality assessment based on generic features that is independent from segmentation methods. It exploits the local sharpness and texture features by applying the cumulative probability of blur detection metric and run-length encoding algorithm, respectively. The quality features are combined to evaluate the image's suitability for diagnosis purposes. Based on the recommendations of medical experts and our experience, we compared a global and a local approach. A support vector machine with radial basis functions was used as a nonlinear classifier in order to classify images to gradable and ungradable groups. We applied our methodology to 65 images of size 2592×1944 pixels that had been graded by a medical expert. The expert evaluated 38 images as gradable and 27 as ungradable. The results indicate very good agreement between the proposed algorithm's predictions and the medical expert's judgment: the sensitivity and specificity for the local approach are respectively 92% and 94%. The algorithm demonstrates sufficient robustness to identify relevant images for automated diagnosis.

  13. Perceived quality of wood images influenced by the skewness of image histogram

    NASA Astrophysics Data System (ADS)

    Katsura, Shigehito; Mizokami, Yoko; Yaguchi, Hirohisa

    2015-08-01

    The shape of image luminance histograms is related to material perception. We investigated how the luminance histogram contributed to improvements in the perceived quality of wood images by examining various natural wood and adhesive vinyl sheets with printed wood grain. In the first experiment, we visually evaluated the perceived quality of wood samples. In addition, we measured the colorimetric parameters of the wood samples and calculated statistics of image luminance. The relationship between visual evaluation scores and image statistics suggested that skewness and kurtosis affected the perceived quality of wood. In the second experiment, we evaluated the perceived quality of wood images with altered luminance skewness and kurtosis using a paired comparison method. Our result suggests that wood images are more realistic if the skewness of the luminance histogram is slightly negative.

  14. Seven challenges for image quality research

    NASA Astrophysics Data System (ADS)

    Chandler, Damon M.; Alam, Md M.; Phan, Thien D.

    2014-02-01

    Image quality assessment has been a topic of recent intense research due to its usefulness in a wide variety of applications. Owing in large part to efforts within the HVEI community, image-quality research has particularly benefited from improved models of visual perception. However, over the last decade, research in image quality has largely shifted from the previous broader objective of gaining a better understanding of human vision, to the current limited objective of better fitting the available ground-truth data. In this paper, we discuss seven open challenges in image quality research. These challenges stem from lack of complete perceptual models for: natural images; suprathreshold distortions; interactions between distortions and images; images containing multiple and nontraditional distortions; and images containing enhancements. We also discuss challenges related to computational efficiency. The objective of this paper is not only to highlight the limitations in our current knowledge of image quality, but to also emphasize the need for additional fundamental research in quality perception.

  15. Improving high resolution retinal image quality using speckle illumination HiLo imaging

    PubMed Central

    Zhou, Xiaolin; Bedggood, Phillip; Metha, Andrew

    2014-01-01

    Retinal image quality from flood illumination adaptive optics (AO) ophthalmoscopes is adversely affected by out-of-focus light scatter due to the lack of confocality. This effect is more pronounced in small eyes, such as that of rodents, because the requisite high optical power confers a large dioptric thickness to the retina. A recently-developed structured illumination microscopy (SIM) technique called HiLo imaging has been shown to reduce the effect of out-of-focus light scatter in flood illumination microscopes and produce pseudo-confocal images with significantly improved image quality. In this work, we adopted the HiLo technique to a flood AO ophthalmoscope and performed AO imaging in both (physical) model and live rat eyes. The improvement in image quality from HiLo imaging is shown both qualitatively and quantitatively by using spatial spectral analysis. PMID:25136486

  16. Combined terahertz imaging system for enhanced imaging quality

    NASA Astrophysics Data System (ADS)

    Dolganova, Irina N.; Zaytsev, Kirill I.; Metelkina, Anna A.; Yakovlev, Egor V.; Karasik, Valeriy E.; Yurchenko, Stanislav O.

    2016-06-01

    An improved terahertz (THz) imaging system is proposed for enhancing image quality. Imaging scheme includes THz source and detection system operated in active mode as well as in passive one. In order to homogeneously illuminate the object plane the THz reshaper is proposed. The form and internal structure of the reshaper were studied by the numerical simulation. Using different test-objects we compare imaging quality in active and passive THz imaging modes. Imaging contrast and modulation transfer functions in active and passive imaging modes show drawbacks of them in high and low spatial frequencies, respectively. The experimental results confirm the benefit of combining both imaging modes into hybrid one. The proposed algorithm of making hybrid THz image is an effective approach of retrieving maximum information about the remote object.

  17. Automatic quality assessment of planetary images

    NASA Astrophysics Data System (ADS)

    Sidiropoulos, P.; Muller, J.-P.

    2015-10-01

    A significant fraction of planetary images are corrupted beyond the point that much scientific meaning can be extracted. For example, transmission errors result in missing data which is unrecoverable. The available planetary image datasets include many such "bad data", which both occupy valuable scientific storage resources and create false impressions about planetary image availability for specific planetary objects or target areas. In this work, we demonstrate a pipeline that we have developed to automatically assess the quality of planetary images. Additionally, this method discriminates between different types of image degradation, such as low-quality originating from camera flaws or low-quality triggered by atmospheric conditions, etc. Examples of quality assessment results for Viking Orbiter imagery will be also presented.

  18. Perceptual image quality: Effects of tone characteristics

    PubMed Central

    Delahunt, Peter B.; Zhang, Xuemei; Brainard, David H.

    2007-01-01

    Tone mapping refers to the conversion of luminance values recorded by a digital camera or other acquisition device, to the luminance levels available from an output device, such as a monitor or a printer. Tone mapping can improve the appearance of rendered images. Although there are a variety of algorithms available, there is little information about the image tone characteristics that produce pleasing images. We devised an experiment where preferences for images with different tone characteristics were measured. The results indicate that there is a systematic relation between image tone characteristics and perceptual image quality for images containing faces. For these images, a mean face luminance level of 46–49 CIELAB L* units and a luminance standard deviation (taken over the whole image) of 18 CIELAB L* units produced the best renderings. This information is relevant for the design of tone-mapping algorithms, particularly as many images taken by digital camera users include faces. PMID:17235365

  19. Image Quality Ranking Method for Microscopy.

    PubMed

    Koho, Sami; Fazeli, Elnaz; Eriksson, John E; Hänninen, Pekka E

    2016-01-01

    Automated analysis of microscope images is necessitated by the increased need for high-resolution follow up of events in time. Manually finding the right images to be analyzed, or eliminated from data analysis are common day-to-day problems in microscopy research today, and the constantly growing size of image datasets does not help the matter. We propose a simple method and a software tool for sorting images within a dataset, according to their relative quality. We demonstrate the applicability of our method in finding good quality images in a STED microscope sample preparation optimization image dataset. The results are validated by comparisons to subjective opinion scores, as well as five state-of-the-art blind image quality assessment methods. We also show how our method can be applied to eliminate useless out-of-focus images in a High-Content-Screening experiment. We further evaluate the ability of our image quality ranking method to detect out-of-focus images, by extensive simulations, and by comparing its performance against previously published, well-established microscopy autofocus metrics. PMID:27364703

  20. Image Quality Ranking Method for Microscopy

    PubMed Central

    Koho, Sami; Fazeli, Elnaz; Eriksson, John E.; Hänninen, Pekka E.

    2016-01-01

    Automated analysis of microscope images is necessitated by the increased need for high-resolution follow up of events in time. Manually finding the right images to be analyzed, or eliminated from data analysis are common day-to-day problems in microscopy research today, and the constantly growing size of image datasets does not help the matter. We propose a simple method and a software tool for sorting images within a dataset, according to their relative quality. We demonstrate the applicability of our method in finding good quality images in a STED microscope sample preparation optimization image dataset. The results are validated by comparisons to subjective opinion scores, as well as five state-of-the-art blind image quality assessment methods. We also show how our method can be applied to eliminate useless out-of-focus images in a High-Content-Screening experiment. We further evaluate the ability of our image quality ranking method to detect out-of-focus images, by extensive simulations, and by comparing its performance against previously published, well-established microscopy autofocus metrics. PMID:27364703

  1. Image Quality Ranking Method for Microscopy

    NASA Astrophysics Data System (ADS)

    Koho, Sami; Fazeli, Elnaz; Eriksson, John E.; Hänninen, Pekka E.

    2016-07-01

    Automated analysis of microscope images is necessitated by the increased need for high-resolution follow up of events in time. Manually finding the right images to be analyzed, or eliminated from data analysis are common day-to-day problems in microscopy research today, and the constantly growing size of image datasets does not help the matter. We propose a simple method and a software tool for sorting images within a dataset, according to their relative quality. We demonstrate the applicability of our method in finding good quality images in a STED microscope sample preparation optimization image dataset. The results are validated by comparisons to subjective opinion scores, as well as five state-of-the-art blind image quality assessment methods. We also show how our method can be applied to eliminate useless out-of-focus images in a High-Content-Screening experiment. We further evaluate the ability of our image quality ranking method to detect out-of-focus images, by extensive simulations, and by comparing its performance against previously published, well-established microscopy autofocus metrics.

  2. End-to-end image quality assessment

    NASA Astrophysics Data System (ADS)

    Raventos, Joaquin

    2012-05-01

    An innovative computerized benchmarking approach (US Patent pending Sep 2011) based on extensive application of photometry, geometrical optics, and digital media using a randomized target, for a standard observer to assess the image quality of video imaging systems, at different day time, and low-light luminance levels. It takes into account, the target's contrast and color characteristics, as well as the observer's visual acuity and dynamic response. This includes human vision as part of the "extended video imaging system" (EVIS), and allows image quality assessment by several standard observers simultaneously.

  3. No-reference stereoscopic image quality assessment

    NASA Astrophysics Data System (ADS)

    Akhter, Roushain; Parvez Sazzad, Z. M.; Horita, Y.; Baltes, J.

    2010-02-01

    Display of stereo images is widely used to enhance the viewing experience of three-dimensional imaging and communication systems. In this paper, we propose a method for estimating the quality of stereoscopic images using segmented image features and disparity. This method is inspired by the human visual system. We believe the perceived distortion and disparity of any stereoscopic display is strongly dependent on local features, such as edge (non-plane) and non-edge (plane) areas. Therefore, a no-reference perceptual quality assessment is developed for JPEG coded stereoscopic images based on segmented local features of artifacts and disparity. Local feature information such as edge and non-edge area based relative disparity estimation, as well as the blockiness and the blur within the block of images are evaluated in this method. Two subjective stereo image databases are used to evaluate the performance of our method. The subjective experiments results indicate our model has sufficient prediction performance.

  4. Factors Affecting Cirrus-HD OCT Optic Disc Scan Quality: A Review with Case Examples

    PubMed Central

    Hardin, Joshua S.; Taibbi, Giovanni; Nelson, Seth C.; Chao, Diana; Vizzeri, Gianmarco

    2015-01-01

    Spectral-domain OCT is an established tool to assist clinicians in detecting glaucoma and monitor disease progression. The widespread use of this imaging modality is due, at least in part, to continuous hardware and software advancements. However, recent evidence indicates that OCT scan artifacts are frequently encountered in clinical practice. Poor image quality invariably challenges the interpretation of test results, with potential implications for the care of glaucoma patients. Therefore, adequate knowledge of various imaging artifacts is necessary. In this work, we describe several factors affecting Cirrus HD-OCT optic disc scan quality and their effects on measurement variability. PMID:26351574

  5. Analysis of the Effects of Image Quality on Digital Map Generation from Satellite Images

    NASA Astrophysics Data System (ADS)

    Kim, H.; Kim, D.; Kim, S.; Kim, T.

    2012-07-01

    High resolution satellite images are widely used to produce and update a digital map since they became widely available. It is well known that the accuracy of digital map produced from satellite images is decided largely by the accuracy of geometric modelling. However digital maps are made by a series of photogrammetric workflow. Therefore the accuracy of digital maps are also affected by the quality of satellite images, such as image interpretability. For satellite images, parameters such as Modulation Transfer Function(MTF), Signal to Noise Ratio(SNR) and Ground Sampling Distance(GSD) are used to present images quality. Our previous research stressed that such quality parameters may not represent the quality of image products such as digital maps and that parameters for image interpretability such as Ground Resolved Distance(GRD) and National Imagery Interpretability Rating Scale(NIIRS) need to be considered. In this study, we analyzed the effects of the image quality on accuracy of digital maps produced by satellite images. QuickBird, IKONOS and KOMPSAT-2 imagery were used to analyze as they have similar GSDs. We measured various image quality parameters mentioned above from these images. Then we produced digital maps from the images using a digital photogrammetric workstation. We analyzed the accuracy of the digital maps in terms of their location accuracy and their level of details. Then we compared the correlation between various image quality parameters and the accuracy of digital maps. The results of this study showed that GRD and NIIRS were more critical for map production then GSD, MTF or SNR.

  6. Rendered virtual view image objective quality assessment

    NASA Astrophysics Data System (ADS)

    Lu, Gang; Li, Xiangchun; Zhang, Yi; Peng, Kai

    2013-08-01

    The research on rendered virtual view image (RVVI) objective quality assessment is important for integrated imaging system and image quality assessment (IQA). Traditional IQA algorithms cannot be applied directly on the system receiver-side due to interview displacement and the absence of original reference. This study proposed a block-based neighbor reference (NbR) IQA framework for RVVI IQA. Neighbor views used for rendering are employed for quality assessment in the proposed framework. A symphonious factor handling noise and interview displacement is defined and applied to evaluate the contribution of the obtained quality index in each block pair. A three-stage experiment scheme is also presented to testify the proposed framework and evaluate its homogeneity performance when comparing to full reference IQA. Experimental results show the proposed framework is useful in RVVI objective quality assessment at system receiver-side and benchmarking different rendering algorithms.

  7. Continuous assessment of perceptual image quality

    NASA Astrophysics Data System (ADS)

    Hamberg, Roelof; de Ridder, Huib

    1995-12-01

    The study addresses whether subjects are able to assess the perceived quality of an image sequence continuously. To this end, a new method for assessing time-varying perceptual image quality is presented by which subjects continuously indicate the perceived strength of image quality by moving a slider along a graphical scale. The slider's position on this scale is sampled every second. In this way, temporal variations in quality can be monitored quantitatively, and a means is provided by which differences between, for example, alternative transmission systems can be analyzed in an informative way. The usability of this method is illustrated by an experiment in which, for a period of 815 s, subjects assessed the quality of still pictures comprising time-varying degrees of sharpness. Copyright (c) 1995 Optical Society of America

  8. Quality measures in applications of image restoration.

    PubMed

    Kriete, A; Naim, M; Schafer, L

    2001-01-01

    We describe a new method for the estimation of image quality in image restoration applications. We demonstrate this technique on a simulated data set of fluorescent beads, in comparison with restoration by three different deconvolution methods. Both the number of iterations and a regularisation factor are varied to enforce changes in the resulting image quality. First, the data sets are directly compared by an accuracy measure. These values serve to validate the image quality descriptor, which is developed on the basis of optical information theory. This most general measure takes into account the spectral energies and the noise, weighted in a logarithmic fashion. It is demonstrated that this method is particularly helpful as a user-oriented method to control the output of iterative image restorations and to eliminate the guesswork in choosing a suitable number of iterations. PMID:11587324

  9. Toward clinically relevant standardization of image quality.

    PubMed

    Samei, Ehsan; Rowberg, Alan; Avraham, Ellie; Cornelius, Craig

    2004-12-01

    In recent years, notable progress has been made on standardization of medical image presentations in the definition and implementation of the Digital Imaging and Communications in Medicine (DICOM) Grayscale Standard Display Function (GSDF). In parallel, the American Association of Physicists in Medicine (AAPM) Task Group 18 has provided much needed guidelines and tools for visual and quantitative assessment of medical display quality. In spite of these advances, however, there are still notable gaps in the effectiveness of DICOM GSDF to assure consistent and high-quality display of medical images. In additions the degree of correlation between display technical data and diagnostic usability and performance of displays remains unclear. This article proposes three specific steps that DICOM, AAPM, and ACR may collectively take to bridge the gap between technical performance and clinical use: (1) DICOM does not provide means and acceptance criteria to evaluate the conformance of a display device to GSDF or to address other image quality characteristics. DICOM can expand beyond luminance response, extending the measurable, quantifiable elements of TG18 such as reflection and resolution. (2) In a large picture archiving and communication system (PACS) installation, it is critical to continually track the appropriate use and performance of multiple display devices. DICOM may help with this task by adding a Device Service Class to the standard to provide for communication and control of image quality parameters between applications and devices, (3) The question of clinical significance of image quality metrics has rarely been addressed by prior efforts. In cooperation with AAPM, the American College of Radiology (ACR), and the Society for Computer Applications in Radiology (SCAR), DICOM may help to initiate research that will determine the clinical consequence of variations in image quality metrics (eg, GSDF conformance) and to define what constitutes image quality from a

  10. Image quality evaluation using moving targets

    NASA Astrophysics Data System (ADS)

    Artmann, Uwe

    2013-03-01

    The basic concept of testing a digital imaging device is to reproduce a known target and to analyze the resulting image. This semi-reference approach can be used for various different aspects of image quality. Each part of the imaging chain can have an influence on the results: lens, sensor, image processing and the target itself. The results are valid only for the complete system. If we want to test a single component, we have to make sure that we change only one and keep all others constant. When testing mobile imaging devices, we run into the problem that hardly anything can be manually controlled by the tester. Manual exposure control is not available for most devices, the focus cannot be influenced and hardly any settings for the image processing are available. Due to the limitations in the hardware, the image pipeline in the digital signal processor (DSP) of mobile imaging devices is a critical part of the image quality evaluation. The processing power of the DSPs allows sharpening, tonal correction and noise reduction to be non-linear and adaptive. This makes it very hard to describe the behavior for an objective image quality evaluation. The image quality is highly influenced by the signal processing for noise and resolution and the processing is the main reason for the loss of low contrast, _ne details, the so called texture blur. We present our experience to describe the image processing in more detail. All standardized test methods use a defined chart and require, that the chart and the camera are not moved in any way during test. In this paper, we present our results investigating the influence of chart movement during the test. Different structures, optimized for different aspects of image quality evaluation, are moved with a defined speed during the capturing process. The chart movement will change the input for the signal processing depending on the speed of the target during the test. The basic theoretical changes in the image will be the

  11. Propagation, structural similarity, and image quality

    NASA Astrophysics Data System (ADS)

    Pérez, Jorge; Mas, David; Espinosa, Julián; Vázquez, Carmen; Illueca, Carlos

    2012-06-01

    Retinal image quality is usually analysed through different parameters typical from instrumental optics, i.e, PSF, MTF and wavefront aberrations. Although these parameters are important, they are hard to translate to visual quality parameters since human vision exhibits some tolerance to certain aberrations. This is particularly important in postsurgery eyes, where non-common aberration are induced and their effects on the final image quality is not clear. Natural images usually show a strong dependency between one point and its neighbourhood. This fact helps to the image interpretation and should be considered when determining the final image quality. The aim of this work is to propose an objective index which allows comparing natural images on the retina and, from them, to obtain relevant information abut the visual quality of a particular subject. To this end, we propose a individual eye modelling. The morphological data of the subject's eye are considered and the light propagation through the ocular media is calculated by means of a Fourier-transform-based method. The retinal PSF so obtained is convolved with the natural scene under consideration and the obtained image is compared with the ideal one by using the structural similarity index. The technique is applied on 2 eyes with a multifocal corneal profile (PresbyLasik) and can be used to determine the real extension of the achieved pseudoaccomodation.

  12. No training blind image quality assessment

    NASA Astrophysics Data System (ADS)

    Chu, Ying; Mou, Xuanqin; Ji, Zhen

    2014-03-01

    State of the art blind image quality assessment (IQA) methods generally extract perceptual features from the training images, and send them into support vector machine (SVM) to learn the regression model, which could be used to further predict the quality scores of the testing images. However, these methods need complicated training and learning, and the evaluation results are sensitive to image contents and learning strategies. In this paper, two novel blind IQA metrics without training and learning are firstly proposed. The new methods extract perceptual features, i.e., the shape consistency of conditional histograms, from the joint histograms of neighboring divisive normalization transform coefficients of distorted images, and then compare the length attribute of the extracted features with that of the reference images and degraded images in the LIVE database. For the first method, a cluster center is found in the feature attribute space of the natural reference images, and the distance between the feature attribute of the distorted image and the cluster center is adopted as the quality label. The second method utilizes the feature attributes and subjective scores of all the images in the LIVE database to construct a dictionary, and the final quality score is calculated by interpolating the subjective scores of nearby words in the dictionary. Unlike the traditional SVM based blind IQA methods, the proposed metrics have explicit expressions, which reflect the relationships of the perceptual features and the image quality well. Experiment results in the publicly available databases such as LIVE, CSIQ and TID2008 had shown the effectiveness of the proposed methods, and the performances are fairly acceptable.

  13. Image Acquisition and Quality in Digital Radiography.

    PubMed

    Alexander, Shannon

    2016-09-01

    Medical imaging has undergone dramatic changes and technological breakthroughs since the introduction of digital radiography. This article presents information on the development of digital radiography and types of digital radiography systems. Aspects of image quality and radiation exposure control are highlighted as well. In addition, the article includes related workplace changes and medicolegal considerations in the digital radiography environment. PMID:27601691

  14. Holographic projection with higher image quality.

    PubMed

    Qu, Weidong; Gu, Huarong; Tan, Qiaofeng

    2016-08-22

    The spatial resolution limited by the size of the spatial light modulator (SLM) in the holographic projection can hardly be increased, and speckle noise always appears to induce the degradation of image quality. In this paper, the holographic projection with higher image quality is presented. The spatial resolution of the reconstructed image is 2 times of that of the existing holographic projection, and speckles are suppressed well at the same time. Finally, the effectiveness of the holographic projection is verified in experiments. PMID:27557197

  15. Validation of no-reference image quality index for the assessment of digital mammographic images

    NASA Astrophysics Data System (ADS)

    de Oliveira, Helder C. R.; Barufaldi, Bruno; Borges, Lucas R.; Gabarda, Salvador; Bakic, Predrag R.; Maidment, Andrew D. A.; Schiabel, Homero; Vieira, Marcelo A. C.

    2016-03-01

    To ensure optimal clinical performance of digital mammography, it is necessary to obtain images with high spatial resolution and low noise, keeping radiation exposure as low as possible. These requirements directly affect the interpretation of radiologists. The quality of a digital image should be assessed using objective measurements. In general, these methods measure the similarity between a degraded image and an ideal image without degradation (ground-truth), used as a reference. These methods are called Full-Reference Image Quality Assessment (FR-IQA). However, for digital mammography, an image without degradation is not available in clinical practice; thus, an objective method to assess the quality of mammograms must be performed without reference. The purpose of this study is to present a Normalized Anisotropic Quality Index (NAQI), based on the Rényi entropy in the pseudo-Wigner domain, to assess mammography images in terms of spatial resolution and noise without any reference. The method was validated using synthetic images acquired through an anthropomorphic breast software phantom, and the clinical exposures on anthropomorphic breast physical phantoms and patient's mammograms. The results reported by this noreference index follow the same behavior as other well-established full-reference metrics, e.g., the peak signal-to-noise ratio (PSNR) and structural similarity index (SSIM). Reductions of 50% on the radiation dose in phantom images were translated as a decrease of 4dB on the PSNR, 25% on the SSIM and 33% on the NAQI, evidencing that the proposed metric is sensitive to the noise resulted from dose reduction. The clinical results showed that images reduced to 53% and 30% of the standard radiation dose reported reductions of 15% and 25% on the NAQI, respectively. Thus, this index may be used in clinical practice as an image quality indicator to improve the quality assurance programs in mammography; hence, the proposed method reduces the subjectivity

  16. Perceptual image quality and telescope performance ranking

    NASA Astrophysics Data System (ADS)

    Lentz, Joshua K.; Harvey, James E.; Marshall, Kenneth H.; Salg, Joseph; Houston, Joseph B.

    2010-08-01

    Launch Vehicle Imaging Telescopes (LVIT) are expensive, high quality devices intended for improving the safety of vehicle personnel, ground support, civilians, and physical assets during launch activities. If allowed to degrade from the combination of wear, environmental factors, and ineffective or inadequate maintenance, these devices lose their ability to provide adequate quality imagery to analysts to prevent catastrophic events such as the NASA Space Shuttle, Challenger, accident in 1986 and the Columbia disaster of 2003. A software tool incorporating aberrations and diffraction that was developed for maintenance evaluation and modeling of telescope imagery is presented. This tool provides MTF-based image quality metric outputs which are correlated to ascent imagery analysts' perception of image quality, allowing a prediction of usefulness of imagery which would be produced by a telescope under different simulated conditions.

  17. Color image attribute and quality measurements

    NASA Astrophysics Data System (ADS)

    Gao, Chen; Panetta, Karen; Agaian, Sos

    2014-05-01

    Color image quality measures have been used for many computer vision tasks. In practical applications, the no-reference (NR) measures are desirable because reference images are not always accessible. However, only limited success has been achieved. Most existing NR quality assessments require that the types of image distortion is known a-priori. In this paper, three NR color image attributes: colorfulness, sharpness and contrast are quantified by new metrics. Using these metrics, a new Color Quality Measure (CQM), which is based on the linear combination of these three color image attributes, is presented. We evaluated the performance of several state-of-the-art no-reference measures for comparison purposes. Experimental results demonstrate the CQM correlates well with evaluations obtained from human observers and it operates in real time. The results also show that the presented CQM outperforms previous works with respect to ranking image quality among images containing the same or different contents. Finally, the performance of CQM is independent of distortion types, which is demonstrated in the experimental results.

  18. Computerized measurement of mammographic display image quality

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.; Sivarudrappa, Mahesh; Roehrig, Hans

    1999-05-01

    Since the video monitor is widely believed to be the weak link in the imaging chain, it is critical, to include it in the total image quality evaluation. Yet, most physical measurements of mammographic image quality are presently limited to making measurements on the digital matrix, not the displayed image. A method is described to quantitatively measure image quality of mammographic monitors using ACR phantom-based test patterns. The image of the test pattern is digitized using a charge coupled device (CCD) camera, and the resulting image file is analyzed by an existing phantom analysis method (Computer Analysis of Mammography Phantom Images, CAMPI). The new method is called CCD-CAMPI and it yields the Signal-to-Noise-Ratio (SNR) for an arbitrary target shape (e.g., speck, mass or fiber). In this work we show the feasibility of this idea for speck targets. Also performed were physical image quality characterization of the monitor (so-called Fourier measures) and analysis by another template matching method due to Tapiovaara and Wagner (TW) which is closely related to CAMPI. The methods were applied to a MegaScan monitor. Test patterns containing a complete speck group superposed on a noiseless background were displayed on the monitor and a series of CCD images were acquired. These images were subjected to CCD-CAMPI and TW analyses. It was found that the SNR values for the CCD-CAMPI method tracked those of the TW method, although the latter measurements were considerably less precise. The TW SNR measure was also about 25% larger than the CCD-CAMPI determination. These differences could be understood from the manner in which the two methods evaluate the noise. Overall accuracy of the CAMPI SNR determination was 4.1% for single images when expressed as a coefficient of variance. While the SNR measures are predictable from the Fourier measures the number of images and effort required is prohibitive and it is not suited to Quality Control (QC). Unlike the Fourier

  19. A database for spectral image quality

    NASA Astrophysics Data System (ADS)

    Le Moan, Steven; George, Sony; Pedersen, Marius; Blahová, Jana; Hardeberg, Jon Yngve

    2015-01-01

    We introduce a new image database dedicated to multi-/hyperspectral image quality assessment. A total of nine scenes representing pseudo-at surfaces of different materials (textile, wood, skin. . . ) were captured by means of a 160 band hyperspectral system with a spectral range between 410 and 1000nm. Five spectral distortions were designed, applied to the spectral images and subsequently compared in a psychometric experiment, in order to provide a basis for applications such as the evaluation of spectral image difference measures. The database can be downloaded freely from http://www.colourlab.no/cid.

  20. Investigation of perceptual attributes for mobile display image quality

    NASA Astrophysics Data System (ADS)

    Gong, Rui; Xu, Haisong; Wang, Qing; Wang, Zhehong; Li, Haifeng

    2013-08-01

    Large-scale psychophysical experiments are carried out on two types of mobile displays to evaluate the perceived image quality (IQ). Eight perceptual attributes, i.e., naturalness, colorfulness, brightness, contrast, sharpness, clearness, preference, and overall IQ, are visually assessed via categorical judgment method for various application types of test images, which were manipulated by different methods. Their correlations are deeply discussed, and further factor analysis revealed the two essential components to describe the overall IQ, i.e., the component of image detail aspect and the component of color information aspect. Clearness and naturalness are regarded as two principal factors for natural scene images, whereas clearness and colorfulness were selected as key attributes affecting the overall IQ for other application types of images. Accordingly, based on these selected attributes, two kinds of empirical models are built to predict the overall IQ of mobile displays for different application types of images.

  1. Measuring image quality performance on image versions saved with different file format and compression ratio

    NASA Astrophysics Data System (ADS)

    Mitjà, Carles; Escofet, Jaume; Bover, Toni

    2012-06-01

    Digitization of existing documents containing images is an important body of work for many archives ranging from individuals to institutional organizations. The methods and file formats used in this digitization is usually a trade off between budget, file volume size and image quality, while not necessarily in this order. The use of most commons and standardized file formats, JPEG and TIFF, prompts the operator to decide the compression ratio that affects both the final file volume size and the quality of the resulting image version. The evaluation of the image quality achieved by a system can be done by means of several measures and methods, being the Modulation Transfer Function (MTF) one of most used. The methods employed by the compression algorithms affect in a different way the two basic features of the image contents, edges and textures. Those basic features are too differently affected by the amount of noise generated at the digitization stage. Therefore, the target used in the measurement should be related with the features usually presents in general imaging. This work presents a comparison between the results obtained by measuring the MTF of images taken with a professional camera system and saved in several file formats compression ratios. In order to accomplish with the needs early stated, the MTF measurement has been done by two separate methods using the slanted edge and dead leaves targets respectively. The measurement results are shown and compared related with the respective file volume size.

  2. Blind image quality assessment through anisotropy.

    PubMed

    Gabarda, Salvador; Cristóbal, Gabriel

    2007-12-01

    We describe an innovative methodology for determining the quality of digital images. The method is based on measuring the variance of the expected entropy of a given image upon a set of predefined directions. Entropy can be calculated on a local basis by using a spatial/spatial-frequency distribution as an approximation for a probability density function. The generalized Rényi entropy and the normalized pseudo-Wigner distribution (PWD) have been selected for this purpose. As a consequence, a pixel-by-pixel entropy value can be calculated, and therefore entropy histograms can be generated as well. The variance of the expected entropy is measured as a function of the directionality, and it has been taken as an anisotropy indicator. For this purpose, directional selectivity can be attained by using an oriented 1-D PWD implementation. Our main purpose is to show how such an anisotropy measure can be used as a metric to assess both the fidelity and quality of images. Experimental results show that an index such as this presents some desirable features that resemble those from an ideal image quality function, constituting a suitable quality index for natural images. Namely, in-focus, noise-free natural images have shown a maximum of this metric in comparison with other degraded, blurred, or noisy versions. This result provides a way of identifying in-focus, noise-free images from other degraded versions, allowing an automatic and nonreference classification of images according to their relative quality. It is also shown that the new measure is well correlated with classical reference metrics such as the peak signal-to-noise ratio. PMID:18059913

  3. Monotonic correlation analysis of image quality measures for image fusion

    NASA Astrophysics Data System (ADS)

    Kaplan, Lance M.; Burks, Stephen D.; Moore, Richard K.; Nguyen, Quang

    2008-04-01

    The next generation of night vision goggles will fuse image intensified and long wave infra-red to create a hybrid image that will enable soldiers to better interpret their surroundings during nighttime missions. Paramount to the development of such goggles is the exploitation of image quality (IQ) measures to automatically determine the best image fusion algorithm for a particular task. This work introduces a novel monotonic correlation coefficient to investigate how well possible IQ features correlate to actual human performance, which is measured by a perception study. The paper will demonstrate how monotonic correlation can identify worthy features that could be overlooked by traditional correlation values.

  4. Factors Affecting Quality Enhancement Procedures for E-Learning Courses

    ERIC Educational Resources Information Center

    Jara, Magdalena; Mellar, Harvey

    2009-01-01

    Purpose: This paper reports on an empirical study exploring the way in which campus-based higher education institutions (HEIs) in the UK apply their internal quality assurance and enhancement (QA/QE) procedures to their e-learning courses. The purpose of this paper is to identify those characteristics of e-learning courses which affected the…

  5. Preslaughter factors affecting poultry meat quality chapter 2.

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Poultry meat quality is affected by numerous antemortem factors, in particular those occurring during the last 24 hours that the bird is alive. These short term factors influence carcass yield (live shrink), carcass defects (bruising, broken/dislocated bones), carcass microbiological contamination, ...

  6. CULTURAL SYSTEM AFFECTS FRUIT QUALITY AND ANTIOXIDANT CAPACITY IN STRAWBERRIES

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cultural system [hill plasticulture (HC) vs. matted row (MR)] and genotypes interactions affected strawberry fruit quality. In general, fruit soluble content, total sugar, fructose, glucose, ascorbic acid, titratable acid and citric acid content were increased in the HC system. Fruit from HC also ...

  7. Neighborhood Perceptions Affect Dietary Behaviors and Diet Quality

    ERIC Educational Resources Information Center

    Keita, Akilah Dulin; Casazza, Krista; Thomas, Olivia; Fernandez, Jose R.

    2011-01-01

    Objective: The primary purpose of this study was to determine if perceived neighborhood disorder affected dietary quality within a multiethnic sample of children. Design: Children were recruited through the use of fliers, wide-distribution mailers, parent magazines, and school presentations from June 2005 to December 2008. Setting:…

  8. Effects of task and image properties on visual-attention deployment in image-quality assessment

    NASA Astrophysics Data System (ADS)

    Alers, Hani; Redi, Judith; Liu, Hantao; Heynderickx, Ingrid

    2015-03-01

    It is important to understand how humans view images and how their behavior is affected by changes in the properties of the viewed images and the task they are given, particularly the task of scoring the image quality (IQ). This is a complex behavior that holds great importance for the field of image-quality research. This work builds upon 4 years of research work spanning three databases studying image-viewing behavior. Using eye-tracking equipment, it was possible to collect information on human viewing behavior of different kinds of stimuli and under different experimental settings. This work performs a cross-analysis on the results from all these databases using state-of-the-art similarity measures. The results strongly show that asking the viewers to score the IQ significantly changes their viewing behavior. Also muting the color saturation seems to affect the saliency of the images. However, a change in IQ was not consistently found to modify visual attention deployment, neither under free looking nor during scoring. These results are helpful in gaining a better understanding of image viewing behavior under different conditions. They also have important implications on work that collects subjective image-quality scores from human observers.

  9. Subjective matters: from image quality to image psychology

    NASA Astrophysics Data System (ADS)

    Fedorovskaya, Elena A.; De Ridder, Huib

    2013-03-01

    From the advent of digital imaging through several decades of studies, the human vision research community systematically focused on perceived image quality and digital artifacts due to resolution, compression, gamma, dynamic range, capture and reproduction noise, blur, etc., to help overcome existing technological challenges and shortcomings. Technological advances made digital images and digital multimedia nearly flawless in quality, and ubiquitous and pervasive in usage, provide us with the exciting but at the same time demanding possibility to turn to the domain of human experience including higher psychological functions, such as cognition, emotion, awareness, social interaction, consciousness and Self. In this paper we will outline the evolution of human centered multidisciplinary studies related to imaging and propose steps and potential foci of future research.

  10. No-reference remote sensing image quality assessment using a comprehensive evaluation factor

    NASA Astrophysics Data System (ADS)

    Wang, Lin; Wang, Xu; Li, Xiao; Shao, Xiaopeng

    2014-05-01

    The conventional image quality assessment algorithm, such as Peak Signal to Noise Ratio (PSNR), Mean Square Error(MSE) and structural similarity (SSIM), needs the original image as a reference. It's not applicable to the remote sensing image for which the original image cannot be assumed to be available. In this paper, a No-reference Image Quality Assessment (NRIQA) algorithm is presented to evaluate the quality of remote sensing image. Since blur and noise (including the stripe noise) are the common distortion factors affecting remote sensing image quality, a comprehensive evaluation factor is modeled to assess the blur and noise by analyzing the image visual properties for different incentives combined with SSIM based on human visual system (HVS), and also to assess the stripe noise by using Phase Congruency (PC). The experiment results show this algorithm is an accurate and reliable method for Remote Sensing Image Quality Assessment.

  11. Geometric assessment of image quality using digital image registration techniques

    NASA Technical Reports Server (NTRS)

    Tisdale, G. E.

    1976-01-01

    Image registration techniques were developed to perform a geometric quality assessment of multispectral and multitemporal image pairs. Based upon LANDSAT tapes, accuracies to a small fraction of a pixel were demonstrated. Because it is insensitive to the choice of registration areas, the technique is well suited to performance in an automatic system. It may be implemented at megapixel-per-second rates using a commercial minicomputer in combination with a special purpose digital preprocessor.

  12. Image quality measures and their performance

    NASA Technical Reports Server (NTRS)

    Eskicioglu, Ahmet M.; Fisher, Paul S.; Chen, Si-Yuan

    1994-01-01

    A number of quality measures are evaluated for gray scale image compression. They are all bivariate exploiting the differences between corresponding pixels in the original and degraded images. It is shown that although some numerical measures correlate well with the observers' response for a given compression technique, they are not reliable for an evaluation across different techniques. The two graphical measures (histograms and Hosaka plots), however, can be used to appropriately specify not only the amount, but also the type of degradation in reconstructed images.

  13. Colored plastic mulch microclimates affect strawberry fruit yield and quality.

    PubMed

    Shiukhy, Saeid; Raeini-Sarjaz, Mahmoud; Chalavi, Vida

    2015-08-01

    Significant reduction of strawberry (Fragaria × ananassa, Duch.) fruit yield and quality, as a consequence of conventional cultivation method, is common in the Caspian Sea region, Iran. Recently, growers started using plastic mulches to overcome these shortcomings. Plastic mulches have different thermal and radiation properties and could affect strawberry fruit yield and quality. In the present study, the effect of different colored plastic mulches (black, red, and white) along with conventional practice was tested on yield and quality of strawberry Camarosa cultivar, in a completely randomized block design. Colored plastic mulches had highly significant effect on fruit weight, size, and phytochemical contents. In the most harvest times, mean fruit weight was significantly higher in red plastic relative to white and control treatments. Total fruit weight of plastic mulches was not significantly different, while all were statistically higher than that of control. Fruit size significantly increased over red plastic mulch. Total fruit numbers over plastic mulches were significantly higher than that of control treatment. The content of phenolic compounds was similar between treatments, while anthocyanin content, IC(50) value, and flavonoid content significantly were affected by colored plastics. In conclusion, colored plastic mulches could affect strawberry fruit weight and quality through altering strawberry thermal and radiation environment. PMID:25348886

  14. Colored plastic mulch microclimates affect strawberry fruit yield and quality

    NASA Astrophysics Data System (ADS)

    Shiukhy, Saeid; Raeini-Sarjaz, Mahmoud; Chalavi, Vida

    2015-08-01

    Significant reduction of strawberry ( Fragaria × ananassa, Duch.) fruit yield and quality, as a consequence of conventional cultivation method, is common in the Caspian Sea region, Iran. Recently, growers started using plastic mulches to overcome these shortcomings. Plastic mulches have different thermal and radiation properties and could affect strawberry fruit yield and quality. In the present study, the effect of different colored plastic mulches (black, red, and white) along with conventional practice was tested on yield and quality of strawberry Camarosa cultivar, in a completely randomized block design. Colored plastic mulches had highly significant effect on fruit weight, size, and phytochemical contents. In the most harvest times, mean fruit weight was significantly higher in red plastic relative to white and control treatments. Total fruit weight of plastic mulches was not significantly different, while all were statistically higher than that of control. Fruit size significantly increased over red plastic mulch. Total fruit numbers over plastic mulches were significantly higher than that of control treatment. The content of phenolic compounds was similar between treatments, while anthocyanin content, IC50 value, and flavonoid content significantly were affected by colored plastics. In conclusion, colored plastic mulches could affect strawberry fruit weight and quality through altering strawberry thermal and radiation environment.

  15. Quality evaluation of fruit by hyperspectral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    This chapter presents new applications of hyperspectral imaging for measuring the optical properties of fruits and assessing their quality attributes. A brief overview is given of current techniques for measuring optical properties of turbid and opaque biological materials. Then a detailed descripti...

  16. Image Quality Indicator for Infrared Inspections

    NASA Technical Reports Server (NTRS)

    Burke, Eric

    2011-01-01

    The quality of images generated during an infrared thermal inspection depends on many system variables, settings, and parameters to include the focal length setting of the IR camera lens. If any relevant parameter is incorrect or sub-optimal, the resulting IR images will usually exhibit inherent unsharpness and lack of resolution. Traditional reference standards and image quality indicators (IQIs) are made of representative hardware samples and contain representative flaws of concern. These standards are used to verify that representative flaws can be detected with the current IR system settings. However, these traditional standards do not enable the operator to quantify the quality limitations of the resulting images, i.e. determine the inherent maximum image sensitivity and image resolution. As a result, the operator does not have the ability to optimize the IR inspection system prior to data acquisition. The innovative IQI described here eliminates this limitation and enables the operator to objectively quantify and optimize the relevant variables of the IR inspection system, resulting in enhanced image quality with consistency and repeatability in the inspection application. The IR IQI consists of various copper foil features of known sizes that are printed on a dielectric non-conductive board. The significant difference in thermal conductivity between the two materials ensures that each appears with a distinct grayscale or brightness in the resulting IR image. Therefore, the IR image of the IQI exhibits high contrast between the copper features and the underlying dielectric board, which is required to detect the edges of the various copper features. The copper features consist of individual elements of various shapes and sizes, or of element-pairs of known shapes and sizes and with known spacing between the elements creating the pair. For example, filled copper circles with various diameters can be used as individual elements to quantify the image sensitivity

  17. Scene reduction for subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Lewandowska (Tomaszewska), Anna

    2016-01-01

    Evaluation of image quality is important for many image processing systems, such as those used for acquisition, compression, restoration, enhancement, or reproduction. Its measurement is often accompanied by user studies, in which a group of observers rank or rate results of several algorithms. Such user studies, known as subjective image quality assessment experiments, can be very time consuming and do not guarantee conclusive results. This paper is intended to help design an efficient and rigorous quality assessment experiment. We propose a method of limiting the number of scenes that need to be tested, which can significantly reduce the experimental effort and still capture relevant scene-dependent effects. To achieve it, we employ a clustering technique and evaluate it on the basis of compactness and separation criteria. The correlation between the results obtained from a set of images in an initial database and the results received from reduced experiment are analyzed. Finally, we propose a procedure for reducing the initial scenes number. Four different assessment techniques were tested: single stimulus, double stimulus, forced choice, and similarity judgments. We conclude that in most cases, 9 to 12 judgments per evaluated algorithm for a large scene collection is sufficient to reduce the initial set of images.

  18. Compressed image quality metric based on perceptually weighted distortion.

    PubMed

    Hu, Sudeng; Jin, Lina; Wang, Hanli; Zhang, Yun; Kwong, Sam; Kuo, C-C Jay

    2015-12-01

    Objective quality assessment for compressed images is critical to various image compression systems that are essential in image delivery and storage. Although the mean squared error (MSE) is computationally simple, it may not be accurate to reflect the perceptual quality of compressed images, which is also affected dramatically by the characteristics of human visual system (HVS), such as masking effect. In this paper, an image quality metric (IQM) is proposed based on perceptually weighted distortion in terms of the MSE. To capture the characteristics of HVS, a randomness map is proposed to measure the masking effect and a preprocessing scheme is proposed to simulate the processing that occurs in the initial part of HVS. Since the masking effect highly depends on the structural randomness, the prediction error from neighborhood with a statistical model is used to measure the significance of masking. Meanwhile, the imperceptible signal with high frequency could be removed by preprocessing with low-pass filters. The relation is investigated between the distortions before and after masking effect, and a masking modulation model is proposed to simulate the masking effect after preprocessing. The performance of the proposed IQM is validated on six image databases with various compression distortions. The experimental results show that the proposed algorithm outperforms other benchmark IQMs. PMID:26415170

  19. Effects of display rendering on HDR image quality assessment

    NASA Astrophysics Data System (ADS)

    Zerman, Emin; Valenzise, Giuseppe; De Simone, Francesca; Banterle, Francesco; Dufaux, Frederic

    2015-09-01

    High dynamic range (HDR) displays use local backlight modulation to produce both high brightness levels and large contrast ratios. Thus, the display rendering algorithm and its parameters may greatly affect HDR visual experience. In this paper, we analyze the impact of display rendering on perceived quality for a specific display (SIM2 HDR47) and for a popular application scenario, i.e., HDR image compression. To this end, we assess whether significant differences exist between subjective quality of compressed images, when these are displayed using either the built-in rendering of the display, or a rendering algorithm developed by ourselves. As a second contribution of this paper, we investigate whether the possibility to estimate the true pixel-wise luminance emitted by the display, offered by our rendering approach, can improve the performance of HDR objective quality metrics that require true pixel-wise luminance as input.

  20. Analysis of image quality based on perceptual preference

    NASA Astrophysics Data System (ADS)

    Xue, Liqin; Hua, Yuning; Zhao, Guangzhou; Qi, Yaping

    2007-11-01

    This paper deals with image quality analysis considering the impact of psychological factors involved in assessment. The attributes of image quality requirement were partitioned according to the visual perception characteristics and the preference of image quality were obtained by the factor analysis method. The features of image quality which support the subjective preference were identified, The adequacy of image is evidenced to be the top requirement issues to the display image quality improvement. The approach will be beneficial to the research of the image quality subjective quantitative assessment method.

  1. Prediction of Viking lander camera image quality

    NASA Technical Reports Server (NTRS)

    Huck, F. O.; Burcher, E. E.; Jobson, D. J.; Wall, S. D.

    1976-01-01

    Formulations are presented that permit prediction of image quality as a function of camera performance, surface radiance properties, and lighting and viewing geometry. Predictions made for a wide range of surface radiance properties reveal that image quality depends strongly on proper camera dynamic range command and on favorable lighting and viewing geometry. Proper camera dynamic range commands depend mostly on the surface albedo that will be encountered. Favorable lighting and viewing geometries depend mostly on lander orientation with respect to the diurnal sun path over the landing site, and tend to be independent of surface albedo and illumination scattering function. Side lighting with low sun elevation angles (10 to 30 deg) is generally favorable for imaging spatial details and slopes, whereas high sun elevation angles are favorable for measuring spectral reflectances.

  2. Structural similarity analysis for brain MR image quality assessment

    NASA Astrophysics Data System (ADS)

    Punga, Mirela Visan; Moldovanu, Simona; Moraru, Luminita

    2014-11-01

    Brain MR images are affected and distorted by various artifacts as noise, blur, blotching, down sampling or compression and as well by inhomogeneity. Usually, the performance of pre-processing operation is quantified by using the quality metrics as mean squared error and its related metrics such as peak signal to noise ratio, root mean squared error and signal to noise ratio. The main drawback of these metrics is that they fail to take the structural fidelity of the image into account. For this reason, we addressed to investigate the structural changes related to the luminance and contrast variation (as non-structural distortions) and to denoising process (as structural distortion)through an alternative metric based on structural changes in order to obtain the best image quality.

  3. Body image quality of life in eating disorders

    PubMed Central

    Jáuregui Lobera, Ignacio; Bolaños Ríos, Patricia

    2011-01-01

    Purpose: The objective was to examine how body image affects quality of life in an eating-disorder (ED) clinical sample, a non-ED clinical sample, and a nonclinical sample. We hypothesized that ED patients would show the worst body image quality of life. We also hypothesized that body image quality of life would have a stronger negative association with specific ED-related variables than with other psychological and psychopathological variables, mainly among ED patients. On the basis of previous studies, the influence of gender on the results was explored, too. Patients and methods: The final sample comprised 70 ED patients (mean age 22.65 ± 7.76 years; 59 women and 11 men); 106 were patients with other psychiatric disorders (mean age 28.20 ± 6.52; 67 women and 39 men), and 135 were university students (mean age 21.57 ± 2.58; 81 women and 54 men), with no psychiatric history. After having obtained informed consent, the following questionnaires were administered: Body Image Quality of Life Inventory-Spanish version (BIQLI-SP), Eating Disorders Inventory-2 (EDI-2), Perceived Stress Questionnaire (PSQ), Self-Esteem Scale (SES), and Symptom Checklist-90-Revised (SCL-90-R). Results: The ED patients’ ratings on the BIQLI-SP were the lowest and negatively scored (BIQLI-SP means: +20.18, +5.14, and −6.18, in the student group, the non-ED patient group, and the ED group, respectively). The effect of body image on quality of life was more negative in the ED group in all items of the BIQLI-SP. Body image quality of life was negatively associated with specific ED-related variables, more than with other psychological and psychopathological variables, but not especially among ED patients. Conclusion: Body image quality of life was affected not only by specific pathologies related to body image disturbances, but also by other psychopathological syndromes. Nevertheless, the greatest effect was related to ED, and seemed to be more negative among men. This finding is the

  4. The Affective Consequences of Minimizing Women's Body Image Concerns

    ERIC Educational Resources Information Center

    Bosson, Jennifer K.; Pinel, Elizabeth C.; Thompson, J. Kevin

    2008-01-01

    We propose that women regularly anticipate and receive messages from others that trivialize the severity of their body image concerns. Moreover, we suggest that these minimizing messages can heighten women's negative affective reactions to body image threats, particularly if they internalize them. Two studies provided support for these ideas. In…

  5. Physical measures of image quality in mammography

    NASA Astrophysics Data System (ADS)

    Chakraborty, Dev P.

    1996-04-01

    A recently introduced method for quantitative analysis of images of the American College of Radiology (ACR) mammography accreditation phantom has been extended to include signal- to-noise-ratio (SNR) measurements, and has been applied to survey the image quality of 54 mammography machines from 17 hospitals. Participants sent us phantom images to be evaluated for each mammography machine at their hospital. Each phantom was loaned to us for obtaining images of the wax insert plate on a reference machine at our institution. The images were digitized and analyzed to yield indices that quantified the image quality of the machines precisely. We have developed methods for normalizing for the variation of the individual speck sizes between different ACR phantoms, for the variation of the speck sizes within a microcalcification group, and for variations in overall speeds of the mammography systems. In terms of the microcalcification SNR, the variability of the x-ray machines was 40.5% when no allowance was made for phantom or mAs variations. This dropped to 17.1% when phantom variability was accounted for, and to 12.7% when mAs variability was also allowed for. Our work shows the feasibility of practical, low-cost, objective and accurate evaluations, as a useful adjunct to the present ACR method.

  6. Naturalness and interestingness of test images for visual quality evaluation

    NASA Astrophysics Data System (ADS)

    Halonen, Raisa; Westman, Stina; Oittinen, Pirkko

    2011-01-01

    Balanced and representative test images are needed to study perceived visual quality in various application domains. This study investigates naturalness and interestingness as image quality attributes in the context of test images. Taking a top-down approach we aim to find the dimensions which constitute naturalness and interestingness in test images and the relationship between these high-level quality attributes. We compare existing collections of test images (e.g. Sony sRGB images, ISO 12640 images, Kodak images, Nokia images and test images developed within our group) in an experiment combining quality sorting and structured interviews. Based on the data gathered we analyze the viewer-supplied criteria for naturalness and interestingness across image types, quality levels and judges. This study advances our understanding of subjective image quality criteria and enables the validation of current test images, furthering their development.

  7. Quantitative statistical methods for image quality assessment.

    PubMed

    Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

    2013-01-01

    Quantitative measures of image quality and reliability are critical for both qualitative interpretation and quantitative analysis of medical images. While, in theory, it is possible to analyze reconstructed images by means of Monte Carlo simulations using a large number of noise realizations, the associated computational burden makes this approach impractical. Additionally, this approach is less meaningful in clinical scenarios, where multiple noise realizations are generally unavailable. The practical alternative is to compute closed-form analytical expressions for image quality measures. The objective of this paper is to review statistical analysis techniques that enable us to compute two key metrics: resolution (determined from the local impulse response) and covariance. The underlying methods include fixed-point approaches, which compute these metrics at a fixed point (the unique and stable solution) independent of the iterative algorithm employed, and iteration-based approaches, which yield results that are dependent on the algorithm, initialization, and number of iterations. We also explore extensions of some of these methods to a range of special contexts, including dynamic and motion-compensated image reconstruction. While most of the discussed techniques were developed for emission tomography, the general methods are extensible to other imaging modalities as well. In addition to enabling image characterization, these analysis techniques allow us to control and enhance imaging system performance. We review practical applications where performance improvement is achieved by applying these ideas to the contexts of both hardware (optimizing scanner design) and image reconstruction (designing regularization functions that produce uniform resolution or maximize task-specific figures of merit). PMID:24312148

  8. Quantitative Statistical Methods for Image Quality Assessment

    PubMed Central

    Dutta, Joyita; Ahn, Sangtae; Li, Quanzheng

    2013-01-01

    Quantitative measures of image quality and reliability are critical for both qualitative interpretation and quantitative analysis of medical images. While, in theory, it is possible to analyze reconstructed images by means of Monte Carlo simulations using a large number of noise realizations, the associated computational burden makes this approach impractical. Additionally, this approach is less meaningful in clinical scenarios, where multiple noise realizations are generally unavailable. The practical alternative is to compute closed-form analytical expressions for image quality measures. The objective of this paper is to review statistical analysis techniques that enable us to compute two key metrics: resolution (determined from the local impulse response) and covariance. The underlying methods include fixed-point approaches, which compute these metrics at a fixed point (the unique and stable solution) independent of the iterative algorithm employed, and iteration-based approaches, which yield results that are dependent on the algorithm, initialization, and number of iterations. We also explore extensions of some of these methods to a range of special contexts, including dynamic and motion-compensated image reconstruction. While most of the discussed techniques were developed for emission tomography, the general methods are extensible to other imaging modalities as well. In addition to enabling image characterization, these analysis techniques allow us to control and enhance imaging system performance. We review practical applications where performance improvement is achieved by applying these ideas to the contexts of both hardware (optimizing scanner design) and image reconstruction (designing regularization functions that produce uniform resolution or maximize task-specific figures of merit). PMID:24312148

  9. No-reference image quality metric based on image classification

    NASA Astrophysics Data System (ADS)

    Choi, Hyunsoo; Lee, Chulhee

    2011-12-01

    In this article, we present a new no-reference (NR) objective image quality metric based on image classification. We also propose a new blocking metric and a new blur metric. Both metrics are NR metrics since they need no information from the original image. The blocking metric was computed by considering that the visibility of horizontal and vertical blocking artifacts can change depending on background luminance levels. When computing the blur metric, we took into account the fact that blurring in edge regions is generally more sensitive to the human visual system. Since different compression standards usually produce different compression artifacts, we classified images into two classes using the proposed blocking metric: one class that contained blocking artifacts and another class that did not contain blocking artifacts. Then, we used different quality metrics based on the classification results. Experimental results show that each metric correlated well with subjective ratings, and the proposed NR image quality metric consistently provided good performance with various types of content and distortions.

  10. Medical Imaging Image Quality Assessment with Monte Carlo Methods

    NASA Astrophysics Data System (ADS)

    Michail, C. M.; Karpetas, G. E.; Fountos, G. P.; Kalyvas, N. I.; Martini, Niki; Koukou, Vaia; Valais, I. G.; Kandarakis, I. S.

    2015-09-01

    The aim of the present study was to assess image quality of PET scanners through a thin layer chromatography (TLC) plane source. The source was simulated using a previously validated Monte Carlo model. The model was developed by using the GATE MC package and reconstructed images obtained with the STIR software for tomographic image reconstruction, with cluster computing. The PET scanner simulated in this study was the GE DiscoveryST. A plane source consisted of a TLC plate, was simulated by a layer of silica gel on aluminum (Al) foil substrates, immersed in 18F-FDG bath solution (1MBq). Image quality was assessed in terms of the Modulation Transfer Function (MTF). MTF curves were estimated from transverse reconstructed images of the plane source. Images were reconstructed by the maximum likelihood estimation (MLE)-OSMAPOSL algorithm. OSMAPOSL reconstruction was assessed by using various subsets (3 to 21) and iterations (1 to 20), as well as by using various beta (hyper) parameter values. MTF values were found to increase up to the 12th iteration whereas remain almost constant thereafter. MTF improves by using lower beta values. The simulated PET evaluation method based on the TLC plane source can be also useful in research for the further development of PET and SPECT scanners though GATE simulations.

  11. Image registration for DSA quality enhancement.

    PubMed

    Buzug, T M; Weese, J

    1998-01-01

    A generalized framework for histogram-based similarity measures is presented and applied to the image-enhancement task in digital subtraction angiography (DSA). The class of differentiable, strictly convex weighting functions is identified as suitable weightings of histograms for measuring the degree of clustering that goes along with registration. With respect to computation time, the energy similarity measure is the function of choice for the registration of mask and contrast image prior to subtraction. The robustness of the energy measure is studied for geometrical image distortions like rotation and scaling. Additionally, it is investigated how the histogram binning and inhomogeneous motion inside the templates influence the quality of the similarity measure. Finally, the registration success for the automated procedure is compared with the manually shift-corrected image pair of the head. PMID:9719851

  12. Image-Word Pairing-Congruity Effect on Affective Responses

    NASA Astrophysics Data System (ADS)

    Sanabria Z., Jorge C.; Cho, Youngil; Sambai, Ami; Yamanaka, Toshimasa

    The present study explores the effects of familiarity on affective responses (pleasure and arousal) to Japanese ad elements, based on the schema incongruity theory. Print ads showing natural scenes (landscapes) were used to create the stimuli (images and words). An empirical study was conducted to measure subjects' affective responses to image-word combinations that varied in terms of incongruity. The level of incongruity was based on familiarity levels, and was statistically determined by a variable called ‘pairing-congruity status’. The tested hypothesis proposed that even highly familiar image-word combinations, when combined incongruously, would elicit strong affective responses. Subjects assessed the stimuli using bipolar scales. The study was effective in tracing interactions between familiarity, pleasure and arousal, although the incongruous image-word combinations did not elicit the predicted strong effects on pleasure and arousal. The results suggest a need for further research incorporating kansei (i.e., creativity) into the process of stimuli selection.

  13. Dried fruits quality assessment by hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Serranti, Silvia; Gargiulo, Aldo; Bonifazi, Giuseppe

    2012-05-01

    Dried fruits products present different market values according to their quality. Such a quality is usually quantified in terms of freshness of the products, as well as presence of contaminants (pieces of shell, husk, and small stones), defects, mould and decays. The combination of these parameters, in terms of relative presence, represent a fundamental set of attributes conditioning dried fruits humans-senses-detectable-attributes (visual appearance, organolectic properties, etc.) and their overall quality in terms of marketable products. Sorting-selection strategies exist but sometimes they fail when a higher degree of detection is required especially if addressed to discriminate between dried fruits of relatively small dimensions and when aiming to perform an "early detection" of pathogen agents responsible of future moulds and decays development. Surface characteristics of dried fruits can be investigated by hyperspectral imaging (HSI). In this paper, specific and "ad hoc" applications addressed to propose quality detection logics, adopting a hyperspectral imaging (HSI) based approach, are described, compared and critically evaluated. Reflectance spectra of selected dried fruits (hazelnuts) of different quality and characterized by the presence of different contaminants and defects have been acquired by a laboratory device equipped with two HSI systems working in two different spectral ranges: visible-near infrared field (400-1000 nm) and near infrared field (1000-1700 nm). The spectra have been processed and results evaluated adopting both a simple and fast wavelength band ratio approach and a more sophisticated classification logic based on principal component (PCA) analysis.

  14. Retinal image quality in the rodent eye.

    PubMed

    Artal, P; Herreros de Tejada, P; Muñoz Tedó, C; Green, D G

    1998-01-01

    Many rodents do not see well. For a target to be resolved by a rat or a mouse, it must subtend a visual angle of a degree or more. It is commonly assumed that this poor spatial resolving capacity is due to neural rather than optical limitations, but the quality of the retinal image has not been well characterized in these animals. We have modified a double-pass apparatus, initially designed for the human eye, so it could be used with rodents to measure the modulation transfer function (MTF) of the eye's optics. That is, the double-pass retinal image of a monochromatic (lambda = 632.8 nm) point source was digitized with a CCD camera. From these double-pass measurements, the single-pass MTF was computed under a variety of conditions of focus and with different pupil sizes. Even with the eye in best focus, the image quality in both rats and mice is exceedingly poor. With a 1-mm pupil, for example, the MTF in the rat had an upper limit of about 2.5 cycles/deg, rather than the 28 cycles/deg one would obtain if the eye were a diffraction-limited system. These images are about 10 times worse than the comparable retinal images in the human eye. Using our measurements of the optics and the published behavioral and electrophysiological contrast sensitivity functions (CSFs) of rats, we have calculated the CSF that the rat would have if it had perfect rather than poor optics. We find, interestingly, that diffraction-limited optics would produce only slight improvement overall. That is, in spite of retinal images which are of very low quality, the upper limit of visual resolution in rodents is neurally determined. Rats and mice seem to have eyes in which the optics and retina/brain are well matched. PMID:9682864

  15. Image quality assessment and human visual system

    NASA Astrophysics Data System (ADS)

    Gao, Xinbo; Lu, Wen; Tao, Dacheng; Li, Xuelong

    2010-07-01

    This paper summaries the state-of-the-art of image quality assessment (IQA) and human visual system (HVS). IQA provides an objective index or real value to measure the quality of the specified image. Since human beings are the ultimate receivers of visual information in practical applications, the most reliable IQA is to build a computational model to mimic the HVS. According to the properties and cognitive mechanism of the HVS, the available HVS-based IQA methods can be divided into two categories, i.e., bionics methods and engineering methods. This paper briefly introduces the basic theories and development histories of the above two kinds of HVS-based IQA methods. Finally, some promising research issues are pointed out in the end of the paper.

  16. Data-Driven Affective Filtering for Images and Videos.

    PubMed

    Li, Teng; Ni, Bingbing; Xu, Mengdi; Wang, Meng; Gao, Qingwei; Yan, Shuicheng

    2015-10-01

    In this paper, a novel system is developed for synthesizing user-specified emotions onto arbitrary input images or videos. Other than defining the visual affective model based on empirical knowledge, a data-driven learning framework is proposed to extract the emotion-related knowledge from a set of emotion-annotated images. In a divide-and-conquer manner, the images are clustered into several emotion-specific scene subgroups for model learning. The visual affection is modeled with Gaussian mixture models based on color features of local image patches. For the purpose of affective filtering, the feature distribution of the target is aligned to the statistical model constructed from the emotion-specific scene subgroup, through a piecewise linear transformation. The transformation is derived through a learning algorithm, which is developed with the incorporation of a regularization term enforcing spatial smoothness, edge preservation, and temporal smoothness for the derived image or video transformation. Optimization of the objective function is sought via standard nonlinear method. Intensive experimental results and user studies demonstrate that the proposed affective filtering framework can yield effective and natural effects for images and videos. PMID:25675469

  17. Metal artifact reduction and image quality evaluation of lumbar spine CT images using metal sinogram segmentation.

    PubMed

    Kaewlek, Titipong; Koolpiruck, Diew; Thongvigitmanee, Saowapak; Mongkolsuk, Manus; Thammakittiphan, Sastrawut; Tritrakarn, Siri-on; Chiewvit, Pipat

    2015-01-01

    Metal artifacts often appear in the images of computed tomography (CT) imaging. In the case of lumbar spine CT images, artifacts disturb the images of critical organs. These artifacts can affect the diagnosis, treatment, and follow up care of the patient. One approach to metal artifact reduction is the sinogram completion method. A mixed-variable thresholding (MixVT) technique to identify the suitable metal sinogram is proposed. This technique consists of four steps: 1) identify the metal objects in the image by using k-mean clustering with the soft cluster assignment, 2) transform the image by separating it into two sinograms, one of which is the sinogram of the metal object, with the surrounding tissue shown in the second sinogram. The boundary of the metal sinogram is then found by the MixVT technique, 3) estimate the new value of the missing data in the metal sinogram by linear interpolation from the surrounding tissue sinogram, 4) reconstruct a modified sinogram by using filtered back-projection and complete the image by adding back the image of the metal object into the reconstructed image to form the complete image. The quantitative and clinical image quality evaluation of our proposed technique demonstrated a significant improvement in image clarity and detail, which enhances the effectiveness of diagnosis and treatment. PMID:26756404

  18. Optimization of exposure in panoramic radiography while maintaining image quality using adaptive filtering.

    PubMed

    Svenson, Björn; Larsson, Lars; Båth, Magnus

    2016-01-01

    Objective The purpose of the present study was to investigate the potential of using advanced external adaptive image processing for maintaining image quality while reducing exposure in dental panoramic storage phosphor plate (SPP) radiography. Materials and methods Thirty-seven SPP radiographs of a skull phantom were acquired using a Scanora panoramic X-ray machine with various tube load, tube voltage, SPP sensitivity and filtration settings. The radiographs were processed using General Operator Processor (GOP) technology. Fifteen dentists, all within the dental radiology field, compared the structural image quality of each radiograph with a reference image on a 5-point rating scale in a visual grading characteristics (VGC) study. The reference image was acquired with the acquisition parameters commonly used in daily operation (70 kVp, 150 mAs and sensitivity class 200) and processed using the standard process parameters supplied by the modality vendor. Results All GOP-processed images with similar (or higher) dose as the reference image resulted in higher image quality than the reference. All GOP-processed images with similar image quality as the reference image were acquired at a lower dose than the reference. This indicates that the external image processing improved the image quality compared with the standard processing. Regarding acquisition parameters, no strong dependency of the image quality on the radiation quality was seen and the image quality was mainly affected by the dose. Conclusions The present study indicates that advanced external adaptive image processing may be beneficial in panoramic radiography for increasing the image quality of SPP radiographs or for reducing the exposure while maintaining image quality. PMID:26478956

  19. Resource quality affects carbon cycling in deep-sea sediments.

    PubMed

    Mayor, Daniel J; Thornton, Barry; Hay, Steve; Zuur, Alain F; Nicol, Graeme W; McWilliam, Jenna M; Witte, Ursula F M

    2012-09-01

    Deep-sea sediments cover ~70% of Earth's surface and represent the largest interface between the biological and geological cycles of carbon. Diatoms and zooplankton faecal pellets naturally transport organic material from the upper ocean down to the deep seabed, but how these qualitatively different substrates affect the fate of carbon in this permanently cold environment remains unknown. We added equal quantities of (13)C-labelled diatoms and faecal pellets to a cold water (-0.7 °C) sediment community retrieved from 1080 m in the Faroe-Shetland Channel, Northeast Atlantic, and quantified carbon mineralization and uptake by the resident bacteria and macrofauna over a 6-day period. High-quality, diatom-derived carbon was mineralized >300% faster than that from low-quality faecal pellets, demonstrating that qualitative differences in organic matter drive major changes in the residence time of carbon at the deep seabed. Benthic bacteria dominated biological carbon processing in our experiments, yet showed no evidence of resource quality-limited growth; they displayed lower growth efficiencies when respiring diatoms. These effects were consistent in contrasting months. We contend that respiration and growth in the resident sediment microbial communities were substrate and temperature limited, respectively. Our study has important implications for how future changes in the biochemical makeup of exported organic matter will affect the balance between mineralization and sequestration of organic carbon in the largest ecosystem on Earth. PMID:22378534

  20. Retinal image quality, reading and myopia.

    PubMed

    Collins, Michael J; Buehren, Tobias; Iskander, D Robert

    2006-01-01

    Analysis was undertaken of the retinal image characteristics of the best-spectacle corrected eyes of progressing myopes (n = 20, mean age = 22 years; mean spherical equivalent = -3.84 D) and a control group of emmetropes (n = 20, mean age = 23 years; mean spherical equivalent = 0.00 D) before and after a 2h reading task. Retinal image quality was calculated based upon wavefront measurements taken with a Hartmann-Shack sensor with fixation on both a far (5.5 m) and near (individual reading distance) target. The visual Strehl ratio based on the optical transfer function (VSOTF) was significantly worse for the myopes prior to reading for both the far (p = 0.01) and near (p = 0.03) conditions. The myopic group showed significant reductions in various aspects of retinal image quality compared with the emmetropes, involving components of the modulation transfer function, phase transfer function and point spread function, often along the vertical meridian of the eye. The depth of focus of the myopes (0.54 D) was larger (p = 0.02) than the emmetropes (0.42 D) and the distribution of refractive power (away from optimal sphero-cylinder) was greater in the myopic eyes (variance of distributions p < 0.05). We found evidence that the lead and lag of accommodation are influenced by the higher order aberrations of the eye (e.g. significant correlations between lead/lag and the peak of the visual Strehl ratio based on the MTF). This could indicate that the higher accommodation lags seen in myopes are providing optimized retinal image characteristics. The interaction between low and high order aberrations of the eye play a significant role in reducing the retinal image quality of myopic eyes compared with emmetropes. PMID:15913701

  1. Towards real-time image quality assessment

    NASA Astrophysics Data System (ADS)

    Geary, Bobby; Grecos, Christos

    2011-03-01

    We introduce a real-time implementation and evaluation of a new fast accurate full reference based image quality metric. The popular general image quality metric known as the Structural Similarity Index Metric (SSIM) has been shown to be an effective, efficient and useful, finding many practical and theoretical applications. Recently the authors have proposed an enhanced version of the SSIM algorithm known as the Rotated Gaussian Discrimination Metric (RGDM). This approach uses a Gaussian-like discrimination function to evaluate local contrast and luminance. RGDM was inspired by an exploration of local statistical parameter variations in relation to variation of Mean Opinion Score (MOS) for a range of particular distortion types. In this paper we out-line the salient features of the derivation of RGDM and show how analyses of local statistics of distortion type necessitate variation in discrimination function width. Results on the LIVE image database show tight banding of RGDM metric value when plotted against mean opinion score indicating the usefulness of this metric. We then explore a number of strategies for algorithmic speed-up including the application of Integral Images for patch based computation optimisation, cost reduction for the evaluation of the discrimination function and general loop unrolling. We also employ fast Single Instruction Multiple Data (SIMD) intrinsics and explore data parallel decomposition on a multi-core Intel Processor.

  2. Rotation of Boar Semen Doses During Storage Affects Sperm Quality.

    PubMed

    Schulze, M; Rüdiger, K; Waberski, D

    2015-08-01

    It is common practice to rotate boar semen doses during storage for prevention of sperm sedimentation. In this study, the effect of rotation of boar semen doses during storage on sperm quality was investigated. Manual turning twice daily and automatic rotation five times per hour resulted in the following effects: alkalinization of the BTS-extender, loss of membrane integrity at day 3, and loss of motility and changes in sperm kinematics during a thermoresistance test at day 5. Using a pH-stabilized variant of BTS extender, sperm motility and velocity decreased in continuously rotated samples, whereas membrane integrity and mitochondrial activity remain unaffected. It is concluded that rotation of semen samples adversely affects sperm quality and, therefore, should no longer be recommended for AI practice. PMID:25974759

  3. Subjective quality of life in war-affected populations

    PubMed Central

    2013-01-01

    Background Exposure to traumatic war events may lead to a reduction in quality of life for many years. Research suggests that these impairments may be associated with posttraumatic stress symptoms; however, wars also have a profound impact on social conditions. Systematic studies utilising subjective quality of life (SQOL) measures are particularly rare and research in post-conflict settings is scarce. Whether social factors independently affect SQOL after war in addition to symptoms has not been explored in large scale studies. Method War-affected community samples were recruited through a random-walk technique in five Balkan countries and through registers and networking in three Western European countries. The interviews were carried out on average 8 years after the war in the Balkans. SQOL was assessed on Manchester Short Assessment of Quality of Life - MANSA. We explored the impact of war events, posttraumatic stress symptoms and post-war environment on SQOL. Results We interviewed 3313 Balkan residents and 854 refugees in Western Europe. The MANSA mean score was 4.8 (SD = 0.9) for the Balkan sample and 4.7 (SD = 0.9) for refugees. In both samples participants were explicitly dissatisfied with their employment and financial situation. Posttraumatic stress symptoms had a strong negative impact on SQOL. Traumatic war events were directly linked with lower SQOL in Balkan residents. The post-war environment influenced SQOL in both groups: unemployment was associated with lower SQOL and recent contacts with friends with higher SQOL. Experiencing more migration-related stressors was linked to poorer SQOL in refugees. Conclusion Both posttraumatic stress symptoms and aspects of the post-war environment independently influence SQOL in war-affected populations. Aid programmes to improve wellbeing following the traumatic war events should include both treatment of posttraumatic symptoms and social interventions. PMID:23819629

  4. Image quality vs. sensitivity: fundamental sensor system engineering

    NASA Astrophysics Data System (ADS)

    Schueler, Carl F.

    2008-08-01

    This paper focuses on the fundamental system engineering tradeoff driving almost all remote sensing design efforts, affecting complexity, cost, performance, schedule, and risk: image quality vs. sensitivity. This single trade encompasses every aspect of performance, including radiometric accuracy, dynamic range and precision, as well as spatial, spectral, and temporal coverage and resolution. This single trade also encompasses every aspect of design, including mass, dimensions, power, orbit selection, spacecraft interface, sensor and spacecraft functional trades, pointing or scanning architecture, sensor architecture (e.g., field-of-view, optical form, aperture, f/#, material properties), electronics, mechanical and thermal properties. The relationship between image quality and sensitivity is introduced based on the concepts of modulation transfer function (MTF) and signal-to-noise ratio (SNR) with examples to illustrate the balance to be achieved by the system architect to optimize cost, complexity, performance and risk relative to end-user requirements.

  5. Factors affecting quality of dried low-rank coals

    SciTech Connect

    Karthikeyan, M.; Kuma, J.V.M.; Hoe, C.S.; Ngo, D.L.Y.

    2007-07-01

    The chemical and physical properties of coal are strongly affected by the upgrading process employed. For high-moisture coals, upgrading involves thermal dehydration to improve the calorific value of the coal on mass basis. This study evaluates the feasibility of upgrading a low-rank/grade coal using the oven drying method. The objective of this research work is to study the drying characteristics of low-rank coals and to understand the factors affecting the quality of dried low-rank coals. This article describes laboratory experiments conducted on the characterization of the low-rank coals before and after the drying process. The results on drying kinetics, re-absorption of coal samples, and proximate analysis of coal samples before and after drying are discussed. It was found that the upgrading process produced coal with better heating value and combustion characteristics than those of the raw coal samples.

  6. Improving Secondary Ion Mass Spectrometry Image Quality with Image Fusion

    PubMed Central

    Tarolli, Jay G.; Jackson, Lauren M.; Winograd, Nicholas

    2014-01-01

    The spatial resolution of chemical images acquired with cluster secondary ion mass spectrometry (SIMS) is limited not only by the size of the probe utilized to create the images, but also by detection sensitivity. As the probe size is reduced to below 1 µm, for example, a low signal in each pixel limits lateral resolution due to counting statistics considerations. Although it can be useful to implement numerical methods to mitigate this problem, here we investigate the use of image fusion to combine information from scanning electron microscope (SEM) data with chemically resolved SIMS images. The advantage of this approach is that the higher intensity and, hence, spatial resolution of the electron images can help to improve the quality of the SIMS images without sacrificing chemical specificity. Using a pan-sharpening algorithm, the method is illustrated using synthetic data, experimental data acquired from a metallic grid sample, and experimental data acquired from a lawn of algae cells. The results show that up to an order of magnitude increase in spatial resolution is possible to achieve. A cross-correlation metric is utilized for evaluating the reliability of the procedure. PMID:24912432

  7. Diagnostic Imaging of Canine Hepatobiliary Affections: A Review

    PubMed Central

    Kumar, Vijay; Kumar, Adarsh; Varshney, A. C.; Tyagi, S. P.; Kanwar, M. S.; Sharma, S. K.

    2012-01-01

    Hepatic disease is often treatable and has a predictable prognosis when a definitive diagnosis is made. The aim of clinicopathological evaluation of hepatobiliary affections is to identify and characterize hepatic damage and dysfunction, identify possible primary causes of secondary liver disease, differentiate causes of icterus, evaluate potential anaesthetic risks, assess prognosis and response to xenobiotics, and monitor response to therapy. This paper describes the different diagnostic methods and imaging techniques employed in diagnosis of hepatobiliary affections in dogs. Besides reviewing the significant clinical manifestations and imaging structural abnormalities in diagnostic approach to different hepatic affections, it also depicts radiographic, ultrasonographic, and wherever applicable, the laparoscopic characterization of different hepatic affections and target lesions encountered in clinical cases presented in the Teaching Veterinary Clinical Complex, COVAS, Palampur in the year 2007-2008. PMID:22577609

  8. Model-based quantification of image quality

    NASA Technical Reports Server (NTRS)

    Hazra, Rajeeb; Miller, Keith W.; Park, Stephen K.

    1989-01-01

    In 1982, Park and Schowengerdt published an end-to-end analysis of a digital imaging system quantifying three principal degradation components: (1) image blur - blurring caused by the acquisition system, (2) aliasing - caused by insufficient sampling, and (3) reconstruction blur - blurring caused by the imperfect interpolative reconstruction. This analysis, which measures degradation as the square of the radiometric error, includes the sample-scene phase as an explicit random parameter and characterizes the image degradation caused by imperfect acquisition and reconstruction together with the effects of undersampling and random sample-scene phases. In a recent paper Mitchell and Netravelli displayed the visual effects of the above mentioned degradations and presented subjective analysis about their relative importance in determining image quality. The primary aim of the research is to use the analysis of Park and Schowengerdt to correlate their mathematical criteria for measuring image degradations with subjective visual criteria. Insight gained from this research can be exploited in the end-to-end design of optical systems, so that system parameters (transfer functions of the acquisition and display systems) can be designed relative to each other, to obtain the best possible results using quantitative measurements.

  9. Influence of slice overlap on positron emission tomography image quality

    NASA Astrophysics Data System (ADS)

    McKeown, Clare; Gillen, Gerry; Dempsey, Mary Frances; Findlay, Caroline

    2016-02-01

    PET scans use overlapping acquisition beds to correct for reduced sensitivity at bed edges. The optimum overlap size for the General Electric (GE) Discovery 690 has not been established. This study assesses how image quality is affected by slice overlap. Efficacy of 23% overlaps (recommended by GE) and 49% overlaps (maximum possible overlap) were specifically assessed. European Association of Nuclear Medicine (EANM) guidelines for calculating minimum injected activities based on overlap size were also reviewed. A uniform flood phantom was used to assess noise (coefficient of variation, (COV)) and voxel accuracy (activity concentrations, Bq ml-1). A NEMA (National Electrical Manufacturers Association) body phantom with hot/cold spheres in a background activity was used to assess contrast recovery coefficients (CRCs) and signal to noise ratios (SNR). Different overlap sizes and sphere-to-background ratios were assessed. COVs for 49% and 23% overlaps were 9% and 13% respectively. This increased noise was difficult to visualise on the 23% overlap images. Mean voxel activity concentrations were not affected by overlap size. No clinically significant differences in CRCs were observed. However, visibility and SNR of small, low contrast spheres (⩽13 mm diameter, 2:1 sphere to background ratio) may be affected by overlap size in low count studies if they are located in the overlap area. There was minimal detectable influence on image quality in terms of noise, mean activity concentrations or mean CRCs when comparing 23% overlap with 49% overlap. Detectability of small, low contrast lesions may be affected in low count studies—however, this is a worst-case scenario. The marginal benefits of increasing overlap from 23% to 49% are likely to be offset by increased patient scan times. A 23% overlap is therefore appropriate for clinical use. An amendment to EANM guidelines for calculating injected activities is also proposed which better reflects the effect overlap size has

  10. Optimizing 3D image quality and performance for stereoscopic gaming

    NASA Astrophysics Data System (ADS)

    Flack, Julien; Sanderson, Hugh; Pegg, Steven; Kwok, Simon; Paterson, Daniel

    2009-02-01

    The successful introduction of stereoscopic TV systems, such as Samsung's 3D Ready Plasma, requires high quality 3D content to be commercially available to the consumer. Console and PC games provide the most readily accessible source of high quality 3D content. This paper describes innovative developments in a generic, PC-based game driver architecture that addresses the two key issues affecting 3D gaming: quality and speed. At the heart of the quality issue are the same considerations that studios face producing stereoscopic renders from CG movies: how best to perform the mapping from a geometric CG environment into the stereoscopic display volume. The major difference being that for game drivers this mapping cannot be choreographed by hand but must be automatically calculated in real-time without significant impact on performance. Performance is a critical issue when dealing with gaming. Stereoscopic gaming has traditionally meant rendering the scene twice with the associated performance overhead. An alternative approach is to render the scene from one virtual camera position and use information from the z-buffer to generate a stereo pair using Depth-Image-Based Rendering (DIBR). We analyze this trade-off in more detail and provide some results relating to both 3D image quality and render performance.

  11. The mobile image quality survey game

    NASA Astrophysics Data System (ADS)

    Rasmussen, D. René

    2012-01-01

    In this paper we discuss human assessment of the quality of photographic still images, that are degraded in various manners relative to an original, for example due to compression or noise. In particular, we examine and present results from a technique where observers view images on a mobile device, perform pairwise comparisons, identify defects in the images, and interact with the display to indicate the location of the defects. The technique measures the response time and accuracy of the responses. By posing the survey in a form similar to a game, providing performance feedback to the observer, the technique attempts to increase the engagement of the observers, and to avoid exhausting observers, a factor that is often a problem for subjective surveys. The results are compared with the known physical magnitudes of the defects and with results from similar web-based surveys. The strengths and weaknesses of the technique are discussed. Possible extensions of the technique to video quality assessment are also discussed.

  12. Hyperspectral and multispectral imaging for evaluating food safety and quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Spectral imaging technologies have been developed rapidly during the past decade. This paper presents hyperspectral and multispectral imaging technologies in the area of food safety and quality evaluation, with an introduction, demonstration, and summarization of the spectral imaging techniques avai...

  13. Influential sources affecting Bangkok adolescent body image perceptions.

    PubMed

    Thianthai, Chulanee

    2006-01-01

    The study of body image-related problems in non-Western countries is still very limited. Thus, this study aims to identify the main influential sources and show how they affect the body image perceptions of Bangkok adolescents. The researcher recruited 400 Thai male and female adolescents in Bangkok, attending high school to freshmen level, ranging from 16-19 years, to participate in this study. Survey questionnaires were distributed to every student and follow-up interviews conducted with 40 students. The findings showed that there are eight main influential sources respectively ranked from the most influential to the least influential: magazines, television, peer group, familial, fashion trend, the opposite gender, self-realization and health knowledge. Similar to those studies conducted in Western countries, more than half of the total percentage was the influence of mass media and peer groups. Bangkok adolescents also internalized Western ideal beauty through these mass media channels. Alike studies conducted in the West, there was similarities in the process of how these influential sources affect Bangkok adolescent body image perception, with the exception of familial source. In conclusion, taking the approach of identifying the main influential sources and understanding how they affect adolescent body image perceptions can help prevent adolescents from having unhealthy views and taking risky measures toward their bodies. More studies conducted in non-Western countries are needed in order to build a cultural sensitive program, catered to the body image problems occurring in adolescents within that particular society. PMID:17340854

  14. On pictures and stuff: image quality and material appearance

    NASA Astrophysics Data System (ADS)

    Ferwerda, James A.

    2014-02-01

    Realistic images are a puzzle because they serve as visual representations of objects while also being objects themselves. When we look at an image we are able to perceive both the properties of the image and the properties of the objects represented by the image. Research on image quality has typically focused improving image properties (resolution, dynamic range, frame rate, etc.) while ignoring the issue of whether images are serving their role as visual representations. In this paper we describe a series of experiments that investigate how well images of different quality convey information about the properties of the objects they represent. In the experiments we focus on the effects that two image properties (contrast and sharpness) have on the ability of images to represent the gloss of depicted objects. We found that different experimental methods produced differing results. Specifically, when the stimulus images were presented using simultaneous pair comparison, observers were influenced by the surface properties of the images and conflated changes in image contrast and sharpness with changes in object gloss. On the other hand, when the stimulus images were presented sequentially, observers were able to disregard the image plane properties and more accurately match the gloss of the objects represented by the different quality images. These findings suggest that in understanding image quality it is useful to distinguish between quality of the imaging medium and the quality of the visual information represented by that medium.

  15. Image analysis for dental bone quality assessment using CBCT imaging

    NASA Astrophysics Data System (ADS)

    Suprijanto; Epsilawati, L.; Hajarini, M. S.; Juliastuti, E.; Susanti, H.

    2016-03-01

    Cone beam computerized tomography (CBCT) is one of X-ray imaging modalities that are applied in dentistry. Its modality can visualize the oral region in 3D and in a high resolution. CBCT jaw image has potential information for the assessment of bone quality that often used for pre-operative implant planning. We propose comparison method based on normalized histogram (NH) on the region of inter-dental septum and premolar teeth. Furthermore, the NH characteristic from normal and abnormal bone condition are compared and analyzed. Four test parameters are proposed, i.e. the difference between teeth and bone average intensity (s), the ratio between bone and teeth average intensity (n) of NH, the difference between teeth and bone peak value (Δp) of NH, and the ratio between teeth and bone of NH range (r). The results showed that n, s, and Δp have potential to be the classification parameters of dental calcium density.

  16. Stereoscopic image quality assessment using disparity-compensated view filtering

    NASA Astrophysics Data System (ADS)

    Song, Yang; Yu, Mei; Jiang, Gangyi; Shao, Feng; Peng, Zongju

    2016-03-01

    Stereoscopic image quality assessment (IQA) plays a vital role in stereoscopic image/video processing systems. We propose a new quality assessment for stereoscopic image that uses disparity-compensated view filtering (DCVF). First, because a stereoscopic image is composed of different frequency components, DCVF is designed to decompose it into high-pass and low-pass components. Then, the qualities of different frequency components are acquired according to their phase congruency and coefficient distribution characteristics. Finally, support vector regression is utilized to establish a mapping model between the component qualities and subjective qualities, and stereoscopic image quality is calculated using this mapping model. Experiments on the LIVE 3-D IQA database and NBU 3-D IQA databases demonstrate that the proposed method can evaluate stereoscopic image quality accurately. Compared with several state-of-the-art quality assessment methods, the proposed method is more consistent with human perception.

  17. Finger vein image quality evaluation using support vector machines

    NASA Astrophysics Data System (ADS)

    Yang, Lu; Yang, Gongping; Yin, Yilong; Xiao, Rongyang

    2013-02-01

    In an automatic finger-vein recognition system, finger-vein image quality is significant for segmentation, enhancement, and matching processes. In this paper, we propose a finger-vein image quality evaluation method using support vector machines (SVMs). We extract three features including the gradient, image contrast, and information capacity from the input image. An SVM model is built on the training images with annotated quality labels (i.e., high/low) and then applied to unseen images for quality evaluation. To resolve the class-imbalance problem in the training data, we perform oversampling for the minority class with random-synthetic minority oversampling technique. Cross-validation is also employed to verify the reliability and stability of the learned model. Our experimental results show the effectiveness of our method in evaluating the quality of finger-vein images, and by discarding low-quality images detected by our method, the overall finger-vein recognition performance is considerably improved.

  18. Multilevel factors affecting quality: examples from the cancer care continuum.

    PubMed

    Zapka, Jane; Taplin, Stephen H; Ganz, Patricia; Grunfeld, Eva; Sterba, Katherine

    2012-05-01

    The complex environmental context must be considered as we move forward to improve cancer care and, ultimately, patient and population outcomes. The cancer care continuum represents several care types, each of which includes multiple technical and communication steps and interfaces among patients, providers, and organizations. We use two case scenarios to 1) illustrate the variability, diversity, and interaction of factors from multiple levels that affect care quality and 2) discuss research implications and provide hypothetical examples of multilevel interventions. Each scenario includes a targeted literature review to illustrate contextual influences upon care and sets the stage for theory-informed interventions. The screening case highlights access issues in older women, and the survivorship case illustrates the multiple transition challenges faced by patients, families, and organizations. Example interventions show the potential gains of implementing intervention strategies that work synergistically at multiple levels. While research examining multilevel intervention is a priority, it presents numerous study design, measurement, and analytic challenges. PMID:22623591

  19. Application of ultrasound processed images in space: assessing diffuse affectations

    NASA Astrophysics Data System (ADS)

    Pérez-Poch, A.; Bru, C.; Nicolau, C.

    The purpose of this study was to evaluate diffuse affectations in the liver using texture image processing techniques. Ultrasound diagnose equipments are the election of choice to be used in space environments as they are free from hazardous effects on health. However, due to the need for highly trained radiologists to assess the images, this imaging method is mainly applied on focal lesions rather than on non-focal ones. We have conducted a clinical study on 72 patients with different degrees of chronic hepatopaties and a group of control of 18 individuals. All subjects' clinical reports and results of biopsies were compared to the degree of affectation calculated by our computer system , thus validating the method. Full statistical results are given in the present paper showing a good correlation (r=0.61) between pathologist's report and analysis of the heterogenicity of the processed images from the liver. This computer system to analyze diffuse affectations may be used in-situ or via telemedicine to the ground.

  20. Image quality metrics for optical coherence angiography.

    PubMed

    Lozzi, Andrea; Agrawal, Anant; Boretsky, Adam; Welle, Cristin G; Hammer, Daniel X

    2015-07-01

    We characterized image quality in optical coherence angiography (OCA) en face planes of mouse cortical capillary network in terms of signal-to-noise ratio (SNR) and Weber contrast (Wc) through a novel mask-based segmentation method. The method was used to compare two adjacent B-scan processing algorithms, (1) average absolute difference (AAD) and (2) standard deviation (SD), while varying the number of lateral cross-sections acquired (also known as the gate length, N). AAD and SD are identical at N = 2 and exhibited similar image quality for N<10. However, AAD is relatively less susceptible to bulk tissue motion artifact than SD. SNR and Wc were 15% and 35% higher for AAD from N = 25 to 100. In addition data sets were acquired with two objective lenses with different magnifications to quantify the effect of lateral resolution on fine capillary detection. The lower power objective yielded a significant mean broadening of 17% in Full Width Half Maximum (FWHM) diameter. These results may guide study and device designs for OCA capillary and blood flow quantification. PMID:26203372

  1. Mechanisms affecting water quality in an intermittent piped water supply.

    PubMed

    Kumpel, Emily; Nelson, Kara L

    2014-01-01

    Drinking water distribution systems throughout the world supply water intermittently, leaving pipes without pressure between supply cycles. Understanding the multiple mechanisms that affect contamination in these intermittent water supplies (IWS) can be used to develop strategies to improve water quality. To study these effects, we tested water quality in an IWS system with infrequent and short water delivery periods in Hubli-Dharwad, India. We continuously measured pressure and physicochemical parameters and periodically collected grab samples to test for total coliform and E. coli throughout supply cycles at 11 sites. When the supply was first turned on, water with elevated turbidity and high concentrations of indicator bacteria was flushed out of pipes. At low pressures (<10 psi), elevated indicator bacteria were frequently detected even when there was a chlorine residual, suggesting persistent contamination had occurred through intrusion or backflow. At pressures between 10 and 17 psi, evidence of periodic contamination suggested that transient intrusion, backflow, release of particulates, or sloughing of biofilms from pipe walls had occurred. Few total coliform and no E. coli were detected when water was delivered with a chlorine residual and at pressures >17 psi. PMID:24459990

  2. Parameters affecting greywater quality and its safety for reuse.

    PubMed

    Maimon, Adi; Friedler, Eran; Gross, Amit

    2014-07-15

    Reusing greywater (GW) for on-site irrigation is becoming a common practice worldwide. Alongside its benefits, GW reuse might pose health and environmental risks. The current study assesses the risks associated with on-site GW reuse and the main factors affecting them. GW from 34 households in Israel was analyzed for physicochemical parameters, Escherichia coli (as an indicator for rotavirus), Pseudomonas aeruginosa and Staphylococcus aureus. Each participating household filled out a questionnaire about their GW sources, treatment and usages. Quantitative microbial risk assessment (QMRA) was performed based on the measured microbial quality, and on exposure scenarios derived from the questionnaires and literature data. The type of treatment was found to have a significant effect on the quality of the treated GW. The average E. coli counts in GW (which exclude kitchen effluent) treated by professionally-designed system resulted in acceptable risk under all exposure scenarios while the risk from inadequately-treated GW was above the accepted level as set by the WHO. In conclusion, safe GW reuse requires a suitable and well-designed treatment system. A risk-assessment approach should be used to adjust the current regulations/guidelines and to assess the performance of GW treatment and reuse systems. PMID:24751591

  3. Contemporary Quality of Life Issues Affecting Gynecologic Cancer Survivors

    PubMed Central

    Carter, Jeanne; Penson, Richard; Barakat, Richard; Wenzel, Lari

    2015-01-01

    Gynecologic cancers account for approximately 11% of the newly diagnosed cancers in women in the United States and 18% in the world.1 The most common gynecologic malignancies occur in the uterus and endometrium (53%), ovary (25%), and cervix (14%).2 Cervical cancer is most prevalent in premenopausal women, during their childbearing years, whereas uterine and ovarian cancers tend to present in the perimenopausal or menopausal period. Vaginal and vulvar cancers and malignancies arising from gestation, or gestational trophoblastic neoplasms, occur to a lesser extent. Regardless of cancer origin or age of onset, the disease and its treatment can produce short- and long-term sequelae (ie, sexual dysfunction, infertility, or lymphedema) that adversely affect quality of life (QOL). This article outlines the primary contemporary issues or concerns that may affect QOL and offers strategies to offset or mitigate QOL disruption. These contemporary issues are identified within the domains of sexual functioning, reproductive issues, lymphedema, and the contribution of health-related QOL (HRQOL) in influential gynecologic cancer clinical trials. PMID:22244668

  4. Quality Control of Diffusion Weighted Images

    PubMed Central

    Liu, Zhexing; Wang, Yi; Gerig, Guido; Gouttard, Sylvain; Tao, Ran; Fletcher, Thomas; Styner, Martin

    2013-01-01

    Diffusion Tensor Imaging (DTI) has become an important MRI procedure to investigate the integrity of white matter in brain in vivo. DTI is estimated from a series of acquired Diffusion Weighted Imaging (DWI) volumes. DWI data suffers from inherent low SNR, overall long scanning time of multiple directional encoding with correspondingly large risk to encounter several kinds of artifacts. These artifacts can be too severe for a correct and stable estimation of the diffusion tensor. Thus, a quality control (QC) procedure is absolutely necessary for DTI studies. Currently, routine DTI QC procedures are conducted manually by visually checking the DWI data set in a gradient by gradient and slice by slice way. The results often suffer from low consistence across different data sets, lack of agreement of different experts, and difficulty to judge motion artifacts by qualitative inspection. Additionally considerable manpower is needed for this step due to the large number of images to QC, which is common for group comparison and longitudinal studies, especially with increasing number of diffusion gradient directions. We present a framework for automatic DWI QC. We developed a tool called DTIPrep which pipelines the QC steps with a detailed protocoling and reporting facility. And it is fully open source. This framework/tool has been successfully applied to several DTI studies with several hundred DWIs in our lab as well as collaborating labs in Utah and Iowa. In our studies, the tool provides a crucial piece for robust DTI analysis in brain white matter study. PMID:24353379

  5. Clinical factors affecting quality of life of patients with asthma

    PubMed Central

    Uchmanowicz, Bartosz; Panaszek, Bernard; Uchmanowicz, Izabella; Rosińczuk, Joanna

    2016-01-01

    Background In recent years, there has been increased interest in the subjective quality of life (QoL) of patients with bronchial asthma. QoL is a significant indicator guiding the efforts of professionals caring for patients, especially chronically ill ones. The identification of factors affecting the QoL reported by patients, despite their existing condition, is important and useful to provide multidisciplinary care for these patients. Aim To investigate the clinical factors affecting asthma patients’ QoL. Methods The study comprised 100 patients (73 female, 27 male) aged 18–84 years (mean age was 45.7) treated in the Allergy Clinic of the Wroclaw Medical University Department and Clinic of Internal Diseases, Geriatrics and Allergology. All asthma patients meeting the inclusion criteria were invited to participate. Data on sociodemographic and clinical variables were collected. In this study, we used medical record analysis and two questionnaires: the Asthma Quality of Life Questionnaire (AQLQ) to assess the QoL of patients with asthma and the Asthma Control Test to measure asthma control. Results Active smokers were shown to have a significantly lower QoL in the “Symptoms” domain than nonsmokers (P=0.006). QoL was also demonstrated to decrease significantly as the frequency of asthma exacerbations increased (R=−0.231, P=0.022). QoL in the domain “Activity limitation” was shown to increase significantly along with the number of years of smoking (R=0.404; P=0.004). Time from onset and the dominant symptom of asthma significantly negatively affected QoL in the “Activity limitation” domain of the AQLQ (R=−0.316, P=0.001; P=0.029, respectively). QoL scores in the “Emotional function” and “Environmental stimuli” subscale of the AQLQ decreased significantly as time from onset increased (R=−0.200, P=0.046; R=−0.328, P=0.001, respectively). Conclusion Patients exhibiting better symptom control have higher QoL scores. Asthma patients’ Qo

  6. The experimentation research of IR imaging system capability affected by sapphire window's pneumatic calefaction

    NASA Astrophysics Data System (ADS)

    Liu, Yang-peng; Pan, Guo-qing; Zhang, Yun-qiang

    2009-07-01

    In the inclement pneumatic calefaction condition, the window of IR imaging system will be calefied and emit infrared radiation, so that the Signal-to-Noise and quality of target IR image are felled off that are from the imaging system. At this rate the physical characteristic of IR window direct affect capability of imaging system controlled and guided homing by IR tracker and measure precision of target IR characteristics. The properties of sapphire make it an ideal choice for the high speed missile applications compared to other existing or emerging materials. But the research has not been reported about the infrared radiation characteristic of sapphire as the IR window. In this paper, based on an IR imaging system using the sapphire window, the experimentation and conclusions of IR thermal image measurement affected by IR window's pneumatic calefaction have been accomplished. Firstly, the temperatures of sapphire window at supersonic flight extended over 1 km and 15 km from the ground have been estimated by calculating the flow and state variables and the aerodynamic heating into the window. On the base of the results calculated the window static state calefaction experimentation and electric arc wind tunnel experimentation had been designed and completed to validate the effect degree of pneumatic calefaction to the imaging system. With the temperatures of the sapphire window rising, in the image coming from the imaging system, the peak luminance of target image detected is increased, the background average luminance of the image is also increased, and the margin of above two varies in a little range. The data obtained from the different temperature experimentation have demonstrated that the IR flux due to the sapphire window becomes heated by friction with the air and heat transfer to the dome can obscure the target image created by the onboard IR sensor, depress Signal-to-Noise and resolving power of the imaging system, but can not overload the detector.

  7. Image Quality Characteristics of Handheld Display Devices for Medical Imaging

    PubMed Central

    Yamazaki, Asumi; Liu, Peter; Cheng, Wei-Chung; Badano, Aldo

    2013-01-01

    Handheld devices such as mobile phones and tablet computers have become widespread with thousands of available software applications. Recently, handhelds are being proposed as part of medical imaging solutions, especially in emergency medicine, where immediate consultation is required. However, handheld devices differ significantly from medical workstation displays in terms of display characteristics. Moreover, the characteristics vary significantly among device types. We investigate the image quality characteristics of various handheld devices with respect to luminance response, spatial resolution, spatial noise, and reflectance. We show that the luminance characteristics of the handheld displays are different from those of workstation displays complying with grayscale standard target response suggesting that luminance calibration might be needed. Our results also demonstrate that the spatial characteristics of handhelds can surpass those of medical workstation displays particularly for recent generation devices. While a 5 mega-pixel monochrome workstation display has horizontal and vertical modulation transfer factors of 0.52 and 0.47 at the Nyquist frequency, the handheld displays released after 2011 can have values higher than 0.63 at the respective Nyquist frequencies. The noise power spectra for workstation displays are higher than 1.2×10−5 mm2 at 1 mm−1, while handheld displays have values lower than 3.7×10−6 mm2. Reflectance measurements on some of the handheld displays are consistent with measurements for workstation displays with, in some cases, low specular and diffuse reflectance coefficients. The variability of the characterization results among devices due to the different technological features indicates that image quality varies greatly among handheld display devices. PMID:24236113

  8. Evaluation of scatter effects on image quality for breast tomosynthesis

    SciTech Connect

    Wu Gang; Mainprize, James G.; Boone, John M.; Yaffe, Martin J.

    2009-10-15

    Digital breast tomosynthesis uses a limited number (typically 10-20) of low-dose x-ray projections to produce a pseudo-three-dimensional volume tomographic reconstruction of the breast. The purpose of this investigation was to characterize and evaluate the effect of scattered radiation on the image quality for breast tomosynthesis. In a simulation, scatter point spread functions generated by a Monte Carlo simulation method were convolved over the breast projection to estimate the distribution of scatter for each angle of tomosynthesis projection. The results demonstrate that in the absence of scatter reduction techniques, images will be affected by cupping artifacts, and there will be reduced accuracy of attenuation values inferred from the reconstructed images. The effect of x-ray scatter on the contrast, noise, and lesion signal-difference-to-noise ratio (SDNR) in tomosynthesis reconstruction was measured as a function of the tumor size. When a with-scatter reconstruction was compared to one without scatter for a 5 cm compressed breast, the following results were observed. The contrast in the reconstructed central slice image of a tumorlike mass (14 mm in diameter) was reduced by 30%, the voxel value (inferred attenuation coefficient) was reduced by 28%, and the SDNR fell by 60%. The authors have quantified the degree to which scatter degrades the image quality over a wide range of parameters relevant to breast tomosynthesis, including x-ray beam energy, breast thickness, breast diameter, and breast composition. They also demonstrate, though, that even without a scatter rejection device, the contrast and SDNR in the reconstructed tomosynthesis slice are higher than those of conventional mammographic projection images acquired with a grid at an equivalent total exposure.

  9. Diffusion tensor imaging in Alzheimer's disease and affective disorders.

    PubMed

    Teipel, Stefan J; Walter, Martin; Likitjaroen, Yuttachai; Schönknecht, Peter; Gruber, Oliver

    2014-09-01

    The functional organization of the brain in segregated neuronal networks has become a leading paradigm in the study of brain diseases. Diffusion tensor imaging (DTI) allows testing the validity and clinical utility of this paradigm on the structural connectivity level. DTI in Alzheimer's disease (AD) suggests a selective impairment of intracortical projecting fiber tracts underlying the functional disorganization of neuronal networks supporting memory and other cognitive functions. These findings have already been tested for their utility as clinical markers of AD in large multicenter studies. Affective disorders, including major depressive disorder (MDD) and bipolar disorder (BP), show a high comorbidity with AD in geriatric populations and may even have a pathogenetic overlap with AD. DTI studies in MDD and BP are still limited to small-scale monocenter studies, revealing subtle abnormalities in cortico-subcortial networks associated with affect regulation and reward/aversion control. The clinical utility of these findings remains to be further explored. The present paper presents the methodological background of diffusion imaging, including DTI and diffusion spectrum imaging, and discusses key findings in AD and affective disorders. The results of our review strongly point toward the necessity of large-scale multicenter multimodal transnosological networks to study the structural and functional basis of neuronal disconnection underlying different neuropsychiatric diseases. PMID:24595744

  10. Factors affecting accuracy and precision in PET volume imaging

    SciTech Connect

    Karp, J.S.; Daube-Witherspoon, M.E.; Muehllehner, G. )

    1991-03-01

    Volume imaging positron emission tomographic (PET) scanners with no septa and a large axial acceptance angle offer several advantages over multiring PET scanners. A volume imaging scanner combines high sensitivity with fine axial sampling and spatial resolution. The fine axial sampling minimizes the partial volume effect, which affects the measured concentration of an object. Even if the size of an object is large compared to the slice spacing in a multiring scanner, significant variation in the concentration is measured as a function of the axial position of the object. With a volume imaging scanner, it is necessary to use a three-dimensional reconstruction algorithm in order to avoid variations in the axial resolution as a function of the distance from the center of the scanner. In addition, good energy resolution is needed in order to use a high energy threshold to reduce the coincident scattered radiation.

  11. The influence of statistical variations on image quality

    NASA Astrophysics Data System (ADS)

    Hultgren, Bror; Hertel, Dirk; Bullitt, Julian

    2006-01-01

    For more than thirty years imaging scientists have constructed metrics to predict psychovisually perceived image quality. Such metrics are based on a set of objectively measurable basis functions such as Noise Power Spectrum (NPS), Modulation Transfer Function (MTF), and characteristic curves of tone and color reproduction. Although these basis functions constitute a set of primitives that fully describe an imaging system from the standpoint of information theory, we found that in practical imaging systems the basis functions themselves are determined by system-specific primitives, i.e. technology parameters. In the example of a printer, MTF and NPS are largely determined by dot structure. In addition MTF is determined by color registration, and NPS by streaking and banding. Since any given imaging system is only a single representation of a class of more or less identical systems, the family of imaging systems and the single system are not described by a unique set of image primitives. For an image produced by a given imaging system, the set of image primitives describing that particular image will be a singular instantiation of the underlying statistical distribution of that primitive. If we know precisely the set of imaging primitives that describe the given image we should be able to predict its image quality. Since only the distributions are known, we can only predict the distribution in image quality for a given image as produced by the larger class of 'identical systems'. We will demonstrate the combinatorial effect of the underlying statistical variations in the image primitives on the objectively measured image quality of a population of printers as well as on the perceived image quality of a set of test images. We also will discuss the choice of test image sets and impact of scene content on the distribution of perceived image quality.

  12. TU-F-9A-01: Balancing Image Quality and Dose in Radiography

    SciTech Connect

    Peck, D; Pasciak, A

    2014-06-15

    Emphasis is often placed on minimizing radiation dose in diagnostic imaging without a complete consideration of the effect on image quality, especially those that affect diagnostic accuracy. This session will include a patient image-based review of diagnostic quantities important to radiologists in conventional radiography, including the effects of body habitus, age, positioning, and the clinical indication of the exam. The relationships between image quality, radiation dose, and radiation risk will be discussed, specifically addressing how these factors are affected by image protocols and acquisition parameters and techniques. This session will also discuss some of the actual and perceived radiation risk associated with diagnostic imaging. Regardless if the probability for radiation-induced cancer is small, the fear associated with radiation persists. Also when a risk has a benefit to an individual or to society, the risk may be justified with respect to the benefit. But how do you convey the risks and the benefits to people? This requires knowledge of how people perceive risk and how to communicate the risk and the benefit to different populations. In this presentation the sources of errors in estimating risk from radiation and some methods used to convey risks are reviewed. Learning Objectives: Understand the image quality metrics that are clinically relevant to radiologists. Understand how acquisition parameters and techniques affect image quality and radiation dose in conventional radiology. Understand the uncertainties in estimates of radiation risk from imaging exams. Learn some methods for effectively communicating radiation risk to the public.

  13. Quality Prediction of Asymmetrically Distorted Stereoscopic 3D Images.

    PubMed

    Wang, Jiheng; Rehman, Abdul; Zeng, Kai; Wang, Shiqi; Wang, Zhou

    2015-11-01

    Objective quality assessment of distorted stereoscopic images is a challenging problem, especially when the distortions in the left and right views are asymmetric. Existing studies suggest that simply averaging the quality of the left and right views well predicts the quality of symmetrically distorted stereoscopic images, but generates substantial prediction bias when applied to asymmetrically distorted stereoscopic images. In this paper, we first build a database that contains both single-view and symmetrically and asymmetrically distorted stereoscopic images. We then carry out a subjective test, where we find that the quality prediction bias of the asymmetrically distorted images could lean toward opposite directions (overestimate or underestimate), depending on the distortion types and levels. Our subjective test also suggests that eye dominance effect does not have strong impact on the visual quality decisions of stereoscopic images. Furthermore, we develop an information content and divisive normalization-based pooling scheme that improves upon structural similarity in estimating the quality of single-view images. Finally, we propose a binocular rivalry-inspired multi-scale model to predict the quality of stereoscopic images from that of the single-view images. Our results show that the proposed model, without explicitly identifying image distortion types, successfully eliminates the prediction bias, leading to significantly improved quality prediction of the stereoscopic images. PMID:26087491

  14. LANDSAT-4 image data quality analysis

    NASA Technical Reports Server (NTRS)

    Anuta, P. E. (Principal Investigator)

    1982-01-01

    Work done on evaluating the geometric and radiometric quality of early LANDSAT-4 sensor data is described. Band to band and channel to channel registration evaluations were carried out using a line correlator. Visual blink comparisons were run on an image display to observe band to band registration over 512 x 512 pixel blocks. The results indicate a .5 pixel line misregistration between the 1.55 to 1.75, 2.08 to 2.35 micrometer bands and the first four bands. Also a four 30M line and column misregistration of the thermal IR band was observed. Radiometric evaluation included mean and variance analysis of individual detectors and principal components analysis. Results indicate that detector bias for all bands is very close or within tolerance. Bright spots were observed in the thermal IR band on an 18 line by 128 pixel grid. No explanation for this was pursued. The general overall quality of the TM was judged to be very high.

  15. Learning to rank for blind image quality assessment.

    PubMed

    Gao, Fei; Tao, Dacheng; Gao, Xinbo; Li, Xuelong

    2015-10-01

    Blind image quality assessment (BIQA) aims to predict perceptual image quality scores without access to reference images. State-of-the-art BIQA methods typically require subjects to score a large number of images to train a robust model. However, subjective quality scores are imprecise, biased, and inconsistent, and it is challenging to obtain a large-scale database, or to extend existing databases, because of the inconvenience of collecting images, training the subjects, conducting subjective experiments, and realigning human quality evaluations. To combat these limitations, this paper explores and exploits preference image pairs (PIPs) such as the quality of image Ia is better than that of image Ib for training a robust BIQA model. The preference label, representing the relative quality of two images, is generally precise and consistent, and is not sensitive to image content, distortion type, or subject identity; such PIPs can be generated at a very low cost. The proposed BIQA method is one of learning to rank. We first formulate the problem of learning the mapping from the image features to the preference label as one of classification. In particular, we investigate the utilization of a multiple kernel learning algorithm based on group lasso to provide a solution. A simple but effective strategy to estimate perceptual image quality scores is then presented. Experiments show that the proposed BIQA method is highly effective and achieves a performance comparable with that of state-of-the-art BIQA algorithms. Moreover, the proposed method can be easily extended to new distortion categories. PMID:25616080

  16. Food quality assessment by NIR hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Whitworth, Martin B.; Millar, Samuel J.; Chau, Astor

    2010-04-01

    Near infrared reflectance (NIR) spectroscopy is well established in the food industry for rapid compositional analysis of bulk samples. NIR hyperspectral imaging provides new opportunities to measure the spatial distribution of components such as moisture and fat, and to identify and measure specific regions of composite samples. An NIR hyperspectral imaging system has been constructed for food research applications, incorporating a SWIR camera with a cooled 14 bit HgCdTe detector and N25E spectrograph (Specim Ltd, Finland). Samples are scanned in a pushbroom mode using a motorised stage. The system has a spectral resolution of 256 pixels covering a range of 970-2500 nm and a spatial resolution of 320 pixels covering a swathe adjustable from 8 to 300 mm. Images are acquired at a rate of up to 100 lines s-1, enabling samples to be scanned within a few seconds. Data are captured using SpectralCube software (Specim) and analysed using ENVI and IDL (ITT Visual Information Solutions). Several food applications are presented. The strength of individual absorbance bands enables the distribution of particular components to be assessed. Examples are shown for detection of added gluten in wheat flour and to study the effect of processing conditions on fat distribution in chips/French fries. More detailed quantitative calibrations have been developed to study evolution of the moisture distribution in baguettes during storage at different humidities, to assess freshness of fish using measurements of whole cod and fillets, and for prediction of beef quality by identification and separate measurement of lean and fat regions.

  17. Focal Length Affects Depicted Shape and Perception of Facial Images

    PubMed Central

    Třebický, Vít; Fialová, Jitka; Kleisner, Karel; Havlíček, Jan

    2016-01-01

    Static photographs are currently the most often employed stimuli in research on social perception. The method of photograph acquisition might affect the depicted subject’s facial appearance and thus also the impression of such stimuli. An important factor influencing the resulting photograph is focal length, as different focal lengths produce various levels of image distortion. Here we tested whether different focal lengths (50, 85, 105 mm) affect depicted shape and perception of female and male faces. We collected three portrait photographs of 45 (22 females, 23 males) participants under standardized conditions and camera setting varying only in the focal length. Subsequently, the three photographs from each individual were shown on screen in a randomized order using a 3-alternative forced-choice paradigm. The images were judged for attractiveness, dominance, and femininity/masculinity by 369 raters (193 females, 176 males). Facial width-to-height ratio (fWHR) was measured from each photograph and overall facial shape was analysed employing geometric morphometric methods (GMM). Our results showed that photographs taken with 50 mm focal length were rated as significantly less feminine/masculine, attractive, and dominant compared to the images taken with longer focal lengths. Further, shorter focal lengths produced faces with smaller fWHR. Subsequent GMM revealed focal length significantly affected overall facial shape of the photographed subjects. Thus methodology of photograph acquisition, focal length in this case, can significantly affect results of studies using photographic stimuli perhaps due to different levels of perspective distortion that influence shapes and proportions of morphological traits. PMID:26894832

  18. Focal Length Affects Depicted Shape and Perception of Facial Images.

    PubMed

    Třebický, Vít; Fialová, Jitka; Kleisner, Karel; Havlíček, Jan

    2016-01-01

    Static photographs are currently the most often employed stimuli in research on social perception. The method of photograph acquisition might affect the depicted subject's facial appearance and thus also the impression of such stimuli. An important factor influencing the resulting photograph is focal length, as different focal lengths produce various levels of image distortion. Here we tested whether different focal lengths (50, 85, 105 mm) affect depicted shape and perception of female and male faces. We collected three portrait photographs of 45 (22 females, 23 males) participants under standardized conditions and camera setting varying only in the focal length. Subsequently, the three photographs from each individual were shown on screen in a randomized order using a 3-alternative forced-choice paradigm. The images were judged for attractiveness, dominance, and femininity/masculinity by 369 raters (193 females, 176 males). Facial width-to-height ratio (fWHR) was measured from each photograph and overall facial shape was analysed employing geometric morphometric methods (GMM). Our results showed that photographs taken with 50 mm focal length were rated as significantly less feminine/masculine, attractive, and dominant compared to the images taken with longer focal lengths. Further, shorter focal lengths produced faces with smaller fWHR. Subsequent GMM revealed focal length significantly affected overall facial shape of the photographed subjects. Thus methodology of photograph acquisition, focal length in this case, can significantly affect results of studies using photographic stimuli perhaps due to different levels of perspective distortion that influence shapes and proportions of morphological traits. PMID:26894832

  19. Biosolids applications affect runoff water quality following forest fire.

    PubMed

    Meyer, V F; Redente, E F; Barbarick, K A; Brobst, R

    2001-01-01

    Soil erosion and nutrient losses are great concerns following forest wildfires. Biosolids application might enhance revegetation efforts while reducing soil erodibility. Consequently, we applied Denver Metro Wastewater District composted biosolids at rates of 0, 40, and 80 Mg ha(-1) to a severely burned, previously forested site near Buffalo Creek, CO to increase plant cover and growth. Soils were classified as Ustorthents, Ustochrepts, and Haploborols. Simulated rainfall was applied for 30 min at a rate of 100 mm h(-1) to 3- x 10-m paired plots. Biosolids application rates did not significantly affect mean total runoff (p < 0.05). Sediment concentrations were significantly greater (p < 0.05) from the control plots compared with the plots that had received the 80 Mg biosolids ha(-1) rate. Biosolids application rate had mixed effects on water-quality constituents; however, concentrations of all runoff constituents for all treatment rates were below levels recommended for drinking water standards, except Pb. Biosolids application to this site increased plant cover, which should provide erosion control. PMID:11577857

  20. Image Settings Affecting Nuchal Translucency Measurement Using Volume NT™ Software

    PubMed Central

    Cho, Hee Young; Kim, Young Han; Park, Yong Won; Kim, Sung Yoon; Lee, Kwang Hee; Yoo, Joon Sang

    2015-01-01

    Purpose To evaluate the effects of the deviation from the mid-sagittal plane, fetal image size, tissue harmonic imaging (THI), and speckle reduction filter (SRF) on the measurement of the nuchal translucency (NT) thickness using Volume NT™ software. Materials and Methods In 79 pregnant women, NT was measured using Volume NT™. Firstly, the three-dimensional volumes were categorized based on the angle of deviation in 10° intervals from the mid-sagittal plane. Secondly, the operator downsized the fetal image to less than 50% of the screen (Method A) and by magnifying the image (Method B). Next, the image was magnified until the fetal head and thorax occupied 75% of the screen, and the NT was measured (Method C). Lastly, NT values were acquired with THI and SRF functions on, with each function alternately on, and with both functions off. Results The mean differences in NT measurements were -0.09 mm (p<0.01) between two-dimensional (2D) and a deviation of 31-40° and -0.10 mm (p<0.01) between 2D and 41-50°. The intraclass correlation coefficients (ICC) for 2D-NT and NT according to image size were 0.858, 0.923, and 0.928 for methods A, B, and C, respectively. The ICC for 2D-NT and NT with respect to the THI and SRF were 0.786, 0.761, 0.740, and 0.731 with both functions on, THI only, SRF only, and with both functions off, respectively. Conclusion NT measurements made using Volume NT™ are affected by angle deviation from the mid-sagittal plane and fetal image size. Additionally, the highest correlation with 2D-NT was achieved when THI and SRF functions were used. PMID:26256978

  1. How does angular resolution affect diffusion imaging measures?

    PubMed

    Zhan, Liang; Leow, Alex D; Jahanshad, Neda; Chiang, Ming-Chang; Barysheva, Marina; Lee, Agatha D; Toga, Arthur W; McMahon, Katie L; de Zubicaray, Greig I; Wright, Margaret J; Thompson, Paul M

    2010-01-15

    A key question in diffusion imaging is how many diffusion-weighted images suffice to provide adequate signal-to-noise ratio (SNR) for studies of fiber integrity. Motion, physiological effects, and scan duration all affect the achievable SNR in real brain images, making theoretical studies and simulations only partially useful. We therefore scanned 50 healthy adults with 105-gradient high-angular resolution diffusion imaging (HARDI) at 4T. From gradient image subsets of varying size (6images was 9.13 for GA and tGA, 10.57 for FA, 9.17 for RA, and 26 for MD and VR. In orientation density functions modeling the HARDI signal as a continuous mixture of tensors, the diffusion profile reconstruction accuracy rose rapidly with additional gradients. These plots may help in making trade-off decisions when designing diffusion imaging protocols. PMID:19819339

  2. Retinal Image Quality during Accommodation in Adult Myopic Eyes

    PubMed Central

    Sreenivasan, Vidhyapriya; Aslakson, Emily; Kornaus, Andrew; Thibos, Larry N.

    2014-01-01

    Purpose Reduced retinal image contrast produced by accommodative lag is implicated with myopia development. Here, we measure accommodative error and retinal image quality from wavefront aberrations in myopes and emmetropes when they perform visually demanding and naturalistic tasks. Methods Wavefront aberrations were measured in 10 emmetropic and 11 myopic adults at three distances (100, 40, and 20 cm) while performing four tasks (monocular acuity, binocular acuity, reading, and movie watching). For the acuity tasks, measurements of wavefront error were obtained near the end point of the acuity experiment. Refractive state was defined as the target vergence that optimizes image quality using a visual contrast metric (VSMTF) computed from wavefront errors. Results Accommodation was most accurate (and image quality best) during binocular acuity whereas accommodation was least accurate (and image quality worst) while watching a movie. When viewing distance was reduced, accommodative lag increased and image quality (as quantified by VSMTF) declined for all tasks in both refractive groups. For any given viewing distance, computed image quality was consistently worse in myopes than in emmetropes, more so for the acuity than for reading/movie watching. Although myopes showed greater lags and worse image quality for the acuity experiments compared to emmetropes, acuity was not measurably worse in myopes compared to emmetropes. Conclusions Retinal image quality present when performing a visually demanding task (e.g., during clinical examination) is likely to be greater than for less demanding tasks (e.g., reading/movie watching). Although reductions in image quality lead to reductions in acuity, the image quality metric VSMTF is not necessarily an absolute indicator of visual performance because myopes achieved slightly better acuity than emmetropes despite showing greater lags and worse image quality. Reduced visual contrast in myopes compared to emmetropes is consistent

  3. Perceptual Quality Assessment for Multi-Exposure Image Fusion.

    PubMed

    Ma, Kede; Zeng, Kai; Wang, Zhou

    2015-11-01

    Multi-exposure image fusion (MEF) is considered an effective quality enhancement technique widely adopted in consumer electronics, but little work has been dedicated to the perceptual quality assessment of multi-exposure fused images. In this paper, we first build an MEF database and carry out a subjective user study to evaluate the quality of images generated by different MEF algorithms. There are several useful findings. First, considerable agreement has been observed among human subjects on the quality of MEF images. Second, no single state-of-the-art MEF algorithm produces the best quality for all test images. Third, the existing objective quality models for general image fusion are very limited in predicting perceived quality of MEF images. Motivated by the lack of appropriate objective models, we propose a novel objective image quality assessment (IQA) algorithm for MEF images based on the principle of the structural similarity approach and a novel measure of patch structural consistency. Our experimental results on the subjective database show that the proposed model well correlates with subjective judgments and significantly outperforms the existing IQA models for general image fusion. Finally, we demonstrate the potential application of the proposed model by automatically tuning the parameters of MEF algorithms. PMID:26068317

  4. Quantitative image quality evaluation for cardiac CT reconstructions

    NASA Astrophysics Data System (ADS)

    Tseng, Hsin-Wu; Fan, Jiahua; Kupinski, Matthew A.; Balhorn, William; Okerlund, Darin R.

    2016-03-01

    Maintaining image quality in the presence of motion is always desirable and challenging in clinical Cardiac CT imaging. Different image-reconstruction algorithms are available on current commercial CT systems that attempt to achieve this goal. It is widely accepted that image-quality assessment should be task-based and involve specific tasks, observers, and associated figures of merits. In this work, we developed an observer model that performed the task of estimating the percentage of plaque in a vessel from CT images. We compared task performance of Cardiac CT image data reconstructed using a conventional FBP reconstruction algorithm and the SnapShot Freeze (SSF) algorithm, each at default and optimal reconstruction cardiac phases. The purpose of this work is to design an approach for quantitative image-quality evaluation of temporal resolution for Cardiac CT systems. To simulate heart motion, a moving coronary type phantom synchronized with an ECG signal was used. Three different percentage plaques embedded in a 3 mm vessel phantom were imaged multiple times under motion free, 60 bpm, and 80 bpm heart rates. Static (motion free) images of this phantom were taken as reference images for image template generation. Independent ROIs from the 60 bpm and 80 bpm images were generated by vessel tracking. The observer performed estimation tasks using these ROIs. Ensemble mean square error (EMSE) was used as the figure of merit. Results suggest that the quality of SSF images is superior to the quality of FBP images in higher heart-rate scans.

  5. Objective Image-Quality Assessment for High-Resolution Photospheric Images by Median Filter-Gradient Similarity

    NASA Astrophysics Data System (ADS)

    Deng, Hui; Zhang, Dandan; Wang, Tianyu; Ji, Kaifan; Wang, Feng; Liu, Zhong; Xiang, Yongyuan; Jin, Zhenyu; Cao, Wenda

    2015-05-01

    All next-generation ground-based and space-based solar telescopes require a good quality-assessment metric to evaluate their imaging performance. In this paper, a new image quality metric, the median filter-gradient similarity (MFGS) is proposed for photospheric images. MFGS is a no-reference/blind objective image-quality metric (IQM) by a measurement result between 0 and 1 and has been performed on short-exposure photospheric images captured by the New Vacuum Solar Telescope (NVST) of the Fuxian Solar Observatory and by the Solar Optical Telescope (SOT) onboard the Hinode satellite, respectively. The results show that (1) the measured value of the MFGS changes monotonically from 1 to 0 with degradation of image quality; (2) there exists a linear correlation between the measured values of the MFGS and the root-mean-square contrast (RMS-contrast) of the granulation; (3) the MFGS is less affected by the image contents than the granular RMS-contrast. Overall, the MFGS is a good alternative for the quality assessment of photospheric images.

  6. How Does Premarital Cohabitation Affect Trajectories of Marital Quality?

    ERIC Educational Resources Information Center

    Tach, Laura; Halpern-Meekin, Sarah

    2009-01-01

    We investigate the link between premarital cohabitation and trajectories of subsequent marital quality using random effects growth curve models and repeated measures of marital quality from married women in the NLSY-79 (N = 3,598). We find that premarital cohabitors experience lower quality marital relationships on average, but this is driven by…

  7. Financial Health of Child Care Facilities Affects Quality of Care.

    ERIC Educational Resources Information Center

    Brower, Mary R.; Sull, Theresa M.

    2003-01-01

    Contends that child care facility owners, boards of directors, staff, and parents need to focus on financial management, as poor financial health compromises the quality of care for children. Specifically addresses the issues of: (1) concern for providing high quality child care; (2) the connection between quality and money; and (3) strengthening…

  8. Contrast sensitivity function calibration based on image quality prediction

    NASA Astrophysics Data System (ADS)

    Han, Yu; Cai, Yunze

    2014-11-01

    Contrast sensitivity functions (CSFs) describe visual stimuli based on their spatial frequency. However, CSF calibration is limited by the size of the sample collection and this remains an open issue. In this study, we propose an approach for calibrating CSFs that is based on the hypothesis that a precise CSF model can accurately predict image quality. Thus, CSF calibration is regarded as the inverse problem of image quality prediction according to our hypothesis. A CSF could be calibrated by optimizing the performance of a CSF-based image quality metric using a database containing images with known quality. Compared with the traditional method, this would reduce the work involved in sample collection dramatically. In the present study, we employed three image databases to optimize some existing CSF models. The experimental results showed that the performance of a three-parameter CSF model was better than that of other models. The results of this study may be helpful in CSF and image quality research.

  9. Research iris serial images quality assessment method based on HVS

    NASA Astrophysics Data System (ADS)

    Li, Zhi-hui; Zhang, Chang-hai; Ming, Xing; Zhao, Yong-hua

    2006-01-01

    Iris recognition can be widely used in security and customs, and it provides superiority security than other human feature recognition such as fingerprint, face and so on. The iris image quality is crucial to recognition effect. Accordingly reliable image quality assessments are necessary for evaluating iris image quality. However, there haven't uniformly criterion to Image quality assessment. Image quality assessment have Objective and Subjective Evaluation methods, In practice, However Subjective Evaluation method is fussy and doesn't effective on iris recognition. Objective Evaluation method should be used in iris recognition. According to human visual system model (HVS) Multi-scale and selectivity characteristic, it presents a new iris Image quality assessment method. In the paper, ROI is found and wavelet transform zero-crossing is used to find Multi-scale edge, and Multi-scale fusion measure is used to assess iris image quality. In experiment, Objective and Subjective Evaluation methods are used to assess iris images. From the results, the method is effectively to iris image quality assessment.

  10. Is image quality a function of contrast perception?

    NASA Astrophysics Data System (ADS)

    Haun, Andrew M.; Peli, Eli

    2013-03-01

    In this retrospective we trace in broad strokes the development of image quality measures based on the study of the early stages of the human visual system (HVS), where contrast encoding is fundamental. We find that while presenters at the Human Vision and Electronic Imaging meetings have frequently strived to find points of contact between the study of human contrast psychophysics and the development of computer vision and image quality algorithms. Progress has not always been made on these terms, although indirect impact of vision science on more recent image quality metrics can be observed.

  11. New image quality assessment method using wavelet leader pyramids

    NASA Astrophysics Data System (ADS)

    Chen, Xiaolin; Yang, Xiaokang; Zheng, Shibao; Lin, Weiyao; Zhang, Rui; Zhai, Guangtao

    2011-06-01

    In this paper, we propose a wave leader pyramids based Visual Information Fidelity method for image quality assessment. Motivated by the observations that the human vision systems (HVS) are more sensitive to edge and contour regions and that the human visual sensitivity varies with spatial frequency, we first introduce the two-dimensional wavelet leader pyramids to robustly extract the multiscale information of edges. Based on the wavelet leader pyramids, we further propose a visual information fidelity metric to evaluate the quality of images by quantifying the information loss between the original and the distorted images. Experimental results show that our method outperforms many state-of-the-art image quality metrics.

  12. Elevated atmospheric carbon dioxide in agroecosystems affects groundwater quality

    SciTech Connect

    Torbert, H.A.; Prior, S.A.; Rogers, H.H.; Schlesinger, W.H.; Mullins, G.L.; Runion, G.B.

    1996-07-01

    Increasing atmospheric carbon dioxide (CO{sub 2}) concentration has led to concerns about global changes to the environment. One area of global change that has not been addressed is the effect of elevated atmospheric CO{sub 2} on groundwater quality below agroecosystems. Elevated CO{sub 2} concentration alterations of plant growth and C/N ratios may modify C and N cycling in soil and affect nitrate (NO{sub 3}{sup {minus}}) leaching to groundwater. This study was conducted to examine the effects of a legume (soybean [Glycine max (L.) Merr.]) and a nonlegume (grain sorghum [Sorghum bicolor (L.) Moench]) CO{sub 2}-enriched agroecosystems on NO{sub 3}{sup {minus}} movement below the root zone in a Blanton loamy sand (loamy siliceous, thermic, Grossarenic Paleudults). The study was a split-plot design replicated three times with plant species (soybean and grain sorghum) as the main plots and CO{sub 2} concentration ({approximately}360 and {approximately}720 {mu}L L{sup {minus}1} CO{sub 2}) as subplots using open-top field chambers. Fertilizer application was made with {sup 15}N-depleted NH{sub 4}NO{sub 3} to act as a fertilizer tracer. Soil solution samples were collected weekly at 90-cm depth for a 2-yr period and monitored for NO{sub 3}{sup {minus}}-N concentrations. Isotope analysis of soil solution indicated that the decomposition of organic matter was the primary source of No{sub 3}{sup {minus}}-N in soil solution below the root zone through most of the monitoring period. Significant differences were observed for NO{sub 3}{sup {minus}}-N concentrations between soybean and grain sorghum, with soybean having the higher NO{sub 3}{sup {minus}}-N concentration. Elevated CO{sub 2} increased total dry weight, total N content, and C/N ratio of residue returned to soil in both years. Elevated CO{sub 2} significantly decreased NO{sub 3}{sup {minus}}-N concentrations below the root zone in both soybean and grain sorghum. 37 refs., 2 figs., 2 tabs.

  13. Image quality assessment for CT used on small animals

    NASA Astrophysics Data System (ADS)

    Cisneros, Isabela Paredes; Agulles-Pedrós, Luis

    2016-07-01

    Image acquisition on a CT scanner is nowadays necessary in almost any kind of medical study. Its purpose, to produce anatomical images with the best achievable quality, implies the highest diagnostic radiation exposure to patients. Image quality can be measured quantitatively based on parameters such as noise, uniformity and resolution. This measure allows the determination of optimal parameters of operation for the scanner in order to get the best diagnostic image. A human Phillips CT scanner is the first one minded for veterinary-use exclusively in Colombia. The aim of this study was to measure the CT image quality parameters using an acrylic phantom and then, using the computational tool MatLab, determine these parameters as a function of current value and window of visualization, in order to reduce dose delivery by keeping the appropriate image quality.

  14. Dynamic flat panel detector versus image intensifier in cardiac imaging: dose and image quality

    NASA Astrophysics Data System (ADS)

    Vano, E.; Geiger, B.; Schreiner, A.; Back, C.; Beissel, J.

    2005-12-01

    The practical aspects of the dosimetric and imaging performance of a digital x-ray system for cardiology procedures were evaluated. The system was configured with an image intensifier (II) and later upgraded to a dynamic flat panel detector (FD). Entrance surface air kerma (ESAK) to phantoms of 16, 20, 24 and 28 cm of polymethyl methacrylate (PMMA) and the image quality of a test object were measured. Images were evaluated directly on the monitor and with numerical methods (noise and signal-to-noise ratio). Information contained in the DICOM header for dosimetry audit purposes was also tested. ESAK values per frame (or kerma rate) for the most commonly used cine and fluoroscopy modes for different PMMA thicknesses and for field sizes of 17 and 23 cm for II, and 20 and 25 cm for FD, produced similar results in the evaluated system with both technologies, ranging between 19 and 589 µGy/frame (cine) and 5 and 95 mGy min-1 (fluoroscopy). Image quality for these dose settings was better for the FD version. The 'study dosimetric report' is comprehensive, and its numerical content is sufficiently accurate. There is potential in the future to set those systems with dynamic FD to lower doses than are possible in the current II versions, especially for digital cine runs, or to benefit from improved image quality.

  15. Quaternion structural similarity: a new quality index for color images.

    PubMed

    Kolaman, Amir; Yadid-Pecht, Orly

    2012-04-01

    One of the most important issues for researchers developing image processing algorithms is image quality. Methodical quality evaluation, by showing images to several human observers, is slow, expensive, and highly subjective. On the other hand, a visual quality matrix (VQM) is a fast, cheap, and objective tool for evaluating image quality. Although most VQMs are good in predicting the quality of an image degraded by a single degradation, they poorly perform for a combination of two degradations. An example for such degradation is the color crosstalk (CTK) effect, which introduces blur with desaturation. CTK is expected to become a bigger issue in image quality as the industry moves toward smaller sensors. In this paper, we will develop a VQM that will be able to better evaluate the quality of an image degraded by a combined blur/desaturation degradation and perform as well as other VQMs on single degradations such as blur, compression, and noise. We show why standard scalar techniques are insufficient to measure a combined blur/desaturation degradation and explain why a vectorial approach is better suited. We introduce quaternion image processing (QIP), which is a true vectorial approach and has many uses in the fields of physics and engineering. Our new VQM is a vectorial expansion of structure similarity using QIP, which gave it its name-Quaternion Structural SIMilarity (QSSIM). We built a new database of a combined blur/desaturation degradation and conducted a quality survey with human subjects. An extensive comparison between QSSIM and other VQMs on several image quality databases-including our new database-shows the superiority of this new approach in predicting visual quality of color images. PMID:22203713

  16. Effect of image quality on calcification detection in digital mammography

    SciTech Connect

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-06-15

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  17. Effect of image quality on calcification detection in digital mammography

    PubMed Central

    Warren, Lucy M.; Mackenzie, Alistair; Cooke, Julie; Given-Wilson, Rosalind M.; Wallis, Matthew G.; Chakraborty, Dev P.; Dance, David R.; Bosmans, Hilde; Young, Kenneth C.

    2012-01-01

    Purpose: This study aims to investigate if microcalcification detection varies significantly when mammographic images are acquired using different image qualities, including: different detectors, dose levels, and different image processing algorithms. An additional aim was to determine how the standard European method of measuring image quality using threshold gold thickness measured with a CDMAM phantom and the associated limits in current EU guidelines relate to calcification detection. Methods: One hundred and sixty two normal breast images were acquired on an amorphous selenium direct digital (DR) system. Microcalcification clusters extracted from magnified images of slices of mastectomies were electronically inserted into half of the images. The calcification clusters had a subtle appearance. All images were adjusted using a validated mathematical method to simulate the appearance of images from a computed radiography (CR) imaging system at the same dose, from both systems at half this dose, and from the DR system at quarter this dose. The original 162 images were processed with both Hologic and Agfa (Musica-2) image processing. All other image qualities were processed with Agfa (Musica-2) image processing only. Seven experienced observers marked and rated any identified suspicious regions. Free response operating characteristic (FROC) and ROC analyses were performed on the data. The lesion sensitivity at a nonlesion localization fraction (NLF) of 0.1 was also calculated. Images of the CDMAM mammographic test phantom were acquired using the automatic setting on the DR system. These images were modified to the additional image qualities used in the observer study. The images were analyzed using automated software. In order to assess the relationship between threshold gold thickness and calcification detection a power law was fitted to the data. Results: There was a significant reduction in calcification detection using CR compared with DR: the alternative FROC

  18. Image quality and dose efficiency of high energy phase sensitive x-ray imaging: Phantom studies

    PubMed Central

    Wong, Molly Donovan; Wu, Xizeng; Liu, Hong

    2014-01-01

    The goal of this preliminary study was to perform an image quality comparison of high energy phase sensitive imaging with low energy conventional imaging at similar radiation doses. The comparison was performed with the following phantoms: American College of Radiology (ACR), contrast-detail (CD), acrylic edge and tissue-equivalent. Visual comparison of the phantom images indicated comparable or improved image quality for all phantoms. Quantitative comparisons were performed through ACR and CD observer studies, both of which indicated higher image quality in the high energy phase sensitive images. The results of this study demonstrate the ability of high energy phase sensitive imaging to overcome existing challenges with the clinical implementation of phase contrast imaging and improve the image quality for a similar radiation dose as compared to conventional imaging near typical mammography energies. In addition, the results illustrate the capability of phase sensitive imaging to sustain the image quality improvement at high x-ray energies and for – breast – simulating phantoms, both of which indicate the potential to benefit fields such as mammography. Future studies will continue to investigate the potential for dose reduction and image quality improvement provided by high energy phase sensitive contrast imaging. PMID:24865208

  19. Damage and quality assessment in wheat by NIR hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Delwiche, Stephen R.; Kim, Moon S.; Dong, Yanhong

    2010-04-01

    Fusarium head blight is a fungal disease that affects the world's small grains, such as wheat and barley. Attacking the spikelets during development, the fungus causes a reduction of yield and grain of poorer processing quality. It also is a health concern because of the secondary metabolite, deoxynivalenol, which often accompanies the fungus. While chemical methods exist to measure the concentration of the mycotoxin and manual visual inspection is used to ascertain the level of Fusarium damage, research has been active in developing fast, optically based techniques that can assess this form of damage. In the current study a near-infrared (1000-1700 nm) hyperspectral image system was assembled and applied to Fusarium-damaged kernel recognition. With anticipation of an eventual multispectral imaging system design, 5 wavelengths were manually selected from a pool of 146 images as the most promising, such that when combined in pairs or triplets, Fusarium damage could be identified. We present the results of two pairs of wavelengths [(1199, 1474 nm) and (1315, 1474 nm)] whose reflectance values produced adequate separation of kernels of healthy appearance (i.e., asymptomatic condition) from kernels possessing Fusarium damage.

  20. Image processing system performance prediction and product quality evaluation

    NASA Technical Reports Server (NTRS)

    Stein, E. K.; Hammill, H. B. (Principal Investigator)

    1976-01-01

    The author has identified the following significant results. A new technique for image processing system performance prediction and product quality evaluation was developed. It was entirely objective, quantitative, and general, and should prove useful in system design and quality control. The technique and its application to determination of quality control procedures for the Earth Resources Technology Satellite NASA Data Processing Facility are described.

  1. A new assessment method for image fusion quality

    NASA Astrophysics Data System (ADS)

    Li, Liu; Jiang, Wanying; Li, Jing; Yuchi, Ming; Ding, Mingyue; Zhang, Xuming

    2013-03-01

    Image fusion quality assessment plays a critically important role in the field of medical imaging. To evaluate image fusion quality effectively, a lot of assessment methods have been proposed. Examples include mutual information (MI), root mean square error (RMSE), and universal image quality index (UIQI). These image fusion assessment methods could not reflect the human visual inspection effectively. To address this problem, we have proposed a novel image fusion assessment method which combines the nonsubsampled contourlet transform (NSCT) with the regional mutual information in this paper. In this proposed method, the source medical images are firstly decomposed into different levels by the NSCT. Then the maximum NSCT coefficients of the decomposed directional images at each level are obtained to compute the regional mutual information (RMI). Finally, multi-channel RMI is computed by the weighted sum of the obtained RMI values at the various levels of NSCT. The advantage of the proposed method lies in the fact that the NSCT can represent image information using multidirections and multi-scales and therefore it conforms to the multi-channel characteristic of human visual system, leading to its outstanding image assessment performance. The experimental results using CT and MRI images demonstrate that the proposed assessment method outperforms such assessment methods as MI and UIQI based measure in evaluating image fusion quality and it can provide consistent results with human visual assessment.

  2. Raman chemical imaging system for food safety and quality inspection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging technique combines Raman spectroscopy and digital imaging to visualize composition and structure of a target, and it offers great potential for food safety and quality research. In this study, a laboratory-based Raman chemical imaging platform was designed and developed. The i...

  3. Wintering performance and how it affects carcass quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Environmental variation undoubtedly can have the most significant impact on livestock performance in forage based production systems. Fluctuations in temperature and precipitation influence herbage production and quality, maintenance requirements and intake. Producers of “forage system” products h...

  4. Automated quality assessment in three-dimensional breast ultrasound images.

    PubMed

    Schwaab, Julia; Diez, Yago; Oliver, Arnau; Martí, Robert; van Zelst, Jan; Gubern-Mérida, Albert; Mourri, Ahmed Bensouda; Gregori, Johannes; Günther, Matthias

    2016-04-01

    Automated three-dimensional breast ultrasound (ABUS) is a valuable adjunct to x-ray mammography for breast cancer screening of women with dense breasts. High image quality is essential for proper diagnostics and computer-aided detection. We propose an automated image quality assessment system for ABUS images that detects artifacts at the time of acquisition. Therefore, we study three aspects that can corrupt ABUS images: the nipple position relative to the rest of the breast, the shadow caused by the nipple, and the shape of the breast contour on the image. Image processing and machine learning algorithms are combined to detect these artifacts based on 368 clinical ABUS images that have been rated manually by two experienced clinicians. At a specificity of 0.99, 55% of the images that were rated as low quality are detected by the proposed algorithms. The areas under the ROC curves of the single classifiers are 0.99 for the nipple position, 0.84 for the nipple shadow, and 0.89 for the breast contour shape. The proposed algorithms work fast and reliably, which makes them adequate for online evaluation of image quality during acquisition. The presented concept may be extended to further image modalities and quality aspects. PMID:27158633

  5. Impact of Computed Tomography Image Quality on Image-Guided Radiation Therapy Based on Soft Tissue Registration

    SciTech Connect

    Morrow, Natalya V.; Lawton, Colleen A.; Qi, X. Sharon; Li, X. Allen

    2012-04-01

    Purpose: In image-guided radiation therapy (IGRT), different computed tomography (CT) modalities with varying image quality are being used to correct for interfractional variations in patient set-up and anatomy changes, thereby reducing clinical target volume to the planning target volume (CTV-to-PTV) margins. We explore how CT image quality affects patient repositioning and CTV-to-PTV margins in soft tissue registration-based IGRT for prostate cancer patients. Methods and Materials: Four CT-based IGRT modalities used for prostate RT were considered in this study: MV fan beam CT (MVFBCT) (Tomotherapy), MV cone beam CT (MVCBCT) (MVision; Siemens), kV fan beam CT (kVFBCT) (CTVision, Siemens), and kV cone beam CT (kVCBCT) (Synergy; Elekta). Daily shifts were determined by manual registration to achieve the best soft tissue agreement. Effect of image quality on patient repositioning was determined by statistical analysis of daily shifts for 136 patients (34 per modality). Inter- and intraobserver variability of soft tissue registration was evaluated based on the registration of a representative scan for each CT modality with its corresponding planning scan. Results: Superior image quality with the kVFBCT resulted in reduced uncertainty in soft tissue registration during IGRT compared with other image modalities for IGRT. The largest interobserver variations of soft tissue registration were 1.1 mm, 2.5 mm, 2.6 mm, and 3.2 mm for kVFBCT, kVCBCT, MVFBCT, and MVCBCT, respectively. Conclusions: Image quality adversely affects the reproducibility of soft tissue-based registration for IGRT and necessitates a careful consideration of residual uncertainties in determining different CTV-to-PTV margins for IGRT using different image modalities.

  6. Retinal image quality assessment through a visual similarity index

    NASA Astrophysics Data System (ADS)

    Pérez, Jorge; Espinosa, Julián; Vázquez, Carmen; Mas, David

    2013-04-01

    Retinal image quality is commonly analyzed through parameters inherited from instrumental optics. These parameters are defined for 'good optics' so they are hard to translate into visual quality metrics. Instead of using point or artificial functions, we propose a quality index that takes into account properties of natural images. These images usually show strong local correlations that help to interpret the image. Our aim is to derive an objective index that quantifies the quality of vision by taking into account the local structure of the scene, instead of focusing on a particular aberration. As we show, this index highly correlates with visual acuity and allows inter-comparison of natural images around the retina. The usefulness of the index is proven through the analysis of real eyes before and after undergoing corneal surgery, which usually are hard to analyze with standard metrics.

  7. Testing scanners for the quality of output images

    NASA Astrophysics Data System (ADS)

    Concepcion, Vicente P.; Nadel, Lawrence D.; D'Amato, Donald P.

    1995-01-01

    Document scanning is the means through which documents are converted to their digital image representation for electronic storage or distribution. Among the types of documents being scanned by government agencies are tax forms, patent documents, office correspondence, mail pieces, engineering drawings, microfilm, archived historical papers, and fingerprint cards. Increasingly, the resulting digital images are used as the input for further automated processing including: conversion to a full-text-searchable representation via machine printed or handwritten (optical) character recognition (OCR), postal zone identification, raster-to-vector conversion, and fingerprint matching. These diverse document images may be bi-tonal, gray scale, or color. Spatial sampling frequencies range from about 200 pixels per inch to over 1,000. The quality of the digital images can have a major effect on the accuracy and speed of any subsequent automated processing, as well as on any human-based processing which may be required. During imaging system design, there is, therefore, a need to specify the criteria by which image quality will be judged and, prior to system acceptance, to measure the quality of images produced. Unfortunately, there are few, if any, agreed-upon techniques for measuring document image quality objectively. In the output images, it is difficult to distinguish image degradation caused by the poor quality of the input paper or microfilm from that caused by the scanning system. We propose several document image quality criteria and have developed techniques for their measurement. These criteria include spatial resolution, geometric image accuracy, (distortion), gray scale resolution and linearity, and temporal and spatial uniformity. The measurement of these criteria requires scanning one or more test targets along with computer-based analyses of the test target images.

  8. No-reference visual quality assessment for image inpainting

    NASA Astrophysics Data System (ADS)

    Voronin, V. V.; Frantc, V. A.; Marchuk, V. I.; Sherstobitov, A. I.; Egiazarian, K.

    2015-03-01

    Inpainting has received a lot of attention in recent years and quality assessment is an important task to evaluate different image reconstruction approaches. In many cases inpainting methods introduce a blur in sharp transitions in image and image contours in the recovery of large areas with missing pixels and often fail to recover curvy boundary edges. Quantitative metrics of inpainting results currently do not exist and researchers use human comparisons to evaluate their methodologies and techniques. Most objective quality assessment methods rely on a reference image, which is often not available in inpainting applications. Usually researchers use subjective quality assessment by human observers. It is difficult and time consuming procedure. This paper focuses on a machine learning approach for no-reference visual quality assessment for image inpainting based on the human visual property. Our method is based on observation that Local Binary Patterns well describe local structural information of the image. We use a support vector regression learned on assessed by human images to predict perceived quality of inpainted images. We demonstrate how our predicted quality value correlates with qualitative opinion in a human observer study. Results are shown on a human-scored dataset for different inpainting methods.

  9. Improvement of image quality by polarization mixing

    NASA Astrophysics Data System (ADS)

    Kasahara, Ryosuke; Itoh, Izumi; Hirai, Hideaki

    2014-03-01

    Information about the polarization of light is valuable because it contains information about the light source illuminating an object, the illumination angle, and the object material. However, polarization information strongly depends on the direction of the light source, and it is difficult to use a polarization image with various recognition algorithms outdoors because the angle of the sun varies. We propose an image enhancement method for utilizing polarization information in many such situations where the light source is not fixed. We take two approaches to overcome this problem. First, we compute an image that is the combination of a polarization image and the corresponding brightness image. Because of the angle of the light source, the polarization contains no information about some scenes. Therefore, it is difficult to use only polarization information in any scene for applications such as object detection. However, if we use a combination of a polarization image and a brightness image, the brightness image can complement the lack of scene information. The second approach is finding features that depend less on the direction of the light source. We propose a method for extracting scene features based on a calculation of the reflection model including polarization effects. A polarization camera that has micro-polarizers on each pixel of the image sensor was built and used for capturing images. We discuss examples that demonstrate the improved visibility of objects by applying our proposed method to, e.g., the visibility of lane markers on wet roads.

  10. Meat quality evaluation by hyperspectral imaging technique: an overview.

    PubMed

    Elmasry, Gamal; Barbin, Douglas F; Sun, Da-Wen; Allen, Paul

    2012-01-01

    During the last two decades, a number of methods have been developed to objectively measure meat quality attributes. Hyperspectral imaging technique as one of these methods has been regarded as a smart and promising analytical tool for analyses conducted in research and industries. Recently there has been a renewed interest in using hyperspectral imaging in quality evaluation of different food products. The main inducement for developing the hyperspectral imaging system is to integrate both spectroscopy and imaging techniques in one system to make direct identification of different components and their spatial distribution in the tested product. By combining spatial and spectral details together, hyperspectral imaging has proved to be a promising technology for objective meat quality evaluation. The literature presented in this paper clearly reveals that hyperspectral imaging approaches have a huge potential for gaining rapid information about the chemical structure and related physical properties of all types of meat. In addition to its ability for effectively quantifying and characterizing quality attributes of some important visual features of meat such as color, quality grade, marbling, maturity, and texture, it is able to measure multiple chemical constituents simultaneously without monotonous sample preparation. Although this technology has not yet been sufficiently exploited in meat process and quality assessment, its potential is promising. Developing a quality evaluation system based on hyperspectral imaging technology to assess the meat quality parameters and to ensure its authentication would bring economical benefits to the meat industry by increasing consumer confidence in the quality of the meat products. This paper provides a detailed overview of the recently developed approaches and latest research efforts exerted in hyperspectral imaging technology developed for evaluating the quality of different meat products and the possibility of its widespread

  11. Image quality assessment by preprocessing and full reference model combination

    NASA Astrophysics Data System (ADS)

    Bianco, S.; Ciocca, G.; Marini, F.; Schettini, R.

    2009-01-01

    This paper focuses on full-reference image quality assessment and presents different computational strategies aimed to improve the robustness and accuracy of some well known and widely used state of the art models, namely the Structural Similarity approach (SSIM) by Wang and Bovik and the S-CIELAB spatial-color model by Zhang and Wandell. We investigate the hypothesis that combining error images with a visual attention model could allow a better fit of the psycho-visual data of the LIVE Image Quality assessment Database Release 2. We show that the proposed quality assessment metric better correlates with the experimental data.

  12. Image quality and breast dose of 24 screen-film combinations for mammography.

    PubMed

    Dimakopoulou, A D; Tsalafoutas, I A; Georgiou, E K; Yakoumakis, E N

    2006-02-01

    In this study the effect of different mammographic screen-film combinations on image quality and breast dose, and the correlation between the various image quality parameters, breast dose and the sensitometric parameters of a film were investigated. Three Agfa (MR5-II, HDR, HT), two Kodak (Min-R M, Min-R 2000), one Fuji (AD-M), one Konica (CM-H) and one Ferrania (HM plus) single emulsion mammographic films were combined with three intensifying screens (Agfa HDS, Kodak Min-R 2190 and Fuji AD-MA). The film characteristics were determined by sensitometry, while the image quality and the dose to the breast of the resulting 24 screen-film combinations were assessed using a mammography quality control phantom. For each combination, three images of the phantom were acquired with optical density within three different ranges. Two observers assessed the quality of the 72 phantom images obtained, while the breast dose was calculated from the exposure data required for each image. Large differences among screen-film combinations in terms of image quality and breast dose were identified however, that, could not be correlated with the film's sensitometric characteristics. All films presented the best resolution when combined with the HDS screen at the expense of speed, and the largest speed when combined with the AD-MA screen, without degradation of the overall image quality. However, an ideal screen-film combination presenting the best image quality with the least dose was not identified. It is also worth mentioning that the best performance for a film was not necessarily obtained when this was combined with the screen provided by the same manufacturer. The results of this study clearly demonstrate that comparison of films based on their sensitometric characteristics are of limited value for clinical practice, as their performance is strongly affected by the screens with which they are combined. PMID:16489193

  13. Method and tool for generating and managing image quality allocations through the design and development process

    NASA Astrophysics Data System (ADS)

    Sparks, Andrew W.; Olson, Craig; Theisen, Michael J.; Addiego, Chris J.; Hutchins, Tiffany G.; Goodman, Timothy D.

    2016-05-01

    Performance models for infrared imaging systems require image quality parameters; optical design engineers need image quality design goals; systems engineers develop image quality allocations to test imaging systems against. It is a challenge to maintain consistency and traceability amongst the various expressions of image quality. We present a method and parametric tool for generating and managing expressions of image quality during the system modeling, requirements specification, design, and testing phases of an imaging system design and development project.

  14. Magnitude of genotype x environment interactions affecting tomato fruit quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    There is a growing interest by consumers to purchase fresh tomato with improved quality traits including lycopene, total soluble solids (TSS), vitamin C and titratable acid (TA) content. Therefore, there are considerable efforts by tomato breeders to improve tomato for these traits. However, suitabl...

  15. Cultural Practices Affect Fruit Quality and Antioxident Capacity in Blueberries

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The effect of cultural practices on fruit quality and antioxidant capacity in highbush blueberries var. Bluecrop was evaluated from random samples of commercial late harvest fields in New Jersey. Results from this single season survey showed that blueberry fruit grown from organic culture yielded hi...

  16. How Do Our Actions Affect Water Quantity and Quality?

    ERIC Educational Resources Information Center

    Gordon, Jessica

    2008-01-01

    Water is an essential resource for all living things. How we live on our watershed can impact water quantity and quality. It is important to recognize how humans alter watershed dynamics, but students often find it challenging to visualize watershed processes and understand how decisions that they make as individuals and together as a community…

  17. Agriculture as a source of Aeolian sediment affecting air quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aeolian processes on agricultural lands have been examined for the past several decades on nearly every continent and has led to a better understanding of detachment, entrainment, transport, and deposition. Relatively little is known concerning the effect of these processes on air quality. In fact, ...

  18. RICE BREAD QUALITY AS AFFECTED BY YEAST AND BRAN

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Whole rice bread (WRB) has been developed in our laboratory for people suffering from Celiac disease and other food allergies. The WRB has texture and related qualities comparable with white or whole wheat breads. This paper reports the results of three levels of yeast, defatted rice bran on the t...

  19. Image quality assessment using Takagi-Sugeno-Kang fuzzy model

    NASA Astrophysics Data System (ADS)

    Äńordević, Dragana; Kukolj, Dragan; Schelkens, Peter

    2015-03-01

    The main aim of the paper is to present a non-linear image quality assessment model based on a fuzzy logic estimator, namely the Takagi-Sugeno-Kang fuzzy model. This image quality assessment model uses a clustered space of input objective metrics. Main advantages of the introduced quality model are simplicity and understandably of its fuzzy rules. As reference model the polynomial 3 rd order model was chosen. The parameters of the Takagi-Sugeno-Kang fuzzy model are optimized in accordance to the mapping criteria of the selected set of input objective quality measures to the Mean Opinion Score (MOS) scale.

  20. Imaging Imageability: Behavioral Effects and Neural Correlates of Its Interaction with Affect and Context.

    PubMed

    Westbury, Chris F; Cribben, Ivor; Cummine, Jacqueline

    2016-01-01

    The construct of imageability refers to the extent to which a word evokes a tangible sensation. Previous research (Westbury et al., 2013) suggests that the behavioral effects attributed to a word's imageability can be largely or wholly explained by two objective constructs, contextual density and estimated affect. Here, we extend these previous findings in two ways. First, we show that closely matched stimuli on the three measures of contextual density, estimated affect, and human-judged imageability show a three-way interaction in explaining variance in LD RTs, but that imagebility accounts for no additional variance after contextual density and estimated affect are entered first. Secondly, we demonstrate that the loci and functional connectivity (via graphical models) of the brain regions implicated in processing the three variables during that task are largely over-lapping and similar. These two lines of evidence support the conclusion that the effect usually attributed to human-judged imageability is largely or entirely due to the effects of other correlated measures that are directly computable. PMID:27471455

  1. Imaging Imageability: Behavioral Effects and Neural Correlates of Its Interaction with Affect and Context

    PubMed Central

    Westbury, Chris F.; Cribben, Ivor; Cummine, Jacqueline

    2016-01-01

    The construct of imageability refers to the extent to which a word evokes a tangible sensation. Previous research (Westbury et al., 2013) suggests that the behavioral effects attributed to a word's imageability can be largely or wholly explained by two objective constructs, contextual density and estimated affect. Here, we extend these previous findings in two ways. First, we show that closely matched stimuli on the three measures of contextual density, estimated affect, and human-judged imageability show a three-way interaction in explaining variance in LD RTs, but that imagebility accounts for no additional variance after contextual density and estimated affect are entered first. Secondly, we demonstrate that the loci and functional connectivity (via graphical models) of the brain regions implicated in processing the three variables during that task are largely over-lapping and similar. These two lines of evidence support the conclusion that the effect usually attributed to human-judged imageability is largely or entirely due to the effects of other correlated measures that are directly computable. PMID:27471455

  2. Objective analysis of image quality of video image capture systems

    NASA Astrophysics Data System (ADS)

    Rowberg, Alan H.

    1990-07-01

    As Picture Archiving and Communication System (PACS) technology has matured, video image capture has become a common way of capturing digital images from many modalities. While digital interfaces, such as those which use the ACR/NEMA standard, will become more common in the future, and are preferred because of the accuracy of image transfer, video image capture will be the dominant method in the short term, and may continue to be used for some time because of the low cost and high speed often associated with such devices. Currently, virtually all installed systems use methods of digitizing the video signal that is produced for display on the scanner viewing console itself. A series of digital test images have been developed for display on either a GE CT9800 or a GE Signa MRI scanner. These images have been captured with each of five commercially available image capture systems, and the resultant images digitally transferred on floppy disk to a PC1286 computer containing Optimast' image analysis software. Here the images can be displayed in a comparative manner for visual evaluation, in addition to being analyzed statistically. Each of the images have been designed to support certain tests, including noise, accuracy, linearity, gray scale range, stability, slew rate, and pixel alignment. These image capture systems vary widely in these characteristics, in addition to the presence or absence of other artifacts, such as shading and moire pattern. Other accessories such as video distribution amplifiers and noise filters can also add or modify artifacts seen in the captured images, often giving unusual results. Each image is described, together with the tests which were performed using them. One image contains alternating black and white lines, each one pixel wide, after equilibration strips ten pixels wide. While some systems have a slew rate fast enough to track this correctly, others blur it to an average shade of gray, and do not resolve the lines, or give

  3. Feature maps driven no-reference image quality prediction of authentically distorted images

    NASA Astrophysics Data System (ADS)

    Ghadiyaram, Deepti; Bovik, Alan C.

    2015-03-01

    Current blind image quality prediction models rely on benchmark databases comprised of singly and synthetically distorted images, thereby learning image features that are only adequate to predict human perceived visual quality on such inauthentic distortions. However, real world images often contain complex mixtures of multiple distortions. Rather than a) discounting the effect of these mixtures of distortions on an image's perceptual quality and considering only the dominant distortion or b) using features that are only proven to be efficient for singly distorted images, we deeply study the natural scene statistics of authentically distorted images, in different color spaces and transform domains. We propose a feature-maps-driven statistical approach which avoids any latent assumptions about the type of distortion(s) contained in an image, and focuses instead on modeling the remarkable consistencies in the scene statistics of real world images in the absence of distortions. We design a deep belief network that takes model-based statistical image features derived from a very large database of authentically distorted images as input and discovers good feature representations by generalizing over different distortion types, mixtures, and severities, which are later used to learn a regressor for quality prediction. We demonstrate the remarkable competence of our features for improving automatic perceptual quality prediction on a benchmark database and on the newly designed LIVE Authentic Image Quality Challenge Database and show that our approach of combining robust statistical features and the deep belief network dramatically outperforms the state-of-the-art.

  4. Interplay between JPEG-2000 image coding and quality estimation

    NASA Astrophysics Data System (ADS)

    Pinto, Guilherme O.; Hemami, Sheila S.

    2013-03-01

    Image quality and utility estimators aspire to quantify the perceptual resemblance and the usefulness of a distorted image when compared to a reference natural image, respectively. Image-coders, such as JPEG-2000, traditionally aspire to allocate the available bits to maximize the perceptual resemblance of the compressed image when compared to a reference uncompressed natural image. Specifically, this can be accomplished by allocating the available bits to minimize the overall distortion, as computed by a given quality estimator. This paper applies five image quality and utility estimators, SSIM, VIF, MSE, NICE and GMSE, within a JPEG-2000 encoder for rate-distortion optimization to obtain new insights on how to improve JPEG-2000 image coding for quality and utility applications, as well as to improve the understanding about the quality and utility estimators used in this work. This work develops a rate-allocation algorithm for arbitrary quality and utility estimators within the Post- Compression Rate-Distortion Optimization (PCRD-opt) framework in JPEG-2000 image coding. Performance of the JPEG-2000 image coder when used with a variety of utility and quality estimators is then assessed. The estimators fall into two broad classes, magnitude-dependent (MSE, GMSE and NICE) and magnitudeindependent (SSIM and VIF). They further differ on their use of the low-frequency image content in computing their estimates. The impact of these computational differences is analyzed across a range of images and bit rates. In general, performance of the JPEG-2000 coder below 1.6 bits/pixel with any of these estimators is highly content dependent, with the most relevant content being the amount of texture in an image and whether the strongest gradients in an image correspond to the main contours of the scene. Above 1.6 bits/pixel, all estimators produce visually equivalent images. As a result, the MSE estimator provides the most consistent performance across all images, while specific

  5. Produce Surface Characteristics Affect Product Quality and Safety

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The surface characteristics of fresh-cut fruits and vegetables vary largely among produce types, maturities and processing procedure. Studies have shown that the surface topography of produce significantly affected adherence, attachment, and biofilm formation of bacteria, as well as their removal a...

  6. Image quality requirements for the digitization of photographic collections

    NASA Astrophysics Data System (ADS)

    Frey, Franziska S.; Suesstrunk, Sabine E.

    1996-02-01

    Managers of photographic collections in libraries and archives are exploring digital image database systems, but they usually have few sources of technical guidance and analysis available. Correctly digitizing photographs puts high demands on the imaging system and the human operators involved in the task. Pictures are very dense with information, requiring high-quality scanning procedures. In order to provide advice to libraries and archives seeking to digitize photographic collections, it is necessary to thoroughly understand the nature of the various originals and the purposes for digitization. Only with this understanding is it possible to choose adequate image quality for the digitization process. The higher the quality, the more expertise, time, and cost is likely to be involved in generating and delivering the image. Despite all the possibilities for endless copying, distributing, and manipulating of digital images, image quality choices made when the files are first created have the same 'finality' that they have in conventional photography. They will have a profound effect on project cost, the value of the final project to researchers, and the usefulness of the images as preservation surrogates. Image quality requirements therefore have to be established carefully before a digitization project starts.

  7. Digital Receptor Image Quality Evaluation: Effect of Different Filtration Schemes

    NASA Astrophysics Data System (ADS)

    Murphy, Simon; Christianson, Olav; Amurao, Maxwell; Samei, Ehsan

    2010-04-01

    The International Electrotechnical Commission provides a standard measurement methodology to provide performance intercomparison between imaging systems. Its formalism specifies beam quality based on half value layer attained by target kVp and additional Al filtration. Similar beam quality may be attained more conveniently using a filtration combination of Cu and Al. This study aimed to compare the two filtration schemes by their effects on image quality in terms of signal-difference-to-noise ratio, spatial resolution, exposure index, noise power spectrum, modulation transfer function, and detective quantum efficiency. A comparative assessment of the images was performed by analyzing commercially available image quality assessment phantom and by following the IEC 62220-3 formalism.

  8. Figure of Image Quality and Information Capacity in Digital Mammography

    PubMed Central

    Michail, Christos M.; Kalyvas, Nektarios E.; Valais, Ioannis G.; Fudos, Ioannis P.; Fountos, George P.; Dimitropoulos, Nikos; Kandarakis, Ioannis S.

    2014-01-01

    Objectives. In this work, a simple technique to assess the image quality characteristics of the postprocessed image is developed and an easy to use figure of image quality (FIQ) is introduced. This FIQ characterizes images in terms of resolution and noise. In addition information capacity, defined within the context of Shannon's information theory, was used as an overall image quality index. Materials and Methods. A digital mammographic image was postprocessed with three digital filters. Resolution and noise were calculated via the Modulation Transfer Function (MTF), the coefficient of variation, and the figure of image quality. In addition, frequency dependent parameters such as the noise power spectrum (NPS) and noise equivalent quanta (NEQ) were estimated and used to assess information capacity. Results. FIQs for the “raw image” data and the image processed with the “sharpen edges” filter were found 907.3 and 1906.1, correspondingly. The information capacity values were 60.86 × 103 and 78.96 × 103 bits/mm2. Conclusion. It was found that, after the application of the postprocessing techniques (even commercial nondedicated software) on the raw digital mammograms, MTF, NPS, and NEQ are improved for medium to high spatial frequencies leading to resolving smaller structures in the final image. PMID:24895593

  9. Factors Affecting Prostate Volume Estimation in Computed Tomography Images

    SciTech Connect

    Yang, Cheng-Hsiu; Wang, Shyh-Jen; Lin, Alex Tong-Long; Lin, Chao-An

    2011-04-01

    The aim of this study was to investigate how apex-localizing methods and the computed tomography (CT) slice thickness affected the CT-based prostate volume estimation. Twenty-eight volunteers underwent evaluations of prostate volume by CT, where the contour segmentations were performed by three observers. The bottom of ischial tuberosities (ITs) and the bulb of the penis were used as reference positions to locate the apex, and the distances to the apex were recorded as 1.3 and 2.0 cm, respectively. Interobserver variations to locate ITs and the bulb of the penis were, on average, 0.10 cm (range 0.03-0.38 cm) and 0.30 cm (range 0.00-0.98 cm), respectively. The range of CT slice thickness varied from 0.08-0.48 cm and was adopted to examine the influence of the variation on volume estimation. The volume deviation from the reference case (0.08 cm), which increases in tandem with the slice thickness, was within {+-} 3 cm{sup 3}, regardless of the adopted apex-locating reference positions. In addition, the maximum error of apex identification was 1.5 times of slice thickness. Finally, based on the precise CT films and the methods of apex identification, there were strong positive correlation coefficients for the estimated prostate volume by CT and the transabdominal ultrasonography, as found in the present study (r > 0.87; p < 0.0001), and this was confirmed by Bland-Altman analysis. These results will help to identify factors that affect prostate volume calculation and to contribute to the improved estimation of the prostate volume based on CT images.

  10. Temporal subtraction in chest radiography: Mutual information as a measure of image quality

    SciTech Connect

    Armato, Samuel G. III; Sensakovic, William F.; Passen, Samantha J.; Engelmann, Roger; MacMahon, Heber

    2009-12-15

    Purpose: Temporal subtraction is used to detect the interval change in chest radiographs and aid radiologists in patient diagnosis. This method registers two temporally different images by geometrically warping the lung region, or ''lung mask,'' of a previous radiographic image to align with the current image. The gray levels of every pixel in the current image are subtracted from the gray levels of the corresponding pixels in the warped previous image to form a temporal subtraction image. While temporal subtraction images effectively enhance areas of pathologic change, misregistration of the images can mislead radiologists by obscuring the interval change or by creating artifacts that mimic change. The purpose of this study was to investigate the utility of mutual information computed between two registered radiographic chest images as a metric for distinguishing between clinically acceptable and clinically unacceptable temporal subtraction images.Methods: A radiologist subjectively rated the image quality of 138 temporal subtraction images using a 1 (poor) to 5 (excellent) scale. To objectively assess the registration accuracy depicted in the temporal subtraction images, which is the main factor that affects the quality of these images, mutual information was computed on the two constituent registered images prior to their subtraction to generate a temporal subtraction image. Mutual information measures the joint entropy of the current image and the warped previous image, yielding a higher value when the gray levels of spatially matched pixels in each image are consistent. Mutual information values were correlated with the radiologist's subjective ratings. To improve this correlation, mutual information was computed from a spatially limited lung mask, which was cropped from the bottom by 10%-60%. Additionally, the number of gray-level values used in the joint entropy histogram was varied. The ability of mutual information to predict the clinical acceptability of

  11. Image quality evaluation and control of computer-generated holograms

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Hiroshi; Yamaguchi, Takeshi; Uetake, Hiroki

    2016-03-01

    Image quality of the computer-generated holograms are usually evaluated subjectively. For example, the re- constructed image from the hologram is compared with other holograms, or evaluated by the double-stimulus impairment scale method to compare with the original image. This paper proposes an objective image quality evaluation of a computer-generated hologram by evaluating both diffraction efficiency and peak signal-to-noise ratio. Theory and numerical experimental results are shown on Fourier transform transmission hologram of both amplitude and phase modulation. Results without the optimized random phase show that the amplitude transmission hologram gives better peak signal-to noise ratio, but the phase transmission hologram provides about 10 times higher diffraction efficiency to the amplitude type. As an optimized phase hologram, Kinoform is evaluated. In addition, we investigate to control image quality by non-linear operation.

  12. Dosimetry and image quality assessment in a direct radiography system

    PubMed Central

    Oliveira, Bruno Beraldo; de Oliveira, Marcio Alves; Paixão, Lucas; Teixeira, Maria Helena Araújo; Nogueira, Maria do Socorro

    2014-01-01

    Objective To evaluate the mean glandular dose with a solid state detector and the image quality in a direct radiography system, utilizing phantoms. Materials and Methods Irradiations were performed with automatic exposure control and polymethyl methacrylate slabs with different thicknesses to calculate glandular dose values. The image quality was evaluated by means of the structures visualized on the images of the phantoms. Results Considering the uncertainty of the measurements, the mean glandular dose results are in agreement with the values provided by the equipment and with internationally adopted reference levels. Results obtained from images of the phantoms were in agreement with the reference values. Conclusion The present study contributes to verify the equipment conformity as regards dose values and image quality. PMID:25741119

  13. Blind noisy image quality evaluation using a deformable ant colony algorithm

    NASA Astrophysics Data System (ADS)

    Chen, Li; Huang, Xiaotong; Tian, Jing; Fu, Xiaowei

    2014-04-01

    The objective of blind noisy image quality assessment is to evaluate the quality of the degraded noisy image without the knowledge of the ground truth image. Its performance relies on the accuracy of the noise statistics estimated from homogenous blocks. The major challenge of block-based approaches lies in the block size selection, as it affects the local noise derivation. To tackle this challenge, a deformable ant colony optimization (DACO) approach is proposed in this paper to adaptively adjust the ant size for image block selection. The proposed DACO approach considers that the size of the ant is adjustable during foraging. For the smooth image blocks, more pheromone is deposited, and then the size of ant is increased. Therefore, this strategy enables the ants to have dynamic food-search capability, leading to more accurate selection of homogeneous blocks. Furthermore, the regression analysis is used to obtain image quality score by exploiting the above-estimated noise statistics. Experimental results are provided to justify that the proposed approach outperforms conventional approaches to provide more accurate noise statistics estimation and achieve a consistent image quality evaluation performance for both the artificially generated and real-world noisy images.

  14. Effect of masking phase-only holograms on the quality of reconstructed images.

    PubMed

    Deng, Yuanbo; Chu, Daping

    2016-04-20

    A phase-only hologram modulates the phase of the incident light and diffracts it efficiently with low energy loss because of the minimum absorption. Much research attention has been focused on how to generate phase-only holograms, and little work has been done to understand the effect and limitation of their partial implementation, possibly due to physical defects and constraints, in particular as in the practical situations where a phase-only hologram is confined or needs to be sliced or tiled. The present study simulates the effect of masking phase-only holograms on the quality of reconstructed images in three different scenarios with different filling factors, filling positions, and illumination intensity profiles. Quantitative analysis confirms that the width of the image point spread function becomes wider and the image quality decreases, as expected, when the filling factor decreases, and the image quality remains the same for different filling positions as well. The width of the image point spread function as derived from different filling factors shows a consistent behavior to that as measured directly from the reconstructed image, especially as the filling factor becomes small. Finally, mask profiles of different shapes and intensity distributions are shown to have more complicated effects on the image point spread function, which in turn affects the quality and textures of the reconstructed image. PMID:27140082

  15. Contrast vs noise effects on image quality

    NASA Astrophysics Data System (ADS)

    Hadar, Ofer; Corse, N.; Rotman, Stanley R.; Kopeika, Norman S.

    1996-11-01

    Low noise images are contract-limited, and image restoration techniques can improve resolution significantly. However, as noise level increases, resolution improvements via image processing become more limited because image restoration increases noise. This research attempts to construct a reliable quantitative means of characterizing the perceptual difference between target and background. A method is suggested for evaluating the extent to which it is possible to discriminate an object which has merged with its surroundings, in noise-limited and contrast limited images, i.e., how hard it would be for an observer to recognize the object against various backgrounds as a function of noise level. The suggested model will be a first order model to begin with, using a regular bar-chart with additive uncorrelated Gaussian noise degraded by standard atmospheric blurring filters. The second phase will comprise a model dealing with higher-order images. This computational model relates the detectability or distinctness of the object to measurable parameters. It also must characterize human perceptual response, i.e. the model must develop metrics which are highly correlated to the ease or difficulty which the human observer experiences in discerning the target from its background. This requirement can be fulfilled only by conducting psychophysical experiments quantitatively comparing the perceptual evaluations of the observers with the results of the mathematical model.

  16. Effects of sparse sampling schemes on image quality in low-dose CT

    SciTech Connect

    Abbas, Sajid; Lee, Taewon; Cho, Seungryong; Shin, Sukyoung; Lee, Rena

    2013-11-15

    Purpose: Various scanning methods and image reconstruction algorithms are actively investigated for low-dose computed tomography (CT) that can potentially reduce a health-risk related to radiation dose. Particularly, compressive-sensing (CS) based algorithms have been successfully developed for reconstructing images from sparsely sampled data. Although these algorithms have shown promises in low-dose CT, it has not been studied how sparse sampling schemes affect image quality in CS-based image reconstruction. In this work, the authors present several sparse-sampling schemes for low-dose CT, quantitatively analyze their data property, and compare effects of the sampling schemes on the image quality.Methods: Data properties of several sampling schemes are analyzed with respect to the CS-based image reconstruction using two measures: sampling density and data incoherence. The authors present five different sparse sampling schemes, and simulated those schemes to achieve a targeted dose reduction. Dose reduction factors of about 75% and 87.5%, compared to a conventional scan, were tested. A fully sampled circular cone-beam CT data set was used as a reference, and sparse sampling has been realized numerically based on the CBCT data.Results: It is found that both sampling density and data incoherence affect the image quality in the CS-based reconstruction. Among the sampling schemes the authors investigated, the sparse-view, many-view undersampling (MVUS)-fine, and MVUS-moving cases have shown promising results. These sampling schemes produced images with similar image quality compared to the reference image and their structure similarity index values were higher than 0.92 in the mouse head scan with 75% dose reduction.Conclusions: The authors found that in CS-based image reconstructions both sampling density and data incoherence affect the image quality, and suggest that a sampling scheme should be devised and optimized by use of these indicators. With this strategic

  17. Objective image quality assessment based on support vector regression.

    PubMed

    Narwaria, Manish; Lin, Weisi

    2010-03-01

    Objective image quality estimation is useful in many visual processing systems, and is difficult to perform in line with the human perception. The challenge lies in formulating effective features and fusing them into a single number to predict the quality score. In this brief, we propose a new approach to address the problem, with the use of singular vectors out of singular value decomposition (SVD) as features for quantifying major structural information in images and then support vector regression (SVR) for automatic prediction of image quality. The feature selection with singular vectors is novel and general for gauging structural changes in images as a good representative of visual quality variations. The use of SVR exploits the advantages of machine learning with the ability to learn complex data patterns for an effective and generalized mapping of features into a desired score, in contrast with the oft-utilized feature pooling process in the existing image quality estimators; this is to overcome the difficulty of model parameter determination for such a system to emulate the related, complex human visual system (HVS) characteristics. Experiments conducted with three independent databases confirm the effectiveness of the proposed system in predicting image quality with better alignment with the HVS's perception than the relevant existing work. The tests with untrained distortions and databases further demonstrate the robustness of the system and the importance of the feature selection. PMID:20100674

  18. Quality of Visual Cue Affects Visual Reweighting in Quiet Standing.

    PubMed

    Moraes, Renato; de Freitas, Paulo Barbosa; Razuk, Milena; Barela, José Angelo

    2016-01-01

    Sensory reweighting is a characteristic of postural control functioning adopted to accommodate environmental changes. The use of mono or binocular cues induces visual reduction/increment of moving room influences on postural sway, suggesting a visual reweighting due to the quality of available sensory cues. Because in our previous study visual conditions were set before each trial, participants could adjust the weight of the different sensory systems in an anticipatory manner based upon the reduction in quality of the visual information. Nevertheless, in daily situations this adjustment is a dynamical process and occurs during ongoing movement. The purpose of this study was to examine the effect of visual transitions in the coupling between visual information and body sway in two different distances from the front wall of a moving room. Eleven young adults stood upright inside of a moving room in two distances (75 and 150 cm) wearing a liquid crystal lenses goggles, which allow individual lenses transition from opaque to transparent and vice-versa. Participants stood still during five minutes for each trial and the lenses status changed every one minute (no vision to binocular vision, no vision to monocular vision, binocular vision to monocular vision, and vice-versa). Results showed that farther distance and monocular vision reduced the effect of visual manipulation on postural sway. The effect of visual transition was condition dependent, with a stronger effect when transitions involved binocular vision than monocular vision. Based upon these results, we conclude that the increased distance from the front wall of the room reduced the effect of visual manipulation on postural sway and that sensory reweighting is stimulus quality dependent, with binocular vision producing a much stronger down/up-weighting than monocular vision. PMID:26939058

  19. Quality of Visual Cue Affects Visual Reweighting in Quiet Standing

    PubMed Central

    Moraes, Renato; de Freitas, Paulo Barbosa; Razuk, Milena; Barela, José Angelo

    2016-01-01

    Sensory reweighting is a characteristic of postural control functioning adopted to accommodate environmental changes. The use of mono or binocular cues induces visual reduction/increment of moving room influences on postural sway, suggesting a visual reweighting due to the quality of available sensory cues. Because in our previous study visual conditions were set before each trial, participants could adjust the weight of the different sensory systems in an anticipatory manner based upon the reduction in quality of the visual information. Nevertheless, in daily situations this adjustment is a dynamical process and occurs during ongoing movement. The purpose of this study was to examine the effect of visual transitions in the coupling between visual information and body sway in two different distances from the front wall of a moving room. Eleven young adults stood upright inside of a moving room in two distances (75 and 150 cm) wearing a liquid crystal lenses goggles, which allow individual lenses transition from opaque to transparent and vice-versa. Participants stood still during five minutes for each trial and the lenses status changed every one minute (no vision to binocular vision, no vision to monocular vision, binocular vision to monocular vision, and vice-versa). Results showed that farther distance and monocular vision reduced the effect of visual manipulation on postural sway. The effect of visual transition was condition dependent, with a stronger effect when transitions involved binocular vision than monocular vision. Based upon these results, we conclude that the increased distance from the front wall of the room reduced the effect of visual manipulation on postural sway and that sensory reweighting is stimulus quality dependent, with binocular vision producing a much stronger down/up-weighting than monocular vision. PMID:26939058

  20. Imaging quality full chip verification for yield improvement

    NASA Astrophysics Data System (ADS)

    Yang, Qing; Zhou, CongShu; Quek, ShyueFong; Lu, Mark; Foong, YeeMei; Qiu, JianHong; Pandey, Taksh; Dover, Russell

    2013-04-01

    Basic image intensity parameters, like maximum and minimum intensity values (Imin and Imax), image logarithm slope (ILS), normalized image logarithm slope (NILS) and mask error enhancement factor (MEEF) , are well known as indexes of photolithography imaging quality. For full chip verification, hotspot detection is typically based on threshold values for line pinching or bridging. For image intensity parameters it is generally harder to quantify an absolute value to define where the process limit will occur, and at which process stage; lithography, etch or post- CMP. However it is easy to conclude that hot spots captured by image intensity parameters are more susceptible to process variation and very likely to impact yield. In addition these image intensity hot spots can be missed by using resist model verification because the resist model normally is calibrated by the wafer data on a single resist plane and is an empirical model which is trying to fit the resist critical dimension by some mathematic algorithm with combining optical calculation. Also at resolution enhancement technology (RET) development stage, full chip imaging quality check is also a method to qualify RET solution, like Optical Proximity Correct (OPC) performance. To add full chip verification using image intensity parameters is also not as costly as adding one more resist model simulation. From a foundry yield improvement and cost saving perspective, it is valuable to quantify the imaging quality to find design hot spots to correctly define the inline process control margin. This paper studies the correlation between image intensity parameters and process weakness or catastrophic hard failures at different process stages. It also demonstrated how OPC solution can improve full chip image intensity parameters. Rigorous 3D resist profile simulation across the full height of the resist stack was also performed to identify a correlation to the image intensity parameter. A methodology of post-OPC full

  1. Does Aggregation Affect the Redistribution and Quality of Eroded SOC?

    NASA Astrophysics Data System (ADS)

    Hu, Yaxian; Kuhn, Nikolaus

    2015-04-01

    A substantial amount of literature has discussed the impacts of soil erosion on global carbon cycling. However, numerous gaps in our knowledge remain unaddressed, for instance, the biogeochemical fate of displaced SOC during transport being one of them. The transport distance and the quality of eroded SOC are the two major factors that determine its fate. Previous laboratory-based research had demonstrated that the effects of aggregation can potentially shorten the transport distance of eroded SOC. The mineralization potential of SOC also differs in sediment fractions of different likely transport distances. It is therefore essential to examine the transport distance and quality of eroded SOC under field conditions with natural rainfall as the agent of erosion. Soil samples from a silty clay soil from Switzerland and a sandy soil from Denmark, were collected in the field this summer after natural rainfall events. The soil from Switzerland was sampled from a field of maize in St. Ursanne (47°20' N 7°09' E) on August 6th, 2014 after a natural rainfall event. A depositional fan consisting of aggregated sediment was formed outside the lower edge of the field. The sandy soil from Denmark was sampled from a farm in Foulum (56°30' N, 9°35' W) on September 4, 2014, after a series of natural rainfall events. Soil samples were collected at different topographic positions along the two slopes. All the soil samples from the two farms were fractionated by a settling tube. Bulk soil from Switzerland and Denmark was also dispersed by ultrasound. The SOC contents of all bulk soils and associated fractions were determined using a carbon analyzer Leco 612 at 1000°C. The quality of SOC in different settling fractions collected from various topographic positions were also determined by stable isotopes of C and N (13C and 15N). Our results show that 1) the aggregate specific SOC distribution evidently differs from the mineral particle specific SOC distribution, indicating that re

  2. Applying image quality in cell phone cameras: lens distortion

    NASA Astrophysics Data System (ADS)

    Baxter, Donald; Goma, Sergio R.; Aleksic, Milivoje

    2009-01-01

    This paper describes the framework used in one of the pilot studies run under the I3A CPIQ initiative to quantify overall image quality in cell-phone cameras. The framework is based on a multivariate formalism which tries to predict overall image quality from individual image quality attributes and was validated in a CPIQ pilot program. The pilot study focuses on image quality distortions introduced in the optical path of a cell-phone camera, which may or may not be corrected in the image processing path. The assumption is that the captured image used is JPEG compressed and the cellphone camera is set to 'auto' mode. As the used framework requires that the individual attributes to be relatively perceptually orthogonal, in the pilot study, the attributes used are lens geometric distortion (LGD) and lateral chromatic aberrations (LCA). The goal of this paper is to present the framework of this pilot project starting with the definition of the individual attributes, up to their quantification in JNDs of quality, a requirement of the multivariate formalism, therefore both objective and subjective evaluations were used. A major distinction in the objective part from the 'DSC imaging world' is that the LCA/LGD distortions found in cell-phone cameras, rarely exhibit radial behavior, therefore a radial mapping/modeling cannot be used in this case.

  3. Subjective image quality comparison between two digital dental radiographic systems and conventional dental film

    PubMed Central

    Ajmal, Muhammed; Elshinawy, Mohamed I.

    2014-01-01

    Objectives Digital radiography has become an integral part of dentistry. Digital radiography does not require film or dark rooms, reduces X-ray doses, and instantly generates images. The aim of our study was to compare the subjective image quality of two digital dental radiographic systems with conventional dental film. Materials & methods A direct digital (DD) ‘Digital’ system by Sirona, a semi-direct (SD) digital system by Vista-scan, and Kodak ‘E’ speed dental X-ray films were selected for the study. Endodontically-treated extracted teeth (n = 25) were used in the study. Details of enamel, dentin, dentino-enamel junction, root canal filling (gutta percha), and simulated apical pathology were investigated with the three radiographic systems. The data were subjected to statistical analyzes to reveal differences in subjective image quality. Results Conventional dental X-ray film was superior to the digital systems. For digital systems, DD imaging was superior to SD imaging. Conclusion Conventional film yielded superior image quality that was statistically significant in almost all aspects of comparison. Conventional film was followed in image quality by DD, and SD provided the lowest quality images. Conventional film is still considered the gold standard to diagnose diseases affecting the jawbone. Recommendations Improved software and hardware for digital imaging systems are now available and these improvements may now yield images that are comparable in quality to conventional film. However, we recommend that studies still use more observers and other statistical methods to produce ideal results. PMID:25382946

  4. Refractive Errors Affect the Vividness of Visual Mental Images

    PubMed Central

    Palermo, Liana; Nori, Raffaella; Piccardi, Laura; Zeri, Fabrizio; Babino, Antonio; Giusberti, Fiorella; Guariglia, Cecilia

    2013-01-01

    The hypothesis that visual perception and mental imagery are equivalent has never been explored in individuals with vision defects not preventing the visual perception of the world, such as refractive errors. Refractive error (i.e., myopia, hyperopia or astigmatism) is a condition where the refracting system of the eye fails to focus objects sharply on the retina. As a consequence refractive errors cause blurred vision. We subdivided 84 individuals according to their spherical equivalent refraction into Emmetropes (control individuals without refractive errors) and Ametropes (individuals with refractive errors). Participants performed a vividness task and completed a questionnaire that explored their cognitive style of thinking before their vision was checked by an ophthalmologist. Although results showed that Ametropes had less vivid mental images than Emmetropes this did not affect the development of their cognitive style of thinking; in fact, Ametropes were able to use both verbal and visual strategies to acquire and retrieve information. Present data are consistent with the hypothesis of equivalence between imagery and perception. PMID:23755186

  5. Improvement of integral 3D image quality by compensating for lens position errors

    NASA Astrophysics Data System (ADS)

    Okui, Makoto; Arai, Jun; Kobayashi, Masaki; Okano, Fumio

    2004-05-01

    Integral photography (IP) or integral imaging is a way to create natural-looking three-dimensional (3-D) images with full parallax. Integral three-dimensional television (integral 3-D TV) uses a method that electronically presents 3-D images in real time based on this IP method. The key component is a lens array comprising many micro-lenses for shooting and displaying. We have developed a prototype device with about 18,000 lenses using a super-high-definition camera with 2,000 scanning lines. Positional errors of these high-precision lenses as well as the camera's lenses will cause distortions in the elemental image, which directly affect the quality of the 3-D image and the viewing area. We have devised a way to compensate for such geometrical position errors and used it for the integral 3-D TV prototype, resulting in an improvement in both viewing zone and picture quality.

  6. Determinants of image quality of rotational angiography for on-line assessment of frame geometry after transcatheter aortic valve implantation.

    PubMed

    Rodríguez-Olivares, Ramón; El Faquir, Nahid; Rahhab, Zouhair; Maugenest, Anne-Marie; Van Mieghem, Nicolas M; Schultz, Carl; Lauritsch, Guenter; de Jaegere, Peter P T

    2016-07-01

    To study the determinants of image quality of rotational angiography using dedicated research prototype software for motion compensation without rapid ventricular pacing after the implantation of four commercially available catheter-based valves. Prospective observational study including 179 consecutive patients who underwent transcatheter aortic valve implantation (TAVI) with either the Medtronic CoreValve (MCS), Edward-SAPIEN Valve (ESV), Boston Sadra Lotus (BSL) or Saint-Jude Portico Valve (SJP) in whom rotational angiography (R-angio) with motion compensation 3D image reconstruction was performed. Image quality was evaluated from grade 1 (excellent image quality) to grade 5 (strongly degraded). Distinction was made between good (grades 1, 2) and poor image quality (grades 3-5). Clinical (gender, body mass index, Agatston score, heart rate and rhythm, artifacts), procedural (valve type) and technical variables (isocentricity) were related with the image quality assessment. Image quality was good in 128 (72 %) and poor in 51 (28 %) patients. By univariable analysis only valve type (BSL) and the presence of an artefact negatively affected image quality. By multivariate analysis (in which BMI was forced into the model) BSL valve (Odds 3.5, 95 % CI [1.3-9.6], p = 0.02), presence of an artifact (Odds 2.5, 95 % CI [1.2-5.4], p = 0.02) and BMI (Odds 1.1, 95 % CI [1.0-1.2], p = 0.04) were independent predictors of poor image quality. Rotational angiography with motion compensation 3D image reconstruction using a dedicated research prototype software offers good image quality for the evaluation of frame geometry after TAVI in the majority of patients. Valve type, presence of artifacts and higher BMI negatively affect image quality. PMID:27139459

  7. Wind resource quality affected by high levels of renewables

    DOE PAGESBeta

    Diakov, Victor

    2015-06-17

    For solar photovoltaic (PV) and wind resources, the capacity factor is an important parameter describing the quality of the resource. As the share of variable renewable resources (such as PV and wind) on the electric system is increasing, so does curtailment (and the fraction of time when it cannot be avoided). At high levels of renewable generation, curtailments effectively change the practical measure of resource quality from capacity factor to the incremental capacity factor. The latter accounts only for generation during hours of no curtailment and is directly connected with the marginal capital cost of renewable generators for a givenmore » level of renewable generation during the year. The Western U.S. wind generation is analyzed hourly for a system with 75% of annual generation from wind, and it is found that the value for the system of resources with equal capacity factors can vary by a factor of 2, which highlights the importance of using the incremental capacity factor instead. Finally, the effect is expected to be more pronounced in smaller geographic areas (or when transmission limitations imposed) and less pronounced at lower levels of renewable energy in the system with less curtailment.« less

  8. Regimen of ovarian stimulation affects oocyte and therefore embryo quality.

    PubMed

    Bosch, Ernesto; Labarta, Elena; Kolibianakis, Efstratios; Rosen, Mitchell; Meldrum, David

    2016-03-01

    Without any doubt the regimen used to mature multiple capable oocytes for IVF impacts IVF outcomes. Studies have indicated that the inclusion of LH activity, adjuvant agents such as growth hormone (GH), and regimens providing for simultaneous action of both LH and FSH during final oocyte maturation may have beneficial effects on IVF outcomes. Because of the difficulty in improving IVF outcomes in poor responders, the studies on GH are of particular interest. As pointed out in this review, the apparent beneficial effects of GH on oocyte competence may also apply to older women or to normal responders with reduced embryo quality. A much more difficult question is whether and how much ovarian stimulation impacts on oocyte competence. Paradoxically it seems that there are not demonstrated differences between the stimulated and the natural unstimulated cycle, whereas studies in laboratory animals and IVF patients have shown deleterious effects of higher compared with lower doses of gonadotropins. Recent studies suggest that the use of high doses of gonadotropins as an independent factor correlates negatively with the probability of live birth, whereas a high ovarian response per se is associated with better cumulative pregnancy rates, owing to the availability of more euploid and good-quality embryos. Although adjunctive use of androgens has not been discussed here, it is briefly covered in the first review of this series. PMID:26826273

  9. Wind resource quality affected by high levels of renewables

    SciTech Connect

    Diakov, Victor

    2015-06-17

    For solar photovoltaic (PV) and wind resources, the capacity factor is an important parameter describing the quality of the resource. As the share of variable renewable resources (such as PV and wind) on the electric system is increasing, so does curtailment (and the fraction of time when it cannot be avoided). At high levels of renewable generation, curtailments effectively change the practical measure of resource quality from capacity factor to the incremental capacity factor. The latter accounts only for generation during hours of no curtailment and is directly connected with the marginal capital cost of renewable generators for a given level of renewable generation during the year. The Western U.S. wind generation is analyzed hourly for a system with 75% of annual generation from wind, and it is found that the value for the system of resources with equal capacity factors can vary by a factor of 2, which highlights the importance of using the incremental capacity factor instead. Finally, the effect is expected to be more pronounced in smaller geographic areas (or when transmission limitations imposed) and less pronounced at lower levels of renewable energy in the system with less curtailment.

  10. Image quality based x-ray dose control in cardiac imaging

    NASA Astrophysics Data System (ADS)

    Davies, Andrew G.; Kengyelics, Stephen M.; Gislason-Lee, Amber J.

    2015-03-01

    An automated closed-loop dose control system balances the radiation dose delivered to patients and the quality of images produced in cardiac x-ray imaging systems. Using computer simulations, this study compared two designs of automatic x-ray dose control in terms of the radiation dose and quality of images produced. The first design, commonly in x-ray systems today, maintained a constant dose rate at the image receptor. The second design maintained a constant image quality in the output images. A computer model represented patients as a polymethylmetacrylate phantom (which has similar x-ray attenuation to soft tissue), containing a detail representative of an artery filled with contrast medium. The model predicted the entrance surface dose to the phantom and contrast to noise ratio of the detail as an index of image quality. Results showed that for the constant dose control system, phantom dose increased substantially with phantom size (x5 increase between 20 cm and 30 cm thick phantom), yet the image quality decreased by 43% for the same thicknesses. For the constant quality control, phantom dose increased at a greater rate with phantom thickness (>x10 increase between 20 cm and 30 cm phantom). Image quality based dose control could tailor the x-ray output to just achieve the quality required, which would reduce dose to patients where the current dose control produces images of too high quality. However, maintaining higher levels of image quality for large patients would result in a significant dose increase over current practice.

  11. Raman chemical imaging technology for food safety and quality evaluation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Raman chemical imaging combines Raman spectroscopy and digital imaging to visualize composition and morphology of a target. This technique offers great potential for food safety and quality research. Most commercial Raman instruments perform measurement at microscopic level, and the spatial range ca...

  12. A feature-enriched completely blind image quality evaluator.

    PubMed

    Lin Zhang; Lei Zhang; Bovik, Alan C

    2015-08-01

    Existing blind image quality assessment (BIQA) methods are mostly opinion-aware. They learn regression models from training images with associated human subjective scores to predict the perceptual quality of test images. Such opinion-aware methods, however, require a large amount of training samples with associated human subjective scores and of a variety of distortion types. The BIQA models learned by opinion-aware methods often have weak generalization capability, hereby limiting their usability in practice. By comparison, opinion-unaware methods do not need human subjective scores for training, and thus have greater potential for good generalization capability. Unfortunately, thus far no opinion-unaware BIQA method has shown consistently better quality prediction accuracy than the opinion-aware methods. Here, we aim to develop an opinion-unaware BIQA method that can compete with, and perhaps outperform, the existing opinion-aware methods. By integrating the features of natural image statistics derived from multiple cues, we learn a multivariate Gaussian model of image patches from a collection of pristine natural images. Using the learned multivariate Gaussian model, a Bhattacharyya-like distance is used to measure the quality of each image patch, and then an overall quality score is obtained by average pooling. The proposed BIQA method does not need any distorted sample images nor subjective quality scores for training, yet extensive experiments demonstrate its superior quality-prediction performance to the state-of-the-art opinion-aware BIQA methods. The MATLAB source code of our algorithm is publicly available at www.comp.polyu.edu.hk/~cslzhang/IQA/ILNIQE/ILNIQE.htm. PMID:25915960

  13. A patient image-based technique to assess the image quality of clinical chest radiographs

    NASA Astrophysics Data System (ADS)

    Lin, Yuan; Samei, Ehsan; Luo, Hui; Dobbins, James T., III; McAdams, H. Page; Wang, Xiaohui; Sehnert, William J.; Barski, Lori; Foos, David H.

    2011-03-01

    Current clinical image quality assessment techniques mainly analyze image quality for the imaging system in terms of factors such as the capture system DQE and MTF, the exposure technique, and the particular image processing method and processing parameters. However, when assessing a clinical image, radiologists seldom refer to these factors, but rather examine several specific regions of the image to see whether the image is suitable for diagnosis. In this work, we developed a new strategy to learn and simulate radiologists' evaluation process on actual clinical chest images. Based on this strategy, a preliminary study was conducted on 254 digital chest radiographs (38 AP without grids, 35 AP with 6:1 ratio grids and 151 PA with 10:1 ratio grids). First, ten regional based perceptual qualities were summarized through an observer study. Each quality was characterized in terms of a physical quantity measured from the image, and as a first step, the three physical quantities in lung region were then implemented algorithmically. A pilot observer study was performed to verify the correlation between image perceptual qualities and physical quantitative qualities. The results demonstrated that our regional based metrics have promising performance for grading perceptual properties of chest radiographs.

  14. Image forgery detection by means of no-reference quality metrics

    NASA Astrophysics Data System (ADS)

    Battisti, F.; Carli, M.; Neri, A.

    2012-03-01

    In this paper a methodology for digital image forgery detection by means of an unconventional use of image quality assessment is addressed. In particular, the presence of differences in quality degradations impairing the images is adopted to reveal the mixture of different source patches. The ratio behind this work is in the hypothesis that any image may be affected by artifacts, visible or not, caused by the processing steps: acquisition (i.e., lens distortion, acquisition sensors imperfections, analog to digital conversion, single sensor to color pattern interpolation), processing (i.e., quantization, storing, jpeg compression, sharpening, deblurring, enhancement), and rendering (i.e., image decoding, color/size adjustment). These defects are generally spatially localized and their strength strictly depends on the content. For these reasons they can be considered as a fingerprint of each digital image. The proposed approach relies on a combination of image quality assessment systems. The adopted no-reference metric does not require any information about the original image, thus allowing an efficient and stand-alone blind system for image forgery detection. The experimental results show the effectiveness of the proposed scheme.

  15. Domestic cooking methods affect the nutritional quality of red cabbage.

    PubMed

    Xu, Feng; Zheng, Yonghua; Yang, Zhenfeng; Cao, Shifeng; Shao, Xingfeng; Wang, Hongfei

    2014-10-15

    The aim of this work is to investigate the effects of domestic cooking methods, including steaming, microwave heating, boiling and stir-frying on the nutritional quality of red cabbage. Compared with fresh-cut red cabbage, all cooking methods were found to cause significant reduction in anthocyanin and total glucosinolates contents. Moreover, steaming resulted in significantly greater retention of vitamin C and DPPH radical-scavenging activity, while stir-frying and boiling, two popular Chinese cooking methods, led to significant losses of total phenolic, vitamin C, DPPH radical-scavenging activity, and total soluble sugar as well as reducing sugars. Normally, red cabbage consumed fresh in salads could maintain the highest nutrition. However, considering the habits of Asian cuisine, it is recommended to use less water and less cooking time, such as steaming based on our present results, so as to retain the optimum benefits of the health-promoting compounds. PMID:24837935

  16. Image integrity and aesthetics: towards a more encompassing definition of visual quality

    NASA Astrophysics Data System (ADS)

    Redi, Judith A.; Heynderickx, Ingrid

    2012-03-01

    Visual quality is a multifaceted quantity that depends on multiple attributes of the image/video. According to Keelan's definition, artifactual attributes concern features of the image that when visible, are annoying and compromise the integrity of the image. Aesthetic attributes instead depend on the observer's personal taste. Both types of attributes have been studied in the literature in relation to visual quality, but never in conjunction with each other. In this paper we perform a psychometric experiment to investigate how artifactual and aesthetic attributes interact, and how they affect the viewing behavior. In particular, we studied to what extent the appearance of artifacts impacts the aesthetic quality of images. Our results indicate that indeed image integrity somehow influences the aesthetic quality scores. By means of an eye-tracker, we also recorded and analyzed the viewing behavior of our participants while scoring aesthetic quality. Results reveal that, when scoring aesthetic quality, viewing behavior significantly departs from the natural free looking, as well as from the viewing behavior observed for integrity scoring.

  17. Image Quality Evalutation on ALOS/PRISM and AVNIR-2

    NASA Astrophysics Data System (ADS)

    Mukaida, Akira; Imoto, Naritoshi; Tadono, Takeo; Murakami, Hiroshi; Kawamoto, Sachi

    2008-11-01

    Image quality evaluation on ALOS (Advanced Land Observing Satellite) / PRISM (Panchromatic Remote-sensing Instrument for Stereo Mapping) and AVNIR-2 (Advanced Visible and Near Infrared Radiometer 2) has been carried out during operational phase. This is a report on result of evaluation for image quality in terms of MTF (Modulation Transfer Function) and SNR (Signal to Noise Ratio) for both PRISM and AVNIR-2. SNR of PRISM image has been increased following the up dating of radiometric correction and implementation of JPEG noise reduction filter. The result was in range of specification for both sensors.

  18. Effect of optical aberrations on image quality and visual performance

    NASA Astrophysics Data System (ADS)

    Ravikumar, Sowmya

    In addition to the effects of diffraction, retinal image quality in the human eye is degraded by optical aberrations. Although the paraxial geometric optics description of defocus consists of a simple blurred circle whose size determines the extent of blur, in reality the interactions between monochromatic and chromatic aberrations create a complex pattern of retinal image degradation. My thesis work hypothesizes that although both monochromatic and chromatic optical aberrations in general reduce image quality from best achievable, the underlying causes of retinal image quality degradation are characteristic of the nature of the aberration, its interactions with other aberrations as well as the composition of the stimulus. To establish a controlled methodology, a computational model of the retinal image with various levels of aberrations was used to create filters equivalent to those produced by real optical aberrations. Visual performance was measured psychophysically by using these special filters that separately modulated amplitude and phase in the retinal image. In order to include chromatic aberration into the optical interactions, a computational polychromatic model of the eye was created and validated. The model starts with monochromatic wavefront maps and derives a composite white light point-spread function whose quality was assessed using metrics of image quality. Finally, in order to assess the effectiveness of simultaneous multifocal intra-ocular lenses in correcting the eye's optical aberrations, a polychromatic computational model of a pseudophakic eye was constructed. This model incorporated the special chromatic properties unique to an eye corrected with hybrid refractive-diffractive optical elements. Results showed that normal optical aberrations reduced visual performance not only by reducing image contrast but also by altering the phase structure of the image. Longitudinal chromatic aberration had a greater effect on image quality in isolation

  19. Digital image quality measurements by objective and subjective methods from series of parametrically degraded images

    NASA Astrophysics Data System (ADS)

    Tachó, Aura; Mitjà, Carles; Martínez, Bea; Escofet, Jaume; Ralló, Miquel

    2013-11-01

    Many digital image applications like digitization of cultural heritage for preservation purposes operate with compressed files in one or more image observing steps. For this kind of applications JPEG compression is one of the most widely used. Compression level, final file size and quality loss are parameters that must be managed optimally. Although this loss can be monitored by means of objective image quality measurements, the real challenge is to know how it can be related with the perceived image quality by observers. A pictorial image has been degraded by two different procedures. The first, applying different levels of low pass filtering by convolving the image with progressively broad Gauss kernels. The second, saving the original file to a series of JPEG compression levels. In both cases, the objective image quality measurement is done by analysis of the image power spectrum. In order to obtain a measure of the perceived image quality, both series of degraded images are displayed on a computer screen organized in random pairs. The observers are compelled to choose the best image of each pair. Finally, a ranking is established applying Thurstone scaling method. Results obtained by both measurements are compared between them and with other objective measurement method as the Slanted Edge Test.

  20. Total Quality Can Help Your District's Image.

    ERIC Educational Resources Information Center

    Cokeley, Sandra

    1996-01-01

    Describes how educators in the Pearl River School District, Pearl River, New York, have implemented Total Quality Management (TQM) principles to evaluate and improve their effectiveness. Includes two charts that depict key indicators of financial and academic performance and a seven-year profile of the district's budget, enrollment, diploma rate,…

  1. Optimization and image quality assessment of the alpha-image reconstruction algorithm: iterative reconstruction with well-defined image quality metrics

    NASA Astrophysics Data System (ADS)

    Lebedev, Sergej; Sawall, Stefan; Kuchenbecker, Stefan; Faby, Sebastian; Knaup, Michael; Kachelrieß, Marc

    2015-03-01

    The reconstruction of CT images with low noise and highest spatial resolution is a challenging task. Usually, a trade-off between at least these two demands has to be found or several reconstructions with mutually exclusive properties, i.e. either low noise or high spatial resolution, have to be performed. Iterative reconstruction methods might be suitable tools to overcome these limitations and provide images of highest diagnostic quality with formerly mutually exclusive image properties. While image quality metrics like the modulation transfer function (MTF) or the point spread function (PSF) are well-defined in case of standard reconstructions, e.g. filtered backprojection, the iterative algorithms lack these metrics. To overcome this issue alternate methodologies like the model observers have been proposed recently to allow a quantification of a usually task-dependent image quality metric.1 As an alternative we recently proposed an iterative reconstruction method, the alpha-image reconstruction (AIR), providing well-defined image quality metrics on a per-voxel basis.2 In particular, the AIR algorithm seeks to find weighting images, the alpha-images, that are used to blend between basis images with mutually exclusive image properties. The result is an image with highest diagnostic quality that provides a high spatial resolution and a low noise level. As the estimation of the alpha-images is computationally demanding we herein aim at optimizing this process and highlight the favorable properties of AIR using patient measurements.

  2. Reduced Height (Rht) Alleles Affect Wheat Grain Quality

    PubMed Central

    Casebow, Richard; Hadley, Caroline; Uppal, Rajneet; Addisu, Molla; Loddo, Stefano; Kowalski, Ania; Griffiths, Simon; Gooding, Mike

    2016-01-01

    The effects of dwarfing alleles (reduced height, Rht) in near isogenic lines on wheat grain quality are characterised in field experiments and related to effects on crop height, grain yield and GA-sensitivity. Alleles included those that conferred GA-insensitivity (Rht-B1b, Rht-B1c, Rht-D1b, Rht-D1c) as well as those that retained GA-sensitivity (rht(tall), Rht8, Rht8 + Ppd-D1a, Rht12). Full characterisation was facilitated by including factors with which the effects of Rht alleles are known to interact for grain yield (i.e. system, [conventional or organic]; tillage intensity [plough-based, minimum or zero]; nitrogen fertilizer level [0–450 kg N/ha]; and genetic backgrounds varying in height [cvs Maris Huntsman, Maris Widgeon, and Mercia]. Allele effects on mean grain weight and grain specific weight were positively associated with final crop height: dwarfing reduced these quality criteria irrespective of crop management or GA-sensitivity. In all but two experiments the effects of dwarfing alleles on grain nitrogen and sulphur concentrations were closely and negatively related to effects on grain yield, e.g. a quadratic relationship between grain yield and crop height manipulated by the GA-insensitive alleles was mirrored by quadratic relationships for nitrogen and sulphur concentrations: the highest yields and most dilute concentrations occurred around 80cm. In one of the two exceptional experiments the GA-insensitive Rht-B1b and Rht-B1c significantly (P<0.05) reduced grain nitrogen concentration in the absence of an effect on yield, and in the remaining experiment the GA-sensitive Rht8 significantly reduced both grain yield and grain nitrogen concentration simultaneously. When Rht alleles diluted grain nitrogen concentration, N:S ratios and SDS-sedimentation volumes were often improved. Hagberg falling number (HFN) was negatively related to crop height but benefits from dwarfing were only seen for GA-insensitive alleles. For HFN, therefore, there was the

  3. Reduced Height (Rht) Alleles Affect Wheat Grain Quality.

    PubMed

    Casebow, Richard; Hadley, Caroline; Uppal, Rajneet; Addisu, Molla; Loddo, Stefano; Kowalski, Ania; Griffiths, Simon; Gooding, Mike

    2016-01-01

    The effects of dwarfing alleles (reduced height, Rht) in near isogenic lines on wheat grain quality are characterised in field experiments and related to effects on crop height, grain yield and GA-sensitivity. Alleles included those that conferred GA-insensitivity (Rht-B1b, Rht-B1c, Rht-D1b, Rht-D1c) as well as those that retained GA-sensitivity (rht(tall), Rht8, Rht8 + Ppd-D1a, Rht12). Full characterisation was facilitated by including factors with which the effects of Rht alleles are known to interact for grain yield (i.e. system, [conventional or organic]; tillage intensity [plough-based, minimum or zero]; nitrogen fertilizer level [0-450 kg N/ha]; and genetic backgrounds varying in height [cvs Maris Huntsman, Maris Widgeon, and Mercia]. Allele effects on mean grain weight and grain specific weight were positively associated with final crop height: dwarfing reduced these quality criteria irrespective of crop management or GA-sensitivity. In all but two experiments the effects of dwarfing alleles on grain nitrogen and sulphur concentrations were closely and negatively related to effects on grain yield, e.g. a quadratic relationship between grain yield and crop height manipulated by the GA-insensitive alleles was mirrored by quadratic relationships for nitrogen and sulphur concentrations: the highest yields and most dilute concentrations occurred around 80cm. In one of the two exceptional experiments the GA-insensitive Rht-B1b and Rht-B1c significantly (P<0.05) reduced grain nitrogen concentration in the absence of an effect on yield, and in the remaining experiment the GA-sensitive Rht8 significantly reduced both grain yield and grain nitrogen concentration simultaneously. When Rht alleles diluted grain nitrogen concentration, N:S ratios and SDS-sedimentation volumes were often improved. Hagberg falling number (HFN) was negatively related to crop height but benefits from dwarfing were only seen for GA-insensitive alleles. For HFN, therefore, there was the

  4. Study of a water quality imager for coastal zone missions

    NASA Technical Reports Server (NTRS)

    Staylor, W. F.; Harrison, E. F.; Wessel, V. W.

    1975-01-01

    The present work surveys water quality user requirements and then determines the general characteristics of an orbiting imager (the Applications Explorer, or AE) dedicated to the measurement of water quality, which could be used as a low-cost means of testing advanced imager concepts and assessing the ability of imager techniques to meet the goals of a comprehensive water quality monitoring program. The proposed imager has four spectral bands, a spatial resolution of 25 meters, and swath width of 36 km with a pointing capability of 330 km. Silicon photodetector arrays, pointing systems, and several optical features are included. A nominal orbit of 500 km altitude at an inclination of 50 deg is recommended.

  5. Quality evaluation of extra high quality images based on key assessment word

    NASA Astrophysics Data System (ADS)

    Kameda, Masashi; Hayashi, Hidehiko; Akamatsu, Shigeru; Miyahara, Makoto M.

    2001-06-01

    An all encompassing goal of our research is to develop an extra high quality imaging system which is able to convey a high level artistic impression faithfully. We have defined a high order sensation as such a high level artistic impression, and it is supposed that the high order sensation is expressed by the combination of the psychological factor which can be described by plural assessment words. In order to pursue the quality factors that are important for the reproduction of the high order sensation, we have focused on the image quality evaluation of the extra high quality images using the assessment words considering the high order sensation. In this paper, we have obtained the hierarchical structure between the collected assessment words and the principles of European painting based on the conveyance model of the high order sensation, and we have determined a key assessment word 'plasticity' which is able to evaluate the reproduction of the high order sensation more accurately. The results of the subjective assessment experiments using the prototype of the developed extra high quality imaging system have shown that the obtained key assessment word 'plasticity' is the most appropriate assessment word to evaluate the image quality of the extra high quality images quasi-quantitatively.

  6. Imaging quality assessment of multi-modal miniature microscope.

    PubMed

    Lee, Junwon; Rogers, Jeremy; Descour, Michael; Hsu, Elizabeth; Aaron, Jesse; Sokolov, Konstantin; Richards-Kortum, Rebecca

    2003-06-16

    We are developing a multi-modal miniature microscope (4M device) to image morphology and cytochemistry in vivo and provide better delineation of tumors. The 4M device is designed to be a complete microscope on a chip, including optical, micro-mechanical, and electronic components. It has advantages such as compact size and capability for microscopic-scale imaging. This paper presents an optics-only prototype 4M device, the very first imaging system made of sol-gel material. The microoptics used in the 4M device has a diameter of 1.3 mm. Metrology of the imaging quality assessment of the prototype device is presented. We describe causes of imaging performance degradation in order to improve the fabrication process. We built a multi-modal imaging test-bed to measure first-order properties and to assess the imaging quality of the 4M device. The 4M prototype has a field of view of 290 microm in diameter, a magnification of -3.9, a working distance of 250 microm and a depth of field of 29.6+/-6 microm. We report the modulation transfer function (MTF) of the 4M device as a quantitative metric of imaging quality. Based on the MTF data, we calculated a Strehl ratio of 0.59. In order to investigate the cause of imaging quality degradation, the surface characterization of lenses in 4M devices is measured and reported. We also imaged both polystyrene microspheres similar in size to epithelial cell nuclei and cervical cancer cells. Imaging results indicate that the 4M prototype can resolve cellular detail necessary for detection of precancer. PMID:19466016

  7. Image gathering and restoration - Information and visual quality

    NASA Technical Reports Server (NTRS)

    Mccormick, Judith A.; Alter-Gartenberg, Rachel; Huck, Friedrich O.

    1989-01-01

    A method is investigated for optimizing the end-to-end performance of image gathering and restoration for visual quality. To achieve this objective, one must inevitably confront the problems that the visual quality of restored images depends on perceptual rather than mathematical considerations and that these considerations vary with the target, the application, and the observer. The method adopted in this paper is to optimize image gathering informationally and to restore images interactively to obtain the visually preferred trade-off among fidelity resolution, sharpness, and clarity. The results demonstrate that this method leads to significant improvements in the visual quality obtained by the traditional digital processing methods. These traditional methods allow a significant loss of visual quality to occur because they treat the design of the image-gathering system and the formulation of the image-restoration algorithm as two separate tasks and fail to account for the transformations between the continuous and the discrete representations in image gathering and reconstruction.

  8. Gastroesophageal Reflux Affects Sleep Quality in Snoring Obese Children

    PubMed Central

    Woodley, Frederick W; Skaggs, Beth; Di Lorenzo, Carlo; Eneli, Ihuoma; Splaingard, Mark; Mousa, Hayat

    2016-01-01

    Purpose This study was performed to evaluate the quality of sleep in snoring obese children without obstructive sleep apnea (OSA); and to study the possible relationship between sleep interruption and gastroesophageal reflux (GER) in snoring obese children. Methods Study subjects included 13 snoring obese children who were referred to our sleep lab for possible sleep-disordered breathing. Patients underwent multichannel intraluminal impedance and esophageal pH monitoring with simultaneous polysomnography. Exclusion criteria included history of fundoplication, cystic fibrosis, and infants under the age of 2 years. Significant association between arousals and awakenings with previous reflux were defined by symptom-association probability using 2-minute intervals. Results Sleep efficiency ranged from 67-97% (median 81%). A total of 111 reflux episodes (90% acidic) were detected during sleep, but there were more episodes per hour during awake periods after sleep onset than during sleep (median 2.3 vs. 0.6, p=0.04). There were 279 total awakenings during the sleep study; 56 (20.1%) of them in 9 patients (69.2%) were preceded by reflux episodes (55 acid, 1 non-acid). In 5 patients (38.5%), awakenings were significantly associated with reflux. Conclusion The data suggest that acid GER causes sleep interruptions in obese children who have symptoms of snoring or restless sleep and without evidence of OSA. PMID:27066445

  9. Predicted image quality of a CMOS APS X-ray detector across a range of mammographic beam qualities

    NASA Astrophysics Data System (ADS)

    Konstantinidis, A.

    2015-09-01

    Digital X-ray detectors based on Complementary Metal-Oxide- Semiconductor (CMOS) Active Pixel Sensor (APS) technology have been introduced in the early 2000s in medical imaging applications. In a previous study the X-ray performance (i.e. presampling Modulation Transfer Function (pMTF), Normalized Noise Power Spectrum (NNPS), Signal-to-Noise Ratio (SNR) and Detective Quantum Efficiency (DQE)) of the Dexela 2923MAM CMOS APS X-ray detector was evaluated within the mammographic energy range using monochromatic synchrotron radiation (i.e. 17-35 keV). In this study image simulation was used to predict how the mammographic beam quality affects image quality. In particular, the experimentally measured monochromatic pMTF, NNPS and SNR parameters were combined with various mammographic spectral shapes (i.e. Molybdenum/Molybdenum (Mo/Mo), Rhodium/Rhodium (Rh/Rh), Tungsten/Aluminium (W/Al) and Tungsten/Rhodium (W/Rh) anode/filtration combinations at 28 kV). The image quality was measured in terms of Contrast-to-Noise Ratio (CNR) using a synthetic breast phantom (4 cm thick with 50% glandularity). The results can be used to optimize the imaging conditions in order to minimize patient's Mean Glandular Dose (MGD).

  10. The effect of image quality and forensic expertise in facial image comparisons.

    PubMed

    Norell, Kristin; Läthén, Klas Brorsson; Bergström, Peter; Rice, Allyson; Natu, Vaidehi; O'Toole, Alice

    2015-03-01

    Images of perpetrators in surveillance video footage are often used as evidence in court. In this study, identification accuracy was compared for forensic experts and untrained persons in facial image comparisons as well as the impact of image quality. Participants viewed thirty image pairs and were asked to rate the level of support garnered from their observations for concluding whether or not the two images showed the same person. Forensic experts reached their conclusions with significantly fewer errors than did untrained participants. They were also better than novices at determining when two high-quality images depicted the same person. Notably, lower image quality led to more careful conclusions by experts, but not for untrained participants. In summary, the untrained participants had more false negatives and false positives than experts, which in the latter case could lead to a higher risk of an innocent person being convicted for an untrained witness. PMID:25537273

  11. Peripheral Aberrations and Image Quality for Contact Lens Correction

    PubMed Central

    Shen, Jie; Thibos, Larry N.

    2011-01-01

    Purpose Contact lenses reduced the degree of hyperopic field curvature present in myopic eyes and rigid contact lenses reduced sphero-cylindrical image blur on the peripheral retina, but their effect on higher order aberrations and overall optical quality of the eye in the peripheral visual field is still unknown. The purpose of our study was to evaluate peripheral wavefront aberrations and image quality across the visual field before and after contact lens correction. Methods A commercial Hartmann-Shack aberrometer was used to measure ocular wavefront errors in 5° steps out to 30° of eccentricity along the horizontal meridian in uncorrected eyes and when the same eyes are corrected with soft or rigid contact lenses. Wavefront aberrations and image quality were determined for the full elliptical pupil encountered in off-axis measurements. Results Ocular higher-order aberrations increase away from fovea in the uncorrected eye. Third-order aberrations are larger and increase faster with eccentricity compared to the other higher-order aberrations. Contact lenses increase all higher-order aberrations except 3rd-order Zernike terms. Nevertheless, a net increase in image quality across the horizontal visual field for objects located at the foveal far point is achieved with rigid lenses, whereas soft contact lenses reduce image quality. Conclusions Second order aberrations limit image quality more than higher-order aberrations in the periphery. Although second-order aberrations are reduced by contact lenses, the resulting gain in image quality is partially offset by increased amounts of higher-order aberrations. To fully realize the benefits of correcting higher-order aberrations in the peripheral field requires improved correction of second-order aberrations as well. PMID:21873925

  12. Image science and image-quality research in the Optical Sciences Center

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.

    2014-09-01

    This paper reviews the history of research into imaging and image quality at the Optical Sciences Center (OSC), with emphasis on the period 1970-1990. The work of various students in the areas of psychophysical studies of human observers of images; mathematical model observers; image simulation and analysis, and the application of these methods to radiology and nuclear medicine is summarized. The rapid progress in computational power, at OSC and elsewhere, which enabled the steady advances in imaging and the emergence of a science of imaging, is also traced. The implications of these advances to ongoing research and the current Image Science curriculum at the College of Optical Sciences are discussed.

  13. APQ-102 imaging radar digital image quality study

    NASA Astrophysics Data System (ADS)

    Griffin, C. R.; Estes, J. M.

    1982-11-01

    A modified APQ-102 sidelooking radar collected synthetic aperture radar (SAR) data which was digitized and recorded on wideband magnetic tape. These tapes were then ground processed into computer compatible tapes (CCT's). The CCT's may then be processed into high resolution radar images by software on the CYBER computer.

  14. APQ-102 imaging radar digital image quality study

    NASA Technical Reports Server (NTRS)

    Griffin, C. R.; Estes, J. M.

    1982-01-01

    A modified APQ-102 sidelooking radar collected synthetic aperture radar (SAR) data which was digitized and recorded on wideband magnetic tape. These tapes were then ground processed into computer compatible tapes (CCT's). The CCT's may then be processed into high resolution radar images by software on the CYBER computer.

  15. Dietary fatty acids affect semen quality: a review.

    PubMed

    Esmaeili, V; Shahverdi, A H; Moghadasian, M H; Alizadeh, A R

    2015-05-01

    Mammalian spermatozoa are characterized by a high proportion of polyunsaturated fatty acids (PUFA) which play a crucial role in fertilization. This review focuses on analysis of sperm fatty acid profiles and the effects of omega-3, saturated and trans dietary and sperm fatty acids on sperm parameters. Two major points have been pivotal points of investigation in the field of sperm fatty acid profiles: first, the comparison between fatty acid profiles of fertile and infertile men and second, the effect of dietary fatty acids on sperm fatty acid profiles as well as sperm quality and quantity. Docosahexaenoic acid (DHA, C22:6n-3), and palmitic acid (C16:0) are the predominant PUFA and saturated fatty acids, respectively, in human sperm cells. Higher levels of DHA are concentrated on the sperm's head or tail varying among different species. However, the human sperm head contains a higher concentration of DHA. Dietary fatty acids influence on sperm fatty acid profiles and it seems that sperm fatty acid profiles are most sensitive to dietary omega-3 PUFA. Although improvements in sperm parameters are a response to omega-3 sources after more than 4 weeks of supplementation in the male diet, time-dependent and dose-dependent responses may explain the failure in some experiments. In human spermatozoa, elevated saturated or trans fatty acid concentration and a low DHA level is a concern. The regulations of the sperm fatty acid mean melting point as well as expression regulation of peroxisome proliferator-activated receptor gamma (PPARG) alongside with spermatozoon assembly, anti-apoptosis effects, eicosanoid formation, and hormone activity are the putative key factors that induce a response by inclusion of omega-3 PUFA. PMID:25951427

  16. Influence of acquisition parameters on MV-CBCT image quality.

    PubMed

    Gayou, Olivier

    2012-01-01

    The production of high quality pretreatment images plays an increasing role in image-guided radiotherapy (IGRT) and adaptive radiation therapy (ART). Megavoltage cone-beam computed tomography (MV-CBCT) is the simplest solution of all the commercially available volumetric imaging systems for localization. It also suffers the most from relatively poor contrast due to the energy range of the imaging photons. Several avenues can be investigated to improve MV-CBCT image quality while maintaining an acceptable patient exposure: beam generation, detector technology, reconstruction parameters, and acquisition parameters. This article presents a study of the effects of the acquisition scan length and number of projections of a Siemens Artiste MV-CBCT system on image quality within the range provided by the manufacturer. It also discusses other aspects not related to image quality one should consider when selecting an acquisition protocol. Noise and uniformity were measured on the image of a cylindrical water phantom. Spatial resolution was measured using the same phantom half filled with water to provide a sharp water/air interface to derive the modulation transfer function (MTF). Contrast-to-noise ratio (CNR) was measured on a pelvis-shaped phantom with four inserts of different electron densities relative to water (1.043, 1.117, 1.513, and 0.459). Uniformity was independent of acquisition protocol. Noise decreased from 1.96% to 1.64% when the total number of projections was increased from 100 to 600 for a total exposure of 13.5 MU. The CNR showed a ± 5% dependence on the number of projections and 10% dependence on the scan length. However, these variations were not statistically significant. The spatial resolution was unaffected by the arc length or the sampling rate. Acquisition parameters have little to no effect on the image quality of the MV-CBCT system within the range of parameters available on the system. Considerations other than image quality, such as memory

  17. Body image and quality of life in a Spanish population

    PubMed Central

    Lobera, Ignacio Jáuregui; Ríos, Patricia Bolaños

    2011-01-01

    Purpose The aim of the current study was to analyze the psychometric properties, factor structure, and internal consistency of the Spanish version of the Body Image Quality of Life Inventory (BIQLI-SP) as well as its test–retest reliability. Further objectives were to analyze different relationships with key dimensions of psychosocial functioning (ie, self-esteem, presence of psychopathological symptoms, eating and body image-related problems, and perceived stress) and to evaluate differences in body image quality of life due to gender. Patients and methods The sample comprised 417 students without any psychiatric history, recruited from the Pablo de Olavide University and the University of Seville. There were 140 men (33.57%) and 277 women (66.43%), and the mean age was 21.62 years (standard deviation = 5.12). After obtaining informed consent from all participants, the following questionnaires were administered: BIQLI, Eating Disorder Inventory-2 (EDI-2), Perceived Stress Questionnaire (PSQ), Self-Esteem Scale (SES), and Symptom Checklist-90-Revised (SCL-90-R). Results The BIQLI-SP shows adequate psychometric properties, and it may be useful to determine the body image quality of life in different physical conditions. A more positive body image quality of life is associated with better self-esteem, better psychological wellbeing, and fewer eating-related dysfunctional attitudes, this being more evident among women. Conclusion The BIQLI-SP may be useful to determine the body image quality of life in different contexts with regard to dermatology, cosmetic and reconstructive surgery, and endocrinology, among others. In these fields of study, a new trend has emerged to assess body image-related quality of life. PMID:21403794

  18. Evaluation of image quality in computed radiography based mammography systems

    NASA Astrophysics Data System (ADS)

    Singh, Abhinav; Bhwaria, Vipin; Valentino, Daniel J.

    2011-03-01

    Mammography is the most widely accepted procedure for the early detection of breast cancer and Computed Radiography (CR) is a cost-effective technology for digital mammography. We have demonstrated that CR mammography image quality is viable for Digital Mammography. The image quality of mammograms acquired using Computed Radiography technology was evaluated using the Modulation Transfer Function (MTF), Noise Power Spectrum (NPS) and Detective Quantum Efficiency (DQE). The measurements were made using a 28 kVp beam (RQA M-II) using 2 mm of Al as a filter and a target/filter combination of Mo/Mo. The acquired image bit depth was 16 bits and the pixel pitch for scanning was 50 microns. A Step-Wedge phantom (to measure the Contrast-to-noise ratio (CNR)) and the CDMAM 3.4 Contrast Detail phantom were also used to assess the image quality. The CNR values were observed at varying thickness of PMMA. The CDMAM 3.4 phantom results were plotted and compared to the EUREF acceptable and achievable values. The effect on image quality was measured using the physics metrics. A lower DQE was observed even with a higher MTF. This could be possibly due to a higher noise component present due to the way the scanner was configured. The CDMAM phantom scores demonstrated a contrast-detail comparable to the EUREF values. A cost-effective CR machine was optimized for high-resolution and high-contrast imaging.

  19. Analysis of image quality for laser display scanner test

    NASA Astrophysics Data System (ADS)

    Specht, H.; Kurth, S.; Billep, D.; Gessner, T.

    2009-02-01

    The scanning laser display technology is one of the most promising technologies for highly integrated projection display applications (e. g. in PDAs, mobile phones or head mounted displays) due to its advantages regarding image quality, miniaturization level and low cost potential. As a couple of research teams found during their investigations on laser scanning projections systems, the image quality of such systems is - beside from laser source and video signal processing - crucially determined by the scan engine, including MEMS scanner, driving electronics, scanning regime and synchronization. Even though a number of technical parameters can be measured with high accuracy, the test procedure is challenging because the influence of these parameters on image quality is often insufficiently understood. Thus, in many cases it is not clear how to define limiting values for characteristic parameters. In this paper the relationship between parameters characterizing the scan engine and their influence on image quality will be discussed. Those include scanner topography, geometry of the path of light as well as trajectory parameters. Understanding this enables a new methodology for testing and characterization of the scan engine, based on evaluation of one or a series of projected test images. Due to the fact that the evaluation process can be easily automated by digital image processing this methodology has the potential to become integrated into the production process of laser displays.

  20. HVAC SYSTEMS AS EMISSION SOURCES AFFECTING INDOOR AIR QUALITY: A CRITICAL REVIEW

    EPA Science Inventory

    The study evaluates heating, ventilating, and air-conditioning (HVAC) systems as contaminant emission sources that affect indoor air quality (IAQ). Various literature sources and methods for characterizing HVAC emission sources are reviewed. Available methods include in situ test...

  1. Image quality assessment with manifold and machine learning

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Lebrun, Gilles; Lezoray, Olivier

    2009-01-01

    A crucial step in image compression is the evaluation of its performance, and more precisely the available way to measure the final quality of the compressed image. In this paper, a machine learning expert, providing a final class number is designed. The quality measure is based on a learned classification process in order to respect the one of human observers. Instead of computing a final note, our method classifies the quality using the quality scale recommended by the UIT. This quality scale contains 5 ranks ordered from 1 (the worst quality) to 5 (the best quality). This was done constructing a vector containing many visual attributes. Finally, the final features vector contains more than 40 attibutes. Unfortunatley, no study about the existing interactions between the used visual attributes has been done. A feature selection algorithm could be interesting but the selection is highly related to the further used classifier. Therefore, we prefer to perform dimensionality reduction instead of feature selection. Manifold Learning methods are used to provide a low-dimensional new representation from the initial high dimensional feature space. The classification process is performed on this new low-dimensional representation of the images. Obtained results are compared to the one obtained without applying the dimension reduction process to judge the efficiency of the method.

  2. Faster, higher quality volume visualization for 3D medical imaging

    NASA Astrophysics Data System (ADS)

    Kalvin, Alan D.; Laine, Andrew F.; Song, Ting

    2008-03-01

    The two major volume visualization methods used in biomedical applications are Maximum Intensity Projection (MIP) and Volume Rendering (VR), both of which involve the process of creating sets of 2D projections from 3D images. We have developed a new method for very fast, high-quality volume visualization of 3D biomedical images, based on the fact that the inverse of this process (transforming 2D projections into a 3D image) is essentially equivalent to tomographic image reconstruction. This new method uses the 2D projections acquired by the scanner, thereby obviating the need for the two computationally expensive steps currently required in the complete process of biomedical visualization, that is, (i) reconstructing the 3D image from 2D projection data, and (ii) computing the set of 2D projections from the reconstructed 3D image As well as improvements in computation speed, this method also results in improvements in visualization quality, and in the case of x-ray CT we can exploit this quality improvement to reduce radiation dosage. In this paper, demonstrate the benefits of developing biomedical visualization techniques by directly processing the sensor data acquired by body scanners, rather than by processing the image data reconstructed from the sensor data. We show results of using this approach for volume visualization for tomographic modalities, like x-ray CT, and as well as for MRI.

  3. An approach for quantitative image quality analysis for CT

    NASA Astrophysics Data System (ADS)

    Rahimi, Amir; Cochran, Joe; Mooney, Doug; Regensburger, Joe

    2016-03-01

    An objective and standardized approach to assess image quality of Compute Tomography (CT) systems is required in a wide variety of imaging processes to identify CT systems appropriate for a given application. We present an overview of the framework we have developed to help standardize and to objectively assess CT image quality for different models of CT scanners used for security applications. Within this framework, we have developed methods to quantitatively measure metrics that should correlate with feature identification, detection accuracy and precision, and image registration capabilities of CT machines and to identify strengths and weaknesses in different CT imaging technologies in transportation security. To that end we have designed, developed and constructed phantoms that allow for systematic and repeatable measurements of roughly 88 image quality metrics, representing modulation transfer function, noise equivalent quanta, noise power spectra, slice sensitivity profiles, streak artifacts, CT number uniformity, CT number consistency, object length accuracy, CT number path length consistency, and object registration. Furthermore, we have developed a sophisticated MATLAB based image analysis tool kit to analyze CT generated images of phantoms and report these metrics in a format that is standardized across the considered models of CT scanners, allowing for comparative image quality analysis within a CT model or between different CT models. In addition, we have developed a modified sparse principal component analysis (SPCA) method to generate a modified set of PCA components as compared to the standard principal component analysis (PCA) with sparse loadings in conjunction with Hotelling T2 statistical analysis method to compare, qualify, and detect faults in the tested systems.

  4. Evaluating the real-world predictive validity of the Body Image Quality of Life Inventory using Ecological Momentary Assessment.

    PubMed

    Heron, Kristin E; Mason, Tyler B; Sutton, Tiphanie G; Myers, Taryn A

    2015-09-01

    Perceptions of physical appearance, or body image, can affect psychosocial functioning and quality of life (QOL). The present study evaluated the real-world predictive validity of the Body Image Quality of Life Inventory (BIQLI) using Ecological Momentary Assessment (EMA). College women reporting subclinical disordered eating/body dissatisfaction (N=131) completed the BIQLI and related measures. For one week they then completed five daily EMA surveys of mood, social interactions, stress, and eating behaviors on palmtop computers. Results showed better body image QOL was associated with less negative affect, less overwhelming emotions, more positive affect, more pleasant social interactions, and higher self-efficacy for handling stress. Lower body image QOL was marginally related to less overeating and lower loss of control over eating in daily life. To our knowledge, this is the first study to support the real-world predictive validity of the BIQLI by identifying social, affective, and behavioral correlates in everyday life using EMA. PMID:26302376

  5. Proteomic studies on soybean seed quality as affected by high temperature

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Long-term high temperature stresses can occur during soybean seed development through maturity and negatively impact seed quality. We investigated soybean seed quality as affected by high temperature using a proteomic approach. The effects of a prolonged high temperature treatment (37/30ºC day/nigh...

  6. Quality assurance of ultrasound imaging instruments by monitoring the monitor.

    PubMed

    Walker, J B; Thorne, G C; Halliwell, M

    1993-11-01

    Ultrasound quality assurance (QA) is a means of assuring the constant performance of an ultrasound instrument. A novel 'ultrasound image analyser' has been developed to allow objective, accurate and repeatable measurement of the image displayed on the ultrasound screen, i.e. as seen by the operator. The analyser uses a television camera/framestore combination to digitize and analyse this image. A QA scheme is described along with the procedures necessary to obtain a repeatable measurement of the image so that comparisons with earlier good images can be made. These include repositioning the camera and resetting the video display characteristics. The advantages of using the analyser over other methods are discussed. It is concluded that the analyser has distinct advantages over subjective image assessment methods and will be a valuable addition to current ultrasound QA programmes. PMID:8272435

  7. The influence of noise on image quality in phase-diverse coherent diffraction imaging

    NASA Astrophysics Data System (ADS)

    Wittler, H. P. A.; van Riessen, G. A.; Jones, M. W. M.

    2016-02-01

    Phase-diverse coherent diffraction imaging provides a route to high sensitivity and resolution with low radiation dose. To take full advantage of this, the characteristics and tolerable limits of measurement noise for high quality images must be understood. In this work we show the artefacts that manifest in images recovered from simulated data with noise of various characteristics in the illumination and diffraction pattern. We explore the limits at which images of acceptable quality can be obtained and suggest qualitative guidelines that would allow for faster data acquisition and minimize radiation dose.

  8. Real-time computer treatment of THz passive device images with the high image quality

    NASA Astrophysics Data System (ADS)

    Trofimov, Vyacheslav A.; Trofimov, Vladislav V.

    2012-06-01

    We demonstrate real-time computer code improving significantly the quality of images captured by the passive THz imaging system. The code is not only designed for a THz passive device: it can be applied to any kind of such devices and active THz imaging systems as well. We applied our code for computer processing of images captured by four passive THz imaging devices manufactured by different companies. It should be stressed that computer processing of images produced by different companies requires using the different spatial filters usually. The performance of current version of the computer code is greater than one image per second for a THz image having more than 5000 pixels and 24 bit number representation. Processing of THz single image produces about 20 images simultaneously corresponding to various spatial filters. The computer code allows increasing the number of pixels for processed images without noticeable reduction of image quality. The performance of the computer code can be increased many times using parallel algorithms for processing the image. We develop original spatial filters which allow one to see objects with sizes less than 2 cm. The imagery is produced by passive THz imaging devices which captured the images of objects hidden under opaque clothes. For images with high noise we develop an approach which results in suppression of the noise after using the computer processing and we obtain the good quality image. With the aim of illustrating the efficiency of the developed approach we demonstrate the detection of the liquid explosive, ordinary explosive, knife, pistol, metal plate, CD, ceramics, chocolate and other objects hidden under opaque clothes. The results demonstrate the high efficiency of our approach for the detection of hidden objects and they are a very promising solution for the security problem.

  9. Exploratory survey of image quality on CR digital mammography imaging systems in Mexico.

    PubMed

    Gaona, E; Rivera, T; Arreola, M; Franco, J; Molina, N; Alvarez, B; Azorín, C G; Casian, G

    2014-01-01

    The purpose of this study was to assess the current status of image quality and dose in computed radiographic digital mammography (CRDM) systems. Studies included CRDM systems of various models and manufacturers which dose and image quality comparisons were performed. Due to the recent rise in the use of digital radiographic systems in Mexico, CRDM systems are rapidly replacing conventional film-screen systems without any regard to quality control or image quality standards. Study was conducted in 65 mammography facilities which use CRDM systems in the Mexico City and surrounding States. The systems were tested as used clinically. This means that the dose and beam qualities were selected using the automatic beam selection and photo-timed features. All systems surveyed generate laser film hardcopies for the radiologist to read on a scope or mammographic high luminance light box. It was found that 51 of CRDM systems presented a variety of image artefacts and non-uniformities arising from inadequate acquisition and processing, as well as from the laser printer itself. Undisciplined alteration of image processing settings by the technologist was found to be a serious prevalent problem in 42 facilities. Only four of them showed an image QC program which is periodically monitored by a medical physicist. The Average Glandular Dose (AGD) in the surveyed systems was estimated to have a mean value of 2.4 mGy. To improve image quality in mammography and make more efficient screening mammographic in early detection of breast cancer is required new legislation. PMID:23938078

  10. Soil moisture affects fatty acids and oil quality parameters in peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Drought affects yield of peanut, but its effect on oleic and linoleic acids that influence its oil quality of peanut genotypes with different levels of drought resistance has not been clearly investigated. Therefore, the aims of this research were to determine whether soil water levels could affect...

  11. Determination of pasture quality using airborne hyperspectral imaging

    NASA Astrophysics Data System (ADS)

    Pullanagari, R. R.; Kereszturi, G.; Yule, Ian J.; Irwin, M. E.

    2015-10-01

    Pasture quality is a critical determinant which influences animal performance (live weight gain, milk and meat production) and animal health. Assessment of pasture quality is therefore required to assist farmers with grazing planning and management, benchmarking between seasons and years. Traditionally, pasture quality is determined by field sampling which is laborious, expensive and time consuming, and the information is not available in real-time. Hyperspectral remote sensing has potential to accurately quantify biochemical composition of pasture over wide areas in great spatial detail. In this study an airborne imaging spectrometer (AisaFENIX, Specim) was used with a spectral range of 380-2500 nm with 448 spectral bands. A case study of a 600 ha hill country farm in New Zealand is used to illustrate the use of the system. Radiometric and atmospheric corrections, along with automatized georectification of the imagery using Digital Elevation Model (DEM), were applied to the raw images to convert into geocoded reflectance images. Then a multivariate statistical method, partial least squares (PLS), was applied to estimate pasture quality such as crude protein (CP) and metabolisable energy (ME) from canopy reflectance. The results from this study revealed that estimates of CP and ME had a R2 of 0.77 and 0.79, and RMSECV of 2.97 and 0.81 respectively. By utilizing these regression models, spatial maps were created over the imaged area. These pasture quality maps can be used for adopting precision agriculture practices which improves farm profitability and environmental sustainability.

  12. No-reference image quality assessment for horizontal-path imaging scenarios

    NASA Astrophysics Data System (ADS)

    Rios, Carlos; Gladysz, Szymon

    2013-05-01

    There exist several image-enhancement algorithms and tasks associated with imaging through turbulence that depend on defining the quality of an image. Examples include: "lucky imaging", choosing the width of the inverse filter for image reconstruction, or stopping iterative deconvolution. We collected a number of image quality metrics found in the literature. Particularly interesting are the blind, "no-reference" metrics. We discuss ways of evaluating the usefulness of these metrics, even when a fully objective comparison is impossible because of the lack of a reference image. Metrics are tested on simulated and real data. Field data comes from experiments performed by the NATO SET 165 research group over a 7 km distance in Dayton, Ohio.

  13. Perceived assessment metrics for visible and infrared color fused image quality without reference image

    NASA Astrophysics Data System (ADS)

    Yu, Xuelian; Chen, Qian; Gu, Guohua; Ren, Jianle; Sui, Xiubao

    2015-02-01

    Designing objective quality assessment of color-fused image is a very demanding and challenging task. We propose four no-reference metrics based on human visual system characteristics for objectively evaluating the quality of false color fusion image. The perceived edge metric (PEM) is defined based on visual perception model and color image gradient similarity between the fused image and the source images. The perceptual contrast metric (PCM) is established associating multi-scale contrast and varying contrast sensitivity filter (CSF) with color components. The linear combination of the standard deviation and mean value over the fused image construct the image colorfulness metric (ICM). The color comfort metric (CCM) is designed by the average saturation and the ratio of pixels with high and low saturation. The qualitative and quantitative experimental results demonstrate that the proposed metrics have a good agreement with subjective perception.

  14. Radiation dose and image quality for paediatric interventional cardiology

    NASA Astrophysics Data System (ADS)

    Vano, E.; Ubeda, C.; Leyton, F.; Miranda, P.

    2008-08-01

    Radiation dose and image quality for paediatric protocols in a biplane x-ray system used for interventional cardiology have been evaluated. Entrance surface air kerma (ESAK) and image quality using a test object and polymethyl methacrylate (PMMA) phantoms have been measured for the typical paediatric patient thicknesses (4-20 cm of PMMA). Images from fluoroscopy (low, medium and high) and cine modes have been archived in digital imaging and communications in medicine (DICOM) format. Signal-to-noise ratio (SNR), figure of merit (FOM), contrast (CO), contrast-to-noise ratio (CNR) and high contrast spatial resolution (HCSR) have been computed from the images. Data on dose transferred to the DICOM header have been used to test the values of the dosimetric display at the interventional reference point. ESAK for fluoroscopy modes ranges from 0.15 to 36.60 µGy/frame when moving from 4 to 20 cm PMMA. For cine, these values range from 2.80 to 161.10 µGy/frame. SNR, FOM, CO, CNR and HCSR are improved for high fluoroscopy and cine modes and maintained roughly constant for the different thicknesses. Cumulative dose at the interventional reference point resulted 25-45% higher than the skin dose for the vertical C-arm (depending of the phantom thickness). ESAK and numerical image quality parameters allow the verification of the proper setting of the x-ray system. Knowing the increases in dose per frame when increasing phantom thicknesses together with the image quality parameters will help cardiologists in the good management of patient dose and allow them to select the best imaging acquisition mode during clinical procedures.

  15. Radiometric quality evaluation of ZY-02C satellite panchromatic image

    NASA Astrophysics Data System (ADS)

    Zhao, Fengfan; Sun, Ke; Yang, Lei

    2014-11-01

    As the second Chinese civilian high spatial resolution satellite, the ZY-02C satellite was successfully launched on December 22, 2011. In this paper, we used two different methods, subjective evaluation and external evaluation, to evaluate radiation quality of ZY-02C panchromatic image, meanwhile, we compared with quality of CBERS-02B, SPOT-5 satellite. The external evaluation could give us quantitative image quality. The EIFOV of ZY-02C, one of parameters, is less than SPOT-5. The results demonstrate the spatial resolution of ZY-02C is greater than SPOT-5. The subjective results show that the quality of SPOT-5 is little preferable to ZY-02C - CBERS-02B, and the quality of ZY-02C is better than CBERS-02B for most land-cover types. The results in the subjective evaluation and the external evaluation show the excellent agreement. Therefore the comprehensive result of the image quality will be got based on combining parameters introduced in this paper.

  16. Exploiting the multiplicative nature of fluoroscopic image stochastic noise to enhance calcium imaging recording quality.

    PubMed

    Esposti, Federico; Ripamonti, Maddalena; Signorini, Maria G

    2009-01-01

    One of the main problems that affect fluoroscopic imaging is the difficulty in coupling the recorded activity with the morphological information. The comprehension of fluorescence events in relationship with the internal structure of the cell can be very difficult. At this purpose, we developed a new method able to maximize the fluoroscopic movie quality. The method (Maximum Intensity Enhancement, MIE) works as follow: considering all the frames that compose the fluoroscopic movie, the algorithm extracts, for each pixel of the matrix, the maximal brightness value assumed along all the frames. Such values are collected in a maximum intensity matrix. Then, the method provides the projection of the target molecule oscillations which are present in the DeltaF/F(0) movie onto the maximum intensity matrix. This is done by creating a RGB movie and by assigning to the normalized (DeltaF/F(0)) activity a single channel and by reproducing the maximum intensity matrix on all the frames by using the remaining color channels. The application of such a method to fluoroscopic calcium imaging of astrocyte cultures demonstrated a meaningful enhancement in the possibility to discern the internal and external structure of cells. PMID:19964305

  17. Dose and diagnostic image quality in digital tomosynthesis imaging of facial bones in pediatrics

    NASA Astrophysics Data System (ADS)

    King, J. M.; Hickling, S.; Elbakri, I. A.; Reed, M.; Wrogemann, J.

    2011-03-01

    The purpose of this study was to evaluate the use of digital tomosynthesis (DT) for pediatric facial bone imaging. We compared the eye lens dose and diagnostic image quality of DT facial bone exams relative to digital radiography (DR) and computed tomography (CT), and investigated whether we could modify our current DT imaging protocol to reduce patient dose while maintaining sufficient diagnostic image quality. We measured the dose to the eye lens for all three modalities using high-sensitivity thermoluminescent dosimeters (TLDs) and an anthropomorphic skull phantom. To assess the diagnostic image quality of DT compared to the corresponding DR and CT images, we performed an observer study where the visibility of anatomical structures in the DT phantom images were rated on a four-point scale. We then acquired DT images at lower doses and had radiologists indicate whether the visibility of each structure was adequate for diagnostic purposes. For typical facial bone exams, we measured eye lens doses of 0.1-0.4 mGy for DR, 0.3-3.7 mGy for DT, and 26 mGy for CT. In general, facial bone structures were visualized better with DT then DR, and the majority of structures were visualized well enough to avoid the need for CT. DT imaging provides high quality diagnostic images of the facial bones while delivering significantly lower doses to the lens of the eye compared to CT. In addition, we found that by adjusting the imaging parameters, the DT effective dose can be reduced by up to 50% while maintaining sufficient image quality.

  18. Perceived Image Quality Improvements from the Application of Image Deconvolution to Retinal Images from an Adaptive Optics Fundus Imager

    NASA Astrophysics Data System (ADS)

    Soliz, P.; Nemeth, S. C.; Erry, G. R. G.; Otten, L. J.; Yang, S. Y.

    Aim: The objective of this project was to apply an image restoration methodology based on wavefront measurements obtained with a Shack-Hartmann sensor and evaluating the restored image quality based on medical criteria.Methods: Implementing an adaptive optics (AO) technique, a fundus imager was used to achieve low-order correction to images of the retina. The high-order correction was provided by deconvolution. A Shack-Hartmann wavefront sensor measures aberrations. The wavefront measurement is the basis for activating a deformable mirror. Image restoration to remove remaining aberrations is achieved by direct deconvolution using the point spread function (PSF) or a blind deconvolution. The PSF is estimated using measured wavefront aberrations. Direct application of classical deconvolution methods such as inverse filtering, Wiener filtering or iterative blind deconvolution (IBD) to the AO retinal images obtained from the adaptive optical imaging system is not satisfactory because of the very large image size, dificulty in modeling the system noise, and inaccuracy in PSF estimation. Our approach combines direct and blind deconvolution to exploit available system information, avoid non-convergence, and time-consuming iterative processes. Results: The deconvolution was applied to human subject data and resulting restored images compared by a trained ophthalmic researcher. Qualitative analysis showed significant improvements. Neovascularization can be visualized with the adaptive optics device that cannot be resolved with the standard fundus camera. The individual nerve fiber bundles are easily resolved as are melanin structures in the choroid. Conclusion: This project demonstrated that computer-enhanced, adaptive optic images have greater detail of anatomical and pathological structures.

  19. Flattening filter removal for improved image quality of megavoltage fluoroscopy

    SciTech Connect

    Christensen, James D.; Kirichenko, Alexander; Gayou, Olivier

    2013-08-15

    Purpose: Removal of the linear accelerator (linac) flattening filter enables a high rate of dose deposition with reduced treatment time. When used for megavoltage imaging, an unflat beam has reduced primary beam scatter resulting in sharper images. In fluoroscopic imaging mode, the unflat beam has higher photon count per image frame yielding higher contrast-to-noise ratio. The authors’ goal was to quantify the effects of an unflat beam on the image quality of megavoltage portal and fluoroscopic images.Methods: 6 MV projection images were acquired in fluoroscopic and portal modes using an electronic flat-panel imager. The effects of the flattening filter on the relative modulation transfer function (MTF) and contrast-to-noise ratio were quantified using the QC3 phantom. The impact of FF removal on the contrast-to-noise ratio of gold fiducial markers also was studied under various scatter conditions.Results: The unflat beam had improved contrast resolution, up to 40% increase in MTF contrast at the highest frequency measured (0.75 line pairs/mm). The contrast-to-noise ratio was increased as expected from the increased photon flux. The visualization of fiducial markers was markedly better using the unflat beam under all scatter conditions, enabling visualization of thin gold fiducial markers, the thinnest of which was not visible using the unflat beam.Conclusions: The removal of the flattening filter from a clinical linac leads to quantifiable improvements in the image quality of megavoltage projection images. These gains enable observers to more easily visualize thin fiducial markers and track their motion on fluoroscopic images.

  20. Image quality testing of assembled IR camera modules

    NASA Astrophysics Data System (ADS)

    Winters, Daniel; Erichsen, Patrik

    2013-10-01

    Infrared (IR) camera modules for the LWIR (8-12_m) that combine IR imaging optics with microbolometer focal plane array (FPA) sensors with readout electronics are becoming more and more a mass market product. At the same time, steady improvements in sensor resolution in the higher priced markets raise the requirement for imaging performance of objectives and the proper alignment between objective and FPA. This puts pressure on camera manufacturers and system integrators to assess the image quality of finished camera modules in a cost-efficient and automated way for quality control or during end-of-line testing. In this paper we present recent development work done in the field of image quality testing of IR camera modules. This technology provides a wealth of additional information in contrast to the more traditional test methods like minimum resolvable temperature difference (MRTD) which give only a subjective overall test result. Parameters that can be measured are image quality via the modulation transfer function (MTF) for broadband or with various bandpass filters on- and off-axis and optical parameters like e.g. effective focal length (EFL) and distortion. If the camera module allows for refocusing the optics, additional parameters like best focus plane, image plane tilt, auto-focus quality, chief ray angle etc. can be characterized. Additionally, the homogeneity and response of the sensor with the optics can be characterized in order to calculate the appropriate tables for non-uniformity correction (NUC). The technology can also be used to control active alignment methods during mechanical assembly of optics to high resolution sensors. Other important points that are discussed are the flexibility of the technology to test IR modules with different form factors, electrical interfaces and last but not least the suitability for fully automated measurements in mass production.

  1. Impact of atmospheric aerosols on long range image quality

    NASA Astrophysics Data System (ADS)

    LeMaster, Daniel A.; Eismann, Michael T.

    2012-06-01

    Image quality in high altitude long range imaging systems can be severely limited by atmospheric absorption, scattering, and turbulence. Atmospheric aerosols contribute to this problem by scattering target signal out of the optical path and by scattering in unwanted light from the surroundings. Target signal scattering may also lead to image blurring though, in conventional modeling, this effect is ignored. The validity of this choice is tested in this paper by developing an aerosol modulation transfer function (MTF) model for an inhomogeneous atmosphere and then applying it to real-world scenarios using MODTRAN derived scattering parameters. The resulting calculations show that aerosol blurring can be effectively ignored.

  2. Pyramid wavefront sensor for image quality evaluation of optical system

    NASA Astrophysics Data System (ADS)

    Chen, Zhendong

    2015-08-01

    When the pyramid wavefront sensor is used to evaluate the imaging quality, placed at the focal plane of the aberrated optical system e.g., a telescope, it splits the light into four beams. Four images of the pupil are created on the detector and the detection signals of the pyramid wavefront sensor are calculated with these four intensity patterns, providing information on the derivatives of the aberrated wavefront. Based on the theory of the pyramid wavefront sensor, we are going to develop simulation software and a wavefront detector which can be used to test the imaging quality of the telescope. In our system, the subpupil image intensity through the pyramid sensor is calculated to obtain the aberration of wavefront where the piston, tilt, defocus, spherical, coma, astigmatism and other high level aberrations are separately represented by Zernike polynomials. The imaging quality of the optical system is then evaluated by the subsequent wavefront reconstruction. The performance of our system is to be checked by comparing with the measurements carried out using Puntino wavefront instrument (the method of SH wavefront sensor). Within this framework, the measurement precision of pyramid sensor will be discussed as well through detailed experiments. In general, this project would be very helpful both in our understanding of the principle of the wavefront reconstruction and its future technical applications. So far, we have produced the pyramid and established the laboratory setup of the image quality detecting system based on this wavefront sensor. Preliminary results are obtained, in that we have obtained the intensity images of the four pupils. Additional work is needed to analyze the characteristics of the pyramid wavefront sensor.

  3. Image quality-based adaptive illumination normalisation for face recognition

    NASA Astrophysics Data System (ADS)

    Sellahewa, Harin; Jassim, Sabah A.

    2009-05-01

    Automatic face recognition is a challenging task due to intra-class variations. Changes in lighting conditions during enrolment and identification stages contribute significantly to these intra-class variations. A common approach to address the effects such of varying conditions is to pre-process the biometric samples in order normalise intra-class variations. Histogram equalisation is a widely used illumination normalisation technique in face recognition. However, a recent study has shown that applying histogram equalisation on well-lit face images could lead to a decrease in recognition accuracy. This paper presents a dynamic approach to illumination normalisation, based on face image quality. The quality of a given face image is measured in terms of its luminance distortion by comparing this image against a known reference face image. Histogram equalisation is applied to a probe image if its luminance distortion is higher than a predefined threshold. We tested the proposed adaptive illumination normalisation method on the widely used Extended Yale Face Database B. Identification results demonstrate that our adaptive normalisation produces better identification accuracy compared to the conventional approach where every image is normalised, irrespective of the lighting condition they were acquired.

  4. VSI: a visual saliency-induced index for perceptual image quality assessment.

    PubMed

    Zhang, Lin; Shen, Ying; Li, Hongyu

    2014-10-01

    Perceptual image quality assessment (IQA) aims to use computational models to measure the image quality in consistent with subjective evaluations. Visual saliency (VS) has been widely studied by psychologists, neurobiologists, and computer scientists during the last decade to investigate, which areas of an image will attract the most attention of the human visual system. Intuitively, VS is closely related to IQA in that suprathreshold distortions can largely affect VS maps of images. With this consideration, we propose a simple but very effective full reference IQA method using VS. In our proposed IQA model, the role of VS is twofold. First, VS is used as a feature when computing the local quality map of the distorted image. Second, when pooling the quality score, VS is employed as a weighting function to reflect the importance of a local region. The proposed IQA index is called visual saliency-based index (VSI). Several prominent computational VS models have been investigated in the context of IQA and the best one is chosen for VSI. Extensive experiments performed on four large-scale benchmark databases demonstrate that the proposed IQA index VSI works better in terms of the prediction accuracy than all state-of-the-art IQA indices we can find while maintaining a moderate computational complexity. The MATLAB source code of VSI and the evaluation results are publicly available online at http://sse.tongji.edu.cn/linzhang/IQA/VSI/VSI.htm. PMID:25122572

  5. Criterion to Evaluate the Quality of Infrared Small Target Images

    NASA Astrophysics Data System (ADS)

    Mao, Xia; Diao, Wei-He

    2009-01-01

    In this paper, we propose a new criterion to estimate the quality of infrared small target images. To describe the criterion quantitatively, two indicators are defined. One is the “degree of target being confused” that represents the ability of infrared small target image to provide fake targets. The other one is the “degree of target being shielded”, which reflects the contribution of the image to shield the target. Experimental results reveal that this criterion is more robust than the traditional method (Signal-to-Noise Ratio). It is not only valid to infrared small target images which Signal-to-Noise Ratio could correctly describe, but also to the images that the traditional criterion could not accurately estimate. In addition, the results of this criterion can provide information about the cause of background interfering with target detection.

  6. DIANE stationary neutron radiography system image quality and industrial applications

    NASA Astrophysics Data System (ADS)

    Cluzeau, S.; Huet, J.; Le Tourneur, P.

    1994-05-01

    The SODERN neutron radiography laboratory has operated since February 1993 using a sealed tube generator (GENIE 46). An experimental programme of characterization (dosimetry, spectroscopy) has confirmed the expected performances concerning: neutron flux intensity, neutron energy range, residual gamma flux. Results are given in a specific report [2]. This paper is devoted to the image performance reporting. ASTM and specific indicators have been used to test the image quality with various converters and films. The corresponding modulation transfer functions are to be determined from image processing. Some industrial applications have demonstrated the capabilities of the system: corrosion detection in aircraft parts, ammunitions filling testing, detection of polymer lacks in sandwich steel sheets, detection of moisture in a probe for geophysics, residual ceramic cores imaging in turbine blades. Various computerized electronic imaging systems will be tested to improve the industrial capabilities.

  7. Image quality, space-qualified UV interference filters

    NASA Technical Reports Server (NTRS)

    Mooney, Thomas A.

    1992-01-01

    The progress during the contract period is described. The project involved fabrication of image quality, space-qualified bandpass filters in the 200-350 nm spectral region. Ion-assisted deposition (IAD) was applied to produce stable, reasonably durable filter coatings on space compatible UV substrates. Thin film materials and UV transmitting substrates were tested for resistance to simulated space effects.

  8. Perceived interest versus overt visual attention in image quality assessment

    NASA Astrophysics Data System (ADS)

    Engelke, Ulrich; Zhang, Wei; Le Callet, Patrick; Liu, Hantao

    2015-03-01

    We investigate the impact of overt visual attention and perceived interest on the prediction performance of image quality metrics. Towards this end we performed two respective experiments to capture these mechanisms: an eye gaze tracking experiment and a region-of-interest selection experiment. Perceptual relevance maps were created from both experiments and integrated into the design of the image quality metrics. Correlation analysis shows that indeed there is an added value of integrating these perceptual relevance maps. We reveal that the improvement in prediction accuracy is not statistically different between fixation density maps from eye gaze tracking data and region-of-interest maps, thus, indicating the robustness of different perceptual relevance maps for the performance gain of image quality metrics. Interestingly, however, we found that thresholding of region-of-interest maps into binary maps significantly deteriorates prediction performance gain for image quality metrics. We provide a detailed analysis and discussion of the results as well as the conceptual and methodological differences between capturing overt visual attention and perceived interest.

  9. SCID: full reference spatial color image quality metric

    NASA Astrophysics Data System (ADS)

    Ouni, S.; Chambah, M.; Herbin, M.; Zagrouba, E.

    2009-01-01

    The most used full reference image quality assessments are error-based methods. Thus, these measures are performed by pixel based difference metrics like Delta E ( E), MSE, PSNR, etc. Therefore, a local fidelity of the color is defined. However, these metrics does not correlate well with the perceived image quality. Indeed, they omit the properties of the HVS. Thus, they cannot be a reliable predictor of the perceived visual quality. All this metrics compute the differences pixel to pixel. Therefore, a local fidelity of the color is defined. However, the human visual system is rather sensitive to a global quality. In this paper, we present a novel full reference color metric that is based on characteristics of the human visual system by considering the notion of adjacency. This metric called SCID for Spatial Color Image Difference, is more perceptually correlated than other color differences such as Delta E. The suggested full reference metric is generic and independent of image distortion type. It can be used in different application such as: compression, restoration, etc.

  10. Simultaneous Analysis and Quality Assurance for Diffusion Tensor Imaging

    PubMed Central

    Lauzon, Carolyn B.; Asman, Andrew J.; Esparza, Michael L.; Burns, Scott S.; Fan, Qiuyun; Gao, Yurui; Anderson, Adam W.; Davis, Nicole; Cutting, Laurie E.; Landman, Bennett A.

    2013-01-01

    Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low

  11. Simultaneous analysis and quality assurance for diffusion tensor imaging.

    PubMed

    Lauzon, Carolyn B; Asman, Andrew J; Esparza, Michael L; Burns, Scott S; Fan, Qiuyun; Gao, Yurui; Anderson, Adam W; Davis, Nicole; Cutting, Laurie E; Landman, Bennett A

    2013-01-01

    Diffusion tensor imaging (DTI) enables non-invasive, cyto-architectural mapping of in vivo tissue microarchitecture through voxel-wise mathematical modeling of multiple magnetic resonance imaging (MRI) acquisitions, each differently sensitized to water diffusion. DTI computations are fundamentally estimation processes and are sensitive to noise and artifacts. Despite widespread adoption in the neuroimaging community, maintaining consistent DTI data quality remains challenging given the propensity for patient motion, artifacts associated with fast imaging techniques, and the possibility of hardware changes/failures. Furthermore, the quantity of data acquired per voxel, the non-linear estimation process, and numerous potential use cases complicate traditional visual data inspection approaches. Currently, quality inspection of DTI data has relied on visual inspection and individual processing in DTI analysis software programs (e.g. DTIPrep, DTI-studio). However, recent advances in applied statistical methods have yielded several different metrics to assess noise level, artifact propensity, quality of tensor fit, variance of estimated measures, and bias in estimated measures. To date, these metrics have been largely studied in isolation. Herein, we select complementary metrics for integration into an automatic DTI analysis and quality assurance pipeline. The pipeline completes in 24 hours, stores statistical outputs, and produces a graphical summary quality analysis (QA) report. We assess the utility of this streamlined approach for empirical quality assessment on 608 DTI datasets from pediatric neuroimaging studies. The efficiency and accuracy of quality analysis using the proposed pipeline is compared with quality analysis based on visual inspection. The unified pipeline is found to save a statistically significant amount of time (over 70%) while improving the consistency of QA between a DTI expert and a pool of research associates. Projection of QA metrics to a low

  12. A Novel Image Quality Assessment With Globally and Locally Consilient Visual Quality Perception.

    PubMed

    Bae, Sung-Ho; Kim, Munchurl

    2016-05-01

    Computational models for image quality assessment (IQA) have been developed by exploring effective features that are consistent with the characteristics of a human visual system (HVS) for visual quality perception. In this paper, we first reveal that many existing features used in computational IQA methods can hardly characterize visual quality perception for local image characteristics and various distortion types. To solve this problem, we propose a new IQA method, called the structural contrast-quality index (SC-QI), by adopting a structural contrast index (SCI), which can well characterize local and global visual quality perceptions for various image characteristics with structural-distortion types. In addition to SCI, we devise some other perceptually important features for our SC-QI that can effectively reflect the characteristics of HVS for contrast sensitivity and chrominance component variation. Furthermore, we develop a modified SC-QI, called structural contrast distortion metric (SC-DM), which inherits desirable mathematical properties of valid distance metricability and quasi-convexity. So, it can effectively be used as a distance metric for image quality optimization problems. Extensive experimental results show that both SC-QI and SC-DM can very well characterize the HVS's properties of visual quality perception for local image characteristics and various distortion types, which is a distinctive merit of our methods compared with other IQA methods. As a result, both SC-QI and SC-DM have better performances with a strong consilience of global and local visual quality perception as well as with much lower computation complexity, compared with the state-of-the-art IQA methods. The MATLAB source codes of the proposed SC-QI and SC-DM are publicly available online at https://sites.google.com/site/sunghobaecv/iqa. PMID:27046873

  13. Optoelectronic complex inner product for evaluating quality of image segmentation

    NASA Astrophysics Data System (ADS)

    Power, Gregory J.; Awwal, Abdul Ahad S.

    2000-11-01

    In automatic target recognition and machine vision applications, segmentation of the images is a key step. Poor segmentation reduces the recognition performance. For some imaging systems such as MRI and Synthetic Aperture Radar (SAR) it is difficult even for humans to agree on the location of the edge which allows for segmentation. A real- time dynamic approach to determine the quality of segmentation can enable vision systems to refocus of apply appropriate algorithms to ensure high quality segmentation for recognition. A recent approach to evaluate the quality of image segmentation uses percent-pixels-different (PPD). For some cases, PPD provides a reasonable quality evaluation, but it has a weakness in providing a measure for how well the shape of the segmentation matches the true shape. This paper introduces the complex inner product approach for providing a goodness measure for evaluating the segmentation quality based on shape. The complex inner product approach is demonstrated on SAR target chips obtained from the Moving and Stationary Target Acquisition and Recognition (MSTAR) program sponsored by the Defense Advanced Research Projects Agency (DARPA) and the Air Force Research Laboratory (AFRL). The results are compared to the PPD approach. A design for an optoelectronic implementation of the complex inner product for dynamic segmentation evaluation is introduced.

  14. Television Images: Exploring How They Affect People's View of Self and Others

    ERIC Educational Resources Information Center

    Alexandrin, Julie R.

    2009-01-01

    Through television, many different images of ethnic, cultural, and ability groups are presented. Different people perceive these images in different ways. These perceptions affect how people value themselves and judge and interact with others. This article first summaries research on TV images and people's meaning and reaction to them. Second, it…

  15. Factors Affecting Parent's Perception on Air Quality-From the Individual to the Community Level.

    PubMed

    Guo, Yulin; Liu, Fengfeng; Lu, Yuanan; Mao, Zongfu; Lu, Hanson; Wu, Yanyan; Chu, Yuanyuan; Yu, Lichen; Liu, Yisi; Ren, Meng; Li, Na; Chen, Xi; Xiang, Hao

    2016-01-01

    The perception of air quality significantly affects the acceptance of the public of the government's environmental policies. The aim of this research is to explore the relationship between the perception of the air quality of parents and scientific monitoring data and to analyze the factors that affect parents' perceptions. Scientific data of air quality were obtained from Wuhan's environmental condition reports. One thousand parents were investigated for their knowledge and perception of air quality. Scientific data show that the air quality of Wuhan follows an improving trend in general, while most participants believed that the air quality of Wuhan has deteriorated, which indicates a significant difference between public perception and reality. On the individual level, respondents with an age of 40 or above (40 or above: OR = 3.252; 95% CI: 1.170-9.040), a higher educational level (college and above: OR = 7.598; 95% CI: 2.244-25.732) or children with poor healthy conditions (poor: OR = 6.864; 95% CI: 2.212-21.302) have much more negative perception of air quality. On the community level, industrial facilities, vehicles and city construction have major effects on parents' perception of air quality. Our investigation provides baseline information for environmental policy researchers and makers regarding the public's perception and expectation of air quality and the benefits to the environmental policy completing and enforcing. PMID:27187432

  16. Full-Reference Image Quality Assessment with Linear Combination of Genetically Selected Quality Measures

    PubMed Central

    2016-01-01

    Information carried by an image can be distorted due to different image processing steps introduced by different electronic means of storage and communication. Therefore, development of algorithms which can automatically assess a quality of the image in a way that is consistent with human evaluation is important. In this paper, an approach to image quality assessment (IQA) is proposed in which the quality of a given image is evaluated jointly by several IQA approaches. At first, in order to obtain such joint models, an optimisation problem of IQA measures aggregation is defined, where a weighted sum of their outputs, i.e., objective scores, is used as the aggregation operator. Then, the weight of each measure is considered as a decision variable in a problem of minimisation of root mean square error between obtained objective scores and subjective scores. Subjective scores reflect ground-truth and involve evaluation of images by human observers. The optimisation problem is solved using a genetic algorithm, which also selects suitable measures used in aggregation. Obtained multimeasures are evaluated on four largest widely used image benchmarks and compared against state-of-the-art full-reference IQA approaches. Results of comparison reveal that the proposed approach outperforms other competing measures. PMID:27341493

  17. Full-Reference Image Quality Assessment with Linear Combination of Genetically Selected Quality Measures.

    PubMed

    Oszust, Mariusz

    2016-01-01

    Information carried by an image can be distorted due to different image processing steps introduced by different electronic means of storage and communication. Therefore, development of algorithms which can automatically assess a quality of the image in a way that is consistent with human evaluation is important. In this paper, an approach to image quality assessment (IQA) is proposed in which the quality of a given image is evaluated jointly by several IQA approaches. At first, in order to obtain such joint models, an optimisation problem of IQA measures aggregation is defined, where a weighted sum of their outputs, i.e., objective scores, is used as the aggregation operator. Then, the weight of each measure is considered as a decision variable in a problem of minimisation of root mean square error between obtained objective scores and subjective scores. Subjective scores reflect ground-truth and involve evaluation of images by human observers. The optimisation problem is solved using a genetic algorithm, which also selects suitable measures used in aggregation. Obtained multimeasures are evaluated on four largest widely used image benchmarks and compared against state-of-the-art full-reference IQA approaches. Results of comparison reveal that the proposed approach outperforms other competing measures. PMID:27341493

  18. Improving Image Quality of Bronchial Arteries with Virtual Monochromatic Spectral CT Images

    PubMed Central

    Ma, Guangming; He, Taiping; Yu, Yong; Duan, Haifeng; Yang, Chuangbo

    2016-01-01

    Objective To evaluate the clinical value of using monochromatic images in spectral CT pulmonary angiography to improve image quality of bronchial arteries. Methods We retrospectively analyzed the chest CT images of 38 patients who underwent contrast-enhanced spectral CT. These images included a set of 140kVp polychromatic images and the default 70keV monochromatic images. Using the standard Gemstone Spectral Imaging (GSI) viewer on an advanced workstation (AW4.6,GE Healthcare), an optimal energy level (in keV) for obtaining the best contrast-to-noise ratio (CNR) for the artery could be automatically obtained. The signal-to-noise ratio (SNR), CNR and objective image quality score (1–5) for these 3 image sets (140kVp, 70keV and optimal energy level) were obtained and, statistically compared. The image quality score consistency between the two observers was also evaluated using Kappa test. Results The optimal energy levels for obtaining the best CNR were 62.58±2.74keV.SNR and CNR from the 140kVp polychromatic, 70keV and optimal keV monochromatic images were (16.44±5.85, 13.24±5.52), (20.79±7.45, 16.69±6.27) and (24.9±9.91, 20.53±8.46), respectively. The corresponding subjective image quality scores were 1.97±0.82, 3.24±0.75, and 4.47±0.60. SNR, CNR and subjective scores had significant difference among groups (all p<0.001). The optimal keV monochromatic images were superior to the 70keV monochromatic and 140kVp polychromatic images, and there was high agreement between the two observers on image quality score (kappa>0.80). Conclusions Virtual monochromatic images at approximately 63keV in dual-energy spectral CT pulmonary angiography yielded the best CNR and highest diagnostic confidence for imaging bronchial arteries. PMID:26967737

  19. Image quality specification and maintenance for airborne SAR

    NASA Astrophysics Data System (ADS)

    Clinard, Mark S.

    2004-08-01

    Specification, verification, and maintenance of image quality over the lifecycle of an operational airborne SAR begin with the specification for the system itself. Verification of image quality-oriented specification compliance can be enhanced by including a specification requirement that a vendor provide appropriate imagery at the various phases of the system life cycle. The nature and content of the imagery appropriate for each stage of the process depends on the nature of the test, the economics of collection, and the availability of techniques to extract the desired information from the data. At the earliest lifecycle stages, Concept and Technology Development (CTD) and System Development and Demonstration (SDD), the test set could include simulated imagery to demonstrate the mathematical and engineering concepts being implemented thus allowing demonstration of compliance, in part, through simulation. For Initial Operational Test and Evaluation (IOT&E), imagery collected from precisely instrumented test ranges and targets of opportunity consisting of a priori or a posteriori ground-truthed cultural and natural features are of value to the analysis of product quality compliance. Regular monitoring of image quality is possible using operational imagery and automated metrics; more precise measurements can be performed with imagery of instrumented scenes, when available. A survey of image quality measurement techniques is presented along with a discussion of the challenges of managing an airborne SAR program with the scarce resources of time, money, and ground-truthed data. Recommendations are provided that should allow an improvement in the product quality specification and maintenance process with a minimal increase in resource demands on the customer, the vendor, the operational personnel, and the asset itself.

  20. Imaging quality automated measurement of image intensifier based on orthometric phase-shifting gratings.

    PubMed

    Sun, Song; Cao, Yiping

    2016-06-01

    A method for automatically measuring the imaging quality parameters of an image intensifier based on orthometric phase-shifting gratings (OPSG) is proposed. Two sets of phase-shifting gratings, one with a fringe direction at 45° and the other at 135°, are successively projected onto the input port of the image intensifier, and the corresponding deformed patterns modulated by the measured image intensifier on its output port are captured with a CCD camera. Two phases are retrieved from these two sets of deformed patterns by a phase-measuring algorithm. By building the relationship between these retrieved phases, the referential fringe period can be determined accurately. Meanwhile, the distorted phase distribution introduced by the image intensifier can also be efficiently separated wherein the subtle imaging quality information can be further decomposed. Subsequently, the magnification of the image intensifier is successfully measured by fringe period self-calibration. The experimental results have shown the feasibility of the proposed method, which can automatically measure the multiple imaging quality parameters of an image intensifier without human intervention. PMID:27411191

  1. Imaging through turbid media via sparse representation: imaging quality comparison of three projection matrices

    NASA Astrophysics Data System (ADS)

    Shao, Xiaopeng; Li, Huijuan; Wu, Tengfei; Dai, Weijia; Bi, Xiangli

    2015-05-01

    The incident light will be scattered away due to the inhomogeneity of the refractive index in many materials which will greatly reduce the imaging depth and degrade the imaging quality. Many exciting methods have been presented in recent years for solving this problem and realizing imaging through a highly scattering medium, such as the wavefront modulation technique and reconstruction technique. The imaging method based on compressed sensing (CS) theory can decrease the computational complexity because it doesn't require the whole speckle pattern to realize reconstruction. One of the key premises of this method is that the object is sparse or can be sparse representation. However, choosing a proper projection matrix is very important to the imaging quality. In this paper, we analyzed that the transmission matrix (TM) of a scattering medium obeys circular Gaussian distribution, which makes it possible that a scattering medium can be used as the measurement matrix in the CS theory. In order to verify the performance of this method, a whole optical system is simulated. Various projection matrices are introduced to make the object sparse, including the fast Fourier transform (FFT) basis, the discrete cosine transform (DCT) basis and the discrete wavelet transform (DWT) basis, the imaging performances of each of which are compared comprehensively. Simulation results show that for most targets, applying the discrete wavelet transform basis will obtain an image in good quality. This work can be applied to biomedical imaging and used to develop real-time imaging through highly scattering media.

  2. High Fidelity Images--How They Affect Learning.

    ERIC Educational Resources Information Center

    Kwinn, Ann

    1997-01-01

    Discusses the use of graphics in instruction and concludes that cosmetic and motivational graphics can be more realistic and detailed for affective goals, while schematic graphics may be best for the more cognitive functions of focusing attention and presenting actual content. Domains of learning, mental models, and visualization are examined.…

  3. Wash operations affect water quality and packaged fresh-cut romaine lettuce quality and microbial growth

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Washing during the preparation of fresh-cut produce is an important step to maintaining the quality and safety of the finished products. It is often the only step aimed at reducing microbial populations and removing tissue fluids from cut produce. However, little is known about the effects of washi...

  4. Damage and quality assessment in wheat by NIR hyperspectral imaging

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Fusarium head blight is a fungal disease that affects the world's small grains, such as wheat and barley. Attacking the spikelets during development, the fungus causes a reduction of yield and grain of poorer processing quality. It also is a health concern because of the secondary metabolite, deoxyn...

  5. Comprehensive quality assurance phantom for cardiovascular imaging systems

    NASA Astrophysics Data System (ADS)

    Lin, Pei-Jan P.

    1998-07-01

    With the advent of high heat loading capacity x-ray tubes, high frequency inverter type generators, and the use of spectral shaping filters, the automatic brightness/exposure control (ABC) circuit logic employed in the new generation of angiographic imaging equipment has been significantly reprogrammed. These new angiographic imaging systems are designed to take advantage of the power train capabilities to yield higher contrast images while maintaining, or lower, the patient exposure. Since the emphasis of the imaging system design has been significantly altered, the system performance parameters one is interested and the phantoms employed for the quality assurance must also change in order to properly evaluate the imaging capability of the cardiovascular imaging systems. A quality assurance (QA) phantom has been under development in this institution and was submitted to various interested organizations such as American Association of Physicists in Medicine (AAPM), Society for Cardiac Angiography & Interventions (SCA&I), and National Electrical Manufacturers Association (NEMA) for their review and input. At the same time, in an effort to establish a unified standard phantom design for the cardiac catheterization laboratories (CCL), SCA&I and NEMA have formed a joint work group in early 1997 to develop a suitable phantom. The initial QA phantom design has since been accepted to serve as the base phantom by the SCA&I- NEMA Joint Work Group (JWG) from which a comprehensive QA Phantom is being developed.

  6. Investigation of grid performance using simple image quality tests

    PubMed Central

    Bor, Dogan; Birgul, Ozlem; Onal, Umran; Olgar, Turan

    2016-01-01

    Antiscatter grids improve the X-ray image contrast at a cost of patient radiation doses. The choice of appropriate grid or its removal requires a good knowledge of grid characteristics, especially for pediatric digital imaging. The aim of this work is to understand the relation between grid performance parameters and some numerical image quality metrics for digital radiological examinations. The grid parameters such as bucky factor (BF), selectivity (Σ), Contrast improvement factor (CIF), and signal-to-noise improvement factor (SIF) were determined following the measurements of primary, scatter, and total radiations with a digital fluoroscopic system for the thicknesses of 5, 10, 15, 20, and 25 cm polymethyl methacrylate blocks at the tube voltages of 70, 90, and 120 kVp. Image contrast for low- and high-contrast objects and high-contrast spatial resolution were measured with simple phantoms using the same scatter thicknesses and tube voltages. BF and SIF values were also calculated from the images obtained with and without grids. The correlation coefficients between BF values obtained using two approaches (grid parameters and image quality metrics) were in good agreement. Proposed approach provides a quick and practical way of estimating grid performance for different digital fluoroscopic examinations. PMID:27051166

  7. A study of image quality for radar image processing. [synthetic aperture radar imagery

    NASA Technical Reports Server (NTRS)

    King, R. W.; Kaupp, V. H.; Waite, W. P.; Macdonald, H. C.

    1982-01-01

    Methods developed for image quality metrics are reviewed with focus on basic interpretation or recognition elements including: tone or color; shape; pattern; size; shadow; texture; site; association or context; and resolution. Seven metrics are believed to show promise as a way of characterizing the quality of an image: (1) the dynamic range of intensities in the displayed image; (2) the system signal-to-noise ratio; (3) the system spatial bandwidth or bandpass; (4) the system resolution or acutance; (5) the normalized-mean-square-error as a measure of geometric fidelity; (6) the perceptual mean square error; and (7) the radar threshold quality factor. Selective levels of degradation are being applied to simulated synthetic radar images to test the validity of these metrics.

  8. [An improved medical image fusion algorithm and quality evaluation].

    PubMed

    Chen, Meiling; Tao, Ling; Qian, Zhiyu

    2009-08-01

    Medical image fusion is of very important value for application in medical image analysis and diagnosis. In this paper, the conventional method of wavelet fusion is improved,so a new algorithm of medical image fusion is presented and the high frequency and low frequency coefficients are studied respectively. When high frequency coefficients are chosen, the regional edge intensities of each sub-image are calculated to realize adaptive fusion. The choice of low frequency coefficient is based on the edges of images, so that the fused image preserves all useful information and appears more distinctly. We apply the conventional and the improved fusion algorithms based on wavelet transform to fuse two images of human body and also evaluate the fusion results through a quality evaluation method. Experimental results show that this algorithm can effectively retain the details of information on original images and enhance their edge and texture features. This new algorithm is better than the conventional fusion algorithm based on wavelet transform. PMID:19813594

  9. Evaluation of image quality of a new CCD-based system for chest imaging

    NASA Astrophysics Data System (ADS)

    Sund, Patrik; Kheddache, Susanne; Mansson, Lars G.; Bath, Magnus; Tylen, Ulf

    2000-04-01

    The Imix radiography system (Qy Imix Ab, Finland)consists of an intensifying screen, optics, and a CCD camera. An upgrade of this system (Imix 2000) with a red-emitting screen and new optics has recently been released. The image quality of Imix (original version), Imix 200, and two storage-phosphor systems, Fuji FCR 9501 and Agfa ADC70 was evaluated in physical terms (DQE) and with visual grading of the visibility of anatomical structures in clinical images (141 kV). PA chest images of 50 healthy volunteers were evaluated by experienced radiologists. All images were evaluated on Siemens Simomed monitors, using the European Quality Criteria. The maximum DQE values for Imix, Imix 2000, Agfa and Fuji were 11%, 14%, 17% and 19%, respectively (141kV, 5μGy). Using the visual grading, the observers rated the systems in the following descending order. Fuji, Imix 2000, Agfa, and Imix. Thus, the upgrade to Imix 2000 resulted in higher DQE values and a significant improvement in clinical image quality. The visual grading agrees reasonably well with the DQE results; however, Imix 2000 received a better score than what could be expected from the DQE measurements. Keywords: CCD Technique, Chest Imaging, Digital Radiography, DQE, Image Quality, Visual Grading Analysis

  10. Impact of the optical depth of field on cytogenetic image quality.

    PubMed

    Qiu, Yuchen; Chen, Xiaodong; Li, Yuhua; Zheng, Bin; Li, Shibo; Chen, Wei R; Liu, Hong

    2012-09-01

    In digital pathology, clinical specimen slides are converted into digital images by microscopic image scanners. Since random vibration and mechanical drifting are unavoidable on even high-precision moving stages, the optical depth of field (DOF) of microscopic systems may affect image quality, in particular when using an objective lens with high magnification power. The DOF of a microscopic system was theoretically analyzed and experimentally validated using standard resolution targets under 60× dry and 100× oil objective lenses, respectively. Then cytogenetic samples were imaged at in-focused and off-focused states to analyze the impact of DOF on the acquired image qualities. For the investigated system equipped with the 60× dry and 100× oil objective lenses, the theoretical estimation of the DOF are 0.855 μm and 0.703 μm, and the measured DOF are 3.0 μm and 1.8 μm, respectively. The observation reveals that the chromosomal bands of metaphase cells are distinguishable when images are acquired up to approximately 1.5 μm or 1 μm out of focus using the 60× dry and 100× oil objective lenses, respectively. The results of this investigation provide important designing trade-off parameters to optimize the digital microscopic image scanning systems in the future. PMID:23085918

  11. No-reference image quality assessment in the spatial domain.

    PubMed

    Mittal, Anish; Moorthy, Anush Krishna; Bovik, Alan Conrad

    2012-12-01

    We propose a natural scene statistic-based distortion-generic blind/no-reference (NR) image quality assessment (IQA) model that operates in the spatial domain. The new model, dubbed blind/referenceless image spatial quality evaluator (BRISQUE) does not compute distortion-specific features, such as ringing, blur, or blocking, but instead uses scene statistics of locally normalized luminance coefficients to quantify possible losses of "naturalness" in the image due to the presence of distortions, thereby leading to a holistic measure of quality. The underlying features used derive from the empirical distribution of locally normalized luminances and products of locally normalized luminances under a spatial natural scene statistic model. No transformation to another coordinate frame (DCT, wavelet, etc.) is required, distinguishing it from prior NR IQA approaches. Despite its simplicity, we are able to show that BRISQUE is statistically better than the full-reference peak signal-to-noise ratio and the structural similarity index, and is highly competitive with respect to all present-day distortion-generic NR IQA algorithms. BRISQUE has very low computational complexity, making it well suited for real time applications. BRISQUE features may be used for distortion-identification as well. To illustrate a new practical application of BRISQUE, we describe how a nonblind image denoising algorithm can be augmented with BRISQUE in order to perform blind image denoising. Results show that BRISQUE augmentation leads to performance improvements over state-of-the-art methods. A software release of BRISQUE is available online: http://live.ece.utexas.edu/research/quality/BRISQUE_release.zip for public use and evaluation. PMID:22910118

  12. TL dosimetry for quality control of CR mammography imaging systems

    NASA Astrophysics Data System (ADS)

    Gaona, E.; Nieto, J. A.; Góngora, J. A. I. D.; Arreola, M.; Enríquez, J. G. F.

    The aim of this work is to estimate the average glandular dose with thermoluminescent (TL) dosimetry and comparison with quality imaging in computed radiography (CR) mammography. For a measuring dose, the Food and Drug Administration (FDA) and the American College of Radiology (ACR) use a phantom, so that dose and image quality are assessed with the same test object. The mammography is a radiological image to visualize early biological manifestations of breast cancer. Digital systems have two types of image-capturing devices, full field digital mammography (FFDM) and CR mammography. In Mexico, there are several CR mammography systems in clinical use, but only one system has been approved for use by the FDA. Mammography CR uses a photostimulable phosphor detector (PSP) system. Most CR plates are made of 85% BaFBr and 15% BaFI doped with europium (Eu) commonly called barium flourohalideE We carry out an exploratory survey of six CR mammography units from three different manufacturers and six dedicated X-ray mammography units with fully automatic exposure. The results show three CR mammography units (50%) have a dose greater than 3.0 mGy without demonstrating improved image quality. The differences between doses averages from TLD system and dosimeter with ionization chamber are less than 10%. TLD system is a good option for average glandular dose measurement for X-rays with a HVL (0.35-0.38 mmAl) and kVp (24-26) used in quality control procedures with ACR Mammography Accreditation Phantom.

  13. Image-based Tissue Distribution Modeling for Skeletal Muscle Quality Characterization

    PubMed Central

    Fishbein, K. W.; Moore, A. Z.; Spencer, R. G.; Ferrucci, L.

    2016-01-01

    The identification and characterization of regional body tissues is essential to understand changes that occur with aging and age-related metabolic diseases such as diabetes and obesity and how these diseases affect trajectories of health and functional status. Imaging technologies are frequently used to derive volumetric, area, and density measurements of different tissues. Despite the significance and direct applicability of automated tissue quantification and characterization techniques, these topics have remained relatively under-explored in the medical image analysis literature. We present a method for identification and characterization of muscle and adipose tissue in the mid-thigh region using MRI. We propose an image-based muscle quality prediction technique that estimates tissue-specific probability density models and their eigenstructures in the joint domain of water- and fat-suppressed voxel signal intensities along with volumetric and intensity-based tissue characteristics computed during the quantification stage. We evaluated the predictive capability of our approach against reference biomechanical muscle quality measurements using statistical tests and classification performance experiments. The reference standard for muscle quality is defined as the ratio of muscle strength to muscle mass. The results show promise for the development of non-invasive image-based muscle quality descriptors. PMID:26336111

  14. Positive affect modulates activity in the visual cortex to images of high calorie foods.

    PubMed

    Killgore, William D S; Yurgelun-Todd, Deborah A

    2007-05-01

    Activity within the visual cortex can be influenced by the emotional salience of a stimulus, but it is not clear whether such cortical activity is modulated by the affective status of the individual. This study used functional magnetic resonance imaging (fMRI) to examine the relationship between affect ratings on the Positive and Negative Affect Schedule and activity within the occipital cortex of 13 normal-weight women while viewing images of high calorie and low calorie foods. Regression analyses revealed that when participants viewed high calorie foods, Positive Affect correlated significantly with activity within the lingual gyrus and calcarine cortex, whereas Negative Affect was unrelated to visual cortex activity. In contrast, during presentations of low calorie foods, affect ratings, regardless of valence, were unrelated to occipital cortex activity. These findings suggest a mechanism whereby positive affective state may affect the early stages of sensory processing, possibly influencing subsequent perceptual experience of a stimulus. PMID:17464782

  15. Image Quality Analysis of Various Gastrointestinal Endoscopes: Why Image Quality Is a Prerequisite for Proper Diagnostic and Therapeutic Endoscopy

    PubMed Central

    Ko, Weon Jin; An, Pyeong; Ko, Kwang Hyun; Hahm, Ki Baik; Hong, Sung Pyo

    2015-01-01

    Arising from human curiosity in terms of the desire to look within the human body, endoscopy has undergone significant advances in modern medicine. Direct visualization of the gastrointestinal (GI) tract by traditional endoscopy was first introduced over 50 years ago, after which fairly rapid advancement from rigid esophagogastric scopes to flexible scopes and high definition videoscopes has occurred. In an effort towards early detection of precancerous lesions in the GI tract, several high-technology imaging scopes have been developed, including narrow band imaging, autofocus imaging, magnified endoscopy, and confocal microendoscopy. However, these modern developments have resulted in fundamental imaging technology being skewed towards red-green-blue and this technology has obscured the advantages of other endoscope techniques. In this review article, we have described the importance of image quality analysis using a survey to consider the diversity of endoscope system selection in order to better achieve diagnostic and therapeutic goals. The ultimate aims can be achieved through the adoption of modern endoscopy systems that obtain high image quality. PMID:26473119

  16. Impact of contact lens zone geometry and ocular optics on bifocal retinal image quality

    PubMed Central

    Bradley, Arthur; Nam, Jayoung; Xu, Renfeng; Harman, Leslie; Thibos, Larry

    2014-01-01

    Purpose To examine the separate and combined influences of zone geometry, pupil size, diffraction, apodisation and spherical aberration on the optical performance of concentric zonal bifocals. Methods Zonal bifocal pupil functions representing eye + ophthalmic correction were defined by interleaving wavefronts from separate optical zones of the bifocal. A two-zone design (a central circular inner zone surrounded by an annular outer-zone which is bounded by the pupil) and a five-zone design (a central small circular zone surrounded by four concentric annuli) were configured with programmable zone geometry, wavefront phase and pupil transmission characteristics. Using computational methods, we examined the effects of diffraction, Stiles Crawford apodisation, pupil size and spherical aberration on optical transfer functions for different target distances. Results Apodisation alters the relative weighting of each zone, and thus the balance of near and distance optical quality. When spherical aberration is included, the effective distance correction, add power and image quality depend on zone-geometry and Stiles Crawford Effect apodisation. When the outer zone width is narrow, diffraction limits the available image contrast when focused, but as pupil dilates and outer zone width increases, aberrations will limit the best achievable image quality. With two-zone designs, balancing near and distance image quality is not achieved with equal area inner and outer zones. With significant levels of spherical aberration, multi-zone designs effectively become multifocals. Conclusion Wave optics and pupil varying ocular optics significantly affect the imaging capabilities of different optical zones of concentric bifocals. With two-zone bifocal designs, diffraction, pupil apodisation spherical aberration, and zone size influence both the effective add power and the pupil size required to balance near and distance image quality. Five-zone bifocal designs achieve a high degree of

  17. How much image noise can be added in cardiac x-ray imaging without loss in perceived image quality?

    NASA Astrophysics Data System (ADS)

    Gislason-Lee, Amber J.; Kumcu, Asli; Kengyelics, Stephen M.; Rhodes, Laura A.; Davies, Andrew G.

    2015-03-01

    Dynamic X-ray imaging systems are used for interventional cardiac procedures to treat coronary heart disease. X-ray settings are controlled automatically by specially-designed X-ray dose control mechanisms whose role is to ensure an adequate level of image quality is maintained with an acceptable radiation dose to the patient. Current commonplace dose control designs quantify image quality by performing a simple technical measurement directly from the image. However, the utility of cardiac X-ray images is in their interpretation by a cardiologist during an interventional procedure, rather than in a technical measurement. With the long term goal of devising a clinically-relevant image quality metric for an intelligent dose control system, we aim to investigate the relationship of image noise with clinical professionals' perception of dynamic image sequences. Computer-generated noise was added, in incremental amounts, to angiograms of five different patients selected to represent the range of adult cardiac patient sizes. A two alternative forced choice staircase experiment was used to determine the amount of noise which can be added to a patient image sequences without changing image quality as perceived by clinical professionals. Twenty-five viewing sessions (five for each patient) were completed by thirteen observers. Results demonstrated scope to increase the noise of cardiac X-ray images by up to 21% +/- 8% before it is noticeable by clinical professionals. This indicates a potential for 21% radiation dose reduction since X-ray image noise and radiation dose are directly related; this would be beneficial to both patients and personnel.

  18. Study on classification of pork quality using hyperspectral imaging technique

    NASA Astrophysics Data System (ADS)

    Zeng, Shan; Bai, Jun; Wang, Haibin

    2015-12-01

    The relative problems' research of chilled meat, thawed meat and spoiled meat discrimination by hyperspectral image technique were proposed, such the section of feature wavelengths, et al. First, based on 400 ~ 1000nm range hyperspectral image data of testing pork samples, by K-medoids clustering algorithm based on manifold distance, we select 30 important wavelengths from 753 wavelengths, and thus select 8 feature wavelengths (454.4, 477.5, 529.3, 546.8, 568.4, 580.3, 589.9 and 781.2nm) based on the discrimination value. Then 8 texture features of each image under 8 feature wavelengths were respectively extracted by two-dimensional Gabor wavelets transform as pork quality feature. Finally, we build a pork quality classification model using the fuzzy C-mean clustering algorithm. Through the experiment of extracting feature wavelengths, we found that although the hyperspectral images between adjacent bands have a strong linear correlation, they show a significant non-linear manifold relationship from the entire band. K-medoids clustering algorithm based on manifold distance used in this paper for selecting the characteristic wavelengths, which is more reasonable than traditional principal component analysis (PCA). Through the classification result, we conclude that hyperspectral imaging technology can distinguish among chilled meat, thawed meat and spoiled meat accurately.

  19. Automated quality assurance for image-guided radiation therapy.

    PubMed

    Schreibmann, Eduard; Elder, Eric; Fox, Tim

    2009-01-01

    The use of image-guided patient positioning requires fast and reliable Quality Assurance (QA) methods to ensure the megavoltage (MV) treatment beam coincides with the integrated kilovoltage (kV) or volumetric cone-beam CT (CBCT) imaging and guidance systems. Current QA protocol is based on visually observing deviations of certain features in acquired kV in-room treatment images such as markers, distances, or HU values from phantom specifications. This is a time-consuming and subjective task because these features are identified by human operators. The method implemented in this study automated an IGRT QA protocol by using specific image processing algorithms that rigorously detected phantom features and performed all measurements involved in a classical QA protocol. The algorithm was tested on four different IGRT QA phantoms. Image analysis algorithms were able to detect QA features with the same accuracy as the manual approach but significantly faster. All described tests were performed in a single procedure, with acquisition of the images taking approximately 5 minutes, and the automated software analysis taking less than 1 minute. The study showed that the automated image analysis based procedure may be used as a daily QA procedure because it is completely automated and uses a single phantom setup. PMID:19223842

  20. DES exposure checker: Dark Energy Survey image quality control crowdsourcer

    NASA Astrophysics Data System (ADS)

    Melchior, Peter; Sheldon, Erin; Drlica-Wagner, Alex; Rykoff, Eli S.

    2015-11-01

    DES exposure checker renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes, thus allowing image quality control for the Dark Energy Survey to be crowdsourced through its web application. Users can also generate custom labels to help identify previously unknown problem classes; generated reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. These problem reports allow rapid correction of artifacts that otherwise may be too subtle or infrequent to be recognized.

  1. Exploring V1 by modeling the perceptual quality of images.

    PubMed

    Zhang, Fan; Jiang, Wenfei; Autrusseau, Florent; Lin, Weisi

    2014-01-01

    We propose an image quality model based on phase and amplitude differences between a reference and a distorted image. The proposed model is motivated by the fact that polar representations can separate visual information in a more independent and efficient manner than Cartesian representations in the primary visual cortex (V1). We subsequently estimate the model parameters from a large subjective data set using maximum likelihood methods. By comparing the various model hypotheses on the functional form about the phase and amplitude, we find that: (a) discrimination of visual orientation is important for quality assessment and yet a coarse level of such discrimination seems sufficient; and (b) a product-based amplitude-phase combination before pooling is effective, suggesting an interesting viewpoint about the functional structure of the simple cells and complex cells in V1. PMID:24464165

  2. Image-inpainting and quality-guided phase unwrapping algorithm.

    PubMed

    Meng, Lei; Fang, Suping; Yang, Pengcheng; Wang, Leijie; Komori, Masaharu; Kubo, Aizoh

    2012-05-01

    For the wrapped phase map with regional abnormal fringes, a new phase unwrapping algorithm that combines the image-inpainting theory and the quality-guided phase unwrapping algorithm is proposed. First, by applying a threshold to the modulation map, the valid region (i.e., the interference region) is divided into the doubtful region (called the target region during the inpainting period) and the reasonable one (the source region). The wrapped phase of the doubtful region is thought to be unreliable, and the data are abandoned temporarily. Using the region-filling image-inpainting method, the blank target region is filled with new data, while nothing is changed in the source region. A new wrapped phase map is generated, and then it is unwrapped with the quality-guided phase unwrapping algorithm. Finally, a postprocessing operation is proposed for the final result. Experimental results have shown that the performance of the proposed algorithm is effective. PMID:22614426

  3. A technique for multi-dimensional optimization of radiation dose, contrast dose, and image quality in CT imaging

    NASA Astrophysics Data System (ADS)

    Sahbaee, Pooyan; Abadi, Ehsan; Sanders, Jeremiah; Becchetti, Marc; Zhang, Yakun; Agasthya, Greeshma; Segars, Paul; Samei, Ehsan

    2016-03-01

    The purpose of this study was to substantiate the interdependency of image quality, radiation dose, and contrast material dose in CT towards the patient-specific optimization of the imaging protocols. The study deployed two phantom platforms. First, a variable sized phantom containing an iodinated insert was imaged on a representative CT scanner at multiple CTDI values. The contrast and noise were measured from the reconstructed images for each phantom diameter. Linearly related to iodine-concentration, contrast to noise ratio (CNR), was calculated for different iodine-concentration levels. Second, the analysis was extended to a recently developed suit of 58 virtual human models (5D-XCAT) with added contrast dynamics. Emulating a contrast-enhanced abdominal image procedure and targeting a peak-enhancement in aorta, each XCAT phantom was "imaged" using a CT simulation platform. 3D surfaces for each patient/size established the relationship between iodine-concentration, dose, and CNR. The Sensitivity of Ratio (SR), defined as ratio of change in iodine-concentration versus dose to yield a constant change in CNR was calculated and compared at high and low radiation dose for both phantom platforms. The results show that sensitivity of CNR to iodine concentration is larger at high radiation dose (up to 73%). The SR results were highly affected by radiation dose metric; CTDI or organ dose. Furthermore, results showed that the presence of contrast material could have a profound impact on optimization results (up to 45%).

  4. High image quality sub 100 picosecond gated framing camera development

    SciTech Connect

    Price, R.H.; Wiedwald, J.D.

    1983-11-17

    A major challenge for laser fusion is the study of the symmetry and hydrodynamic stability of imploding fuel capsules. Framed x-radiographs of 10-100 ps duration, excellent image quality, minimum geometrical distortion (< 1%), dynamic range greater than 1000, and more than 200 x 200 pixels are required for this application. Recent progress on a gated proximity focused intensifier which meets these requirements is presented.

  5. Seasonal time and frequency of switchgrass harvest affects biomass yield and feedstock quality

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seasonal time of switchgrass (Panicum virgatum L.) harvest affects both yield and feedstock quality and there is interest in reducing harvest frequency to improve wildlife habitat value when using Conservation Reserve Program (CRP) land for biomass production. A field study in central Pennsylvania c...

  6. Marital Quality, Maternal Depressed Affect, Harsh Parenting, and Child Externalising in Hong Kong Chinese Families

    ERIC Educational Resources Information Center

    Chang, Lei; Lansford, Jennifer E.; Schwartz, David; Farver, Joann M.

    2004-01-01

    The present study used a family systems approach to examine harsh parenting, maternal depressed affect, and marital quality in relation to children's externalising behaviour problems in a sample of 158 Hong Kong primary school children. At two time points, peers and teachers provided ratings of children's externalising behaviours, and mothers…

  7. HVAC SYSTEMS AS EMISSION SOURCES AFFECTING INDOOR AIR QUALITY: A CRITICAL REVIEW

    EPA Science Inventory

    The paper discusses results of an evaluation of literature on heating, ventilating, and air-conditioning (HVAC) systems as contaminant emission sources that affect indoor air quality (IAQ). The various literature sources and methods for characterizing HVAC emission sources are re...

  8. WebCT--The Quasimoderating Effect of Perceived Affective Quality on an Extending Technology Acceptance Model

    ERIC Educational Resources Information Center

    Sanchez-Franco, Manuel J.

    2010-01-01

    Perceived affective quality is an attractive area of research in Information System. Specifically, understanding the intrinsic and extrinsic individual factors and interaction effects that influence Information and Communications Technology (ICT) acceptance and adoption--in higher education--continues to be a focal interest in learning research.…

  9. A Case Study Showing Parameters Affecting the Quality of Education: Faculty Perspective

    ERIC Educational Resources Information Center

    Kumari, Neeraj

    2014-01-01

    The study aims to examine the faculty members' perspective (age Wise, Gender Wise and Work Experience wise) of parameters affecting the quality of education in an affiliated Undergraduate Engineering Institution in Haryana. It is a descriptive type of research. The data has been collected with the help of 'Questionnaire Based Survey'. The sample…

  10. Factors Affecting Perceived Learning, Satisfaction, and Quality in the Online MBA: A Structural Equation Modeling Approach

    ERIC Educational Resources Information Center

    Sebastianelli, Rose; Swift, Caroline; Tamimi, Nabil

    2015-01-01

    The authors examined how six factors related to content and interaction affect students' perceptions of learning, satisfaction, and quality in online master of business administration (MBA) courses. They developed three scale items to measure each factor. Using survey data from MBA students at a private university, the authors estimated structural…

  11. Incorporating detection tasks into the assessment of CT image quality

    NASA Astrophysics Data System (ADS)

    Scalzetti, E. M.; Huda, W.; Ogden, K. M.; Khan, M.; Roskopf, M. L.; Ogden, D.

    2006-03-01

    The purpose of this study was to compare traditional and task dependent assessments of CT image quality. Chest CT examinations were obtained with a standard protocol for subjects participating in a lung cancer-screening project. Images were selected for patients whose weight ranged from 45 kg to 159 kg. Six ABR certified radiologists subjectively ranked these images using a traditional six-point ranking scheme that ranged from 1 (inadequate) to 6 (excellent). Three subtle diagnostic tasks were identified: (1) a lung section containing a sub-centimeter nodule of ground-glass opacity in an upper lung (2) a mediastinal section with a lymph node of soft tissue density in the mediastinum; (3) a liver section with a rounded low attenuation lesion in the liver periphery. Each observer was asked to estimate the probability of detecting each type of lesion in the appropriate CT section using a six-point scale ranging from 1 (< 10%) to 6 (> 90%). Traditional and task dependent measures of image quality were plotted as a function of patient weight. For the lung section, task dependent evaluations were very similar to those obtained using the traditional scoring scheme, but with larger inter-observer differences. Task dependent evaluations for the mediastinal section showed no obvious trend with subject weight, whereas there the traditional score decreased from ~4.9 for smaller subjects to ~3.3 for the larger subjects. Task dependent evaluations for the liver section showed a decreasing trend from ~4.1 for the smaller subjects to ~1.9 for the larger subjects, whereas the traditional evaluation had a markedly narrower range of scores. A task-dependent method of assessing CT image quality can be implemented with relative ease, and is likely to be more meaningful in the clinical setting.

  12. Radiometric Quality Evaluation of INSAT-3D Imager Data

    NASA Astrophysics Data System (ADS)

    Prakash, S.; Jindal, D.; Badal, N.; Kartikeyan, B.; Gopala Krishna, B.

    2014-11-01

    INSAT-3D is an advanced meteorological satellite of ISRO which acquires imagery in optical and infra-red (IR) channels for study of weather dynamics in Indian sub-continent region. In this paper, methodology of radiometric quality evaluation for Level-1 products of Imager, one of the payloads onboard INSAT-3D, is described. Firstly, overall visual quality of scene in terms of dynamic range, edge sharpness or modulation transfer function (MTF), presence of striping and other image artefacts is computed. Uniform targets in Desert and Sea region are identified for which detailed radiometric performance evaluation for IR channels is carried out. Mean brightness temperature (BT) of targets is computed and validated with independently generated radiometric references. Further, diurnal/seasonal trends in target BT values and radiometric uncertainty or sensor noise are studied. Results of radiometric quality evaluation over duration of eight months (January to August 2014) and comparison of radiometric consistency pre/post yaw flip of satellite are presented. Radiometric Analysis indicates that INSAT-3D images have high contrast (MTF > 0.2) and low striping effects. A bias of <4K is observed in the brightness temperature values of TIR-1 channel measured during January-August 2014 indicating consistent radiometric calibration. Diurnal and seasonal analysis shows that Noise equivalent differential temperature (NEdT) for IR channels is consistent and well within specifications.

  13. Beef quality parameters estimation using ultrasound and color images

    PubMed Central

    2015-01-01

    Background Beef quality measurement is a complex task with high economic impact. There is high interest in obtaining an automatic quality parameters estimation in live cattle or post mortem. In this paper we set out to obtain beef quality estimates from the analysis of ultrasound (in vivo) and color images (post mortem), with the measurement of various parameters related to tenderness and amount of meat: rib eye area, percentage of intramuscular fat and backfat thickness or subcutaneous fat. Proposal An algorithm based on curve evolution is implemented to calculate the rib eye area. The backfat thickness is estimated from the profile of distances between two curves that limit the steak and the rib eye, previously detected. A model base in Support Vector Regression (SVR) is trained to estimate the intramuscular fat percentage. A series of features extracted on a region of interest, previously detected in both ultrasound and color images, were proposed. In all cases, a complete evaluation was performed with different databases including: color and ultrasound images acquired by a beef industry expert, intramuscular fat estimation obtained by an expert using a commercial software, and chemical analysis. Conclusions The proposed algorithms show good results to calculate the rib eye area and the backfat thickness measure and profile. They are also promising in predicting the percentage of intramuscular fat. PMID:25734452

  14. How much image noise can be added in cardiac x-ray imaging without loss in perceived image quality?

    NASA Astrophysics Data System (ADS)

    Gislason-Lee, Amber J.; Kumcu, Asli; Kengyelics, Stephen M.; Brettle, David S.; Treadgold, Laura A.; Sivananthan, Mohan; Davies, Andrew G.

    2015-09-01

    Cardiologists use x-ray image sequences of the moving heart acquired in real-time to diagnose and treat cardiac patients. The amount of radiation used is proportional to image quality; however, exposure to radiation is damaging to patients and personnel. The amount by which radiation dose can be reduced without compromising patient care was determined. For five patient image sequences, increments of computer-generated quantum noise (white + colored) were added to the images, frame by frame using pixel-to-pixel addition, to simulate corresponding increments of dose reduction. The noise adding software was calibrated for settings used in cardiac procedures, and validated using standard objective and subjective image quality measurements. The degraded images were viewed next to corresponding original (not degraded) images in a two-alternative-forced-choice staircase psychophysics experiment. Seven cardiologists and five radiographers selected their preferred image based on visualization of the coronary arteries. The point of subjective equality, i.e., level of degradation where the observer could not perceive a difference between the original and degraded images, was calculated; for all patients the median was 33%±15% dose reduction. This demonstrates that a 33%±15% increase in image noise is feasible without being perceived, indicating potential for 33%±15% dose reduction without compromising patient care.

  15. A virtual image chain for perceived image quality of medical display

    NASA Astrophysics Data System (ADS)

    Marchessoux, Cédric; Jung, Jürgen

    2006-03-01

    This paper describes a virtual image chain for medical display (project VICTOR: granted in the 5th framework program by European commission). The chain starts from raw data of an image digitizer (CR, DR) or synthetic patterns and covers image enhancement (MUSICA by Agfa) and both display possibilities, hardcopy (film on viewing box) and softcopy (monitor). Key feature of the chain is a complete image wise approach. A first prototype is implemented in an object-oriented software platform. The display chain consists of several modules. Raw images are either taken from scanners (CR-DR) or from a pattern generator, in which characteristics of DR- CR systems are introduced by their MTF and their dose-dependent Poisson noise. The image undergoes image enhancement and comes to display. For soft display, color and monochrome monitors are used in the simulation. The image is down-sampled. The non-linear response of a color monitor is taken into account by the GOG or S-curve model, whereas the Standard Gray-Scale-Display-Function (DICOM) is used for monochrome display. The MTF of the monitor is applied on the image in intensity levels. For hardcopy display, the combination of film, printer, lightbox and viewing condition is modeled. The image is up-sampled and the DICOM-GSDF or a Kanamori Look-Up-Table is applied. An anisotropic model for the MTF of the printer is applied on the image in intensity levels. The density-dependent color (XYZ) of the hardcopy film is introduced by Look-Up-tables. Finally a Human Visual System Model is applied to the intensity images (XYZ in terms of cd/m2) in order to eliminate nonvisible differences. Comparison leads to visible differences, which are quantified by higher order image quality metrics. A specific image viewer is used for the visualization of the intensity image and the visual difference maps.

  16. Pleiades-Hr Innovative Techniques for Radiometric Image Quality Commissioning

    NASA Astrophysics Data System (ADS)

    Blanchet, G.; Lebeque, L.; Fourest, S.; Latry, C.; Porez-Nadal, F.; Lacherade, S.; Thiebaut, C.

    2012-07-01

    The first Pleiades-HR satellite, part of a constellation of two, has been launched on December 17, 2011. This satellite produces high resolution optical images. In order to achieve good image quality, Pleiades-HR should first undergo an important 6 month commissioning phase period. This phase consists in calibrating and assessing the radiometric and geometric image quality to offer the best images to end users. This new satellite has benefited from technology improvements in various fields which make it stand out from other Earth observation satellites. In particular, its best-in-class agility performance enables new calibration and assessment techniques. This paper is dedicated to presenting these innovative techniques that have been tested for the first time for the Pleiades- HR radiometric commissioning. Radiometric activities concern compression, absolute calibration, detector normalization, and refocusing operations, MTF (Modulation Transfer Function) assessment, signal-to-noise ratio (SNR) estimation, and tuning of the ground processing parameters. The radiometric performances of each activity are summarized in this paper.

  17. Image gathering and digital restoration for fidelity and visual quality

    NASA Technical Reports Server (NTRS)

    Huck, Friedrich O.; Alter-Gartenberg, Rachel; Rahman, Zia-Ur

    1991-01-01

    The fidelity and resolution of the traditional Wiener restorations given in the prevalent digital processing literature can be significantly improved when the transformations between the continuous and discrete representations in image gathering and display are accounted for. However, the visual quality of these improved restorations also is more sensitive to the defects caused by aliasing artifacts, colored noise, and ringing near sharp edges. In this paper, these visual defects are characterized, and methods for suppressing them are presented. It is demonstrated how the visual quality of fidelity-maximized images can be improved when (1) the image-gathering system is specifically designed to enhance the performance of the image-restoration algorithm, and (2) the Wiener filter is combined with interactive Gaussian smoothing, synthetic high edge enhancement, and nonlinear tone-scale transformation. The nonlinear transformation is used primarily to enhance the spatial details that are often obscurred when the normally wide dynamic range of natural radiance fields is compressed into the relatively narrow dynamic range of film and other displays.

  18. ECG-synchronized DSA exposure control: improved cervicothoracic image quality

    SciTech Connect

    Kelly, W.M.; Gould, R.; Norman, D.; Brant-Zawadzki, M.; Cox, L.

    1984-10-01

    An electrocardiogram (ECG)-synchronized x-ray exposure sequence was used to acquire digital subtraction angiographic (DSA) images during 13 arterial injection studies of the aortic arch or carotid bifurcations. These gated images were compared with matched ungated DSA images acquired using the same technical factors, contrast material volume, and patient positioning. Subjective assessments by five experienced observers of edge definition, vessel conspicuousness, and overall diagnostic quality showed overall preference for one of the two acquisition methods in 69% of cases studied. Of these, the ECG-synchronized exposure series were rated superior in 76%. These results, as well as the relatively simple and inexpensive modifications required, suggest that routine use of ECG exposure control can facilitate improved arterial DSA evaluations of suspected cervicothoracic vascular disease.

  19. Effects of characteristics of image quality in an immersive environment

    NASA Technical Reports Server (NTRS)

    Duh, Henry Been-Lirn; Lin, James J W.; Kenyon, Robert V.; Parker, Donald E.; Furness, Thomas A.

    2002-01-01

    Image quality issues such as field of view (FOV) and resolution are important for evaluating "presence" and simulator sickness (SS) in virtual environments (VEs). This research examined effects on postural stability of varying FOV, image resolution, and scene content in an immersive visual display. Two different scenes (a photograph of a fountain and a simple radial pattern) at two different resolutions were tested using six FOVs (30, 60, 90, 120, 150, and 180 deg.). Both postural stability, recorded by force plates, and subjective difficulty ratings varied as a function of FOV, scene content, and image resolution. Subjects exhibited more balance disturbance and reported more difficulty in maintaining posture in the wide-FOV, high-resolution, and natural scene conditions.

  20. Objective assessment of image quality. IV. Application to adaptive optics

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Devaney, Nicholas; Dainty, Christopher

    2008-01-01

    The methodology of objective assessment, which defines image quality in terms of the performance of specific observers on specific tasks of interest, is extended to temporal sequences of images with random point spread functions and applied to adaptive imaging in astronomy. The tasks considered include both detection and estimation, and the observers are the optimal linear discriminant (Hotelling observer) and the optimal linear estimator (Wiener). A general theory of first- and second-order spatiotemporal statistics in adaptive optics is developed. It is shown that the covariance matrix can be rigorously decomposed into three terms representing the effect of measurement noise, random point spread function, and random nature of the astronomical scene. Figures of merit are developed, and computational methods are discussed. PMID:17106464

  1. Image quality criteria for wide-field x-ray imaging applications

    NASA Astrophysics Data System (ADS)

    Thompson, Patrick L.; Harvey, James E.

    1999-10-01

    For staring, wide-field applications, such as a solar x-ray imager, the severe off-axis aberrations of the classical Wolter Type-I grazing incidence x-ray telescope design drastically limits the 'resolution' near the solar limb. A specification upon on-axis fractional encircled energy is thus not an appropriate image quality criterion for such wide-angle applications. A more meaningful image quality criterion would be a field-weighted-average measure of 'resolution.' Since surface scattering effects from residual optical fabrication errors are always substantial at these very short wavelengths, the field-weighted-average half- power radius is a far more appropriate measure of aerial resolution. If an ideal mosaic detector array is being used in the focal plane, the finite pixel size provides a practical limit to this system performance. Thus, the total number of aerial resolution elements enclosed by the operational field-of-view, expressed as a percentage of the n umber of ideal detector pixels, is a further improved image quality criterion. In this paper we describe the development of an image quality criterion for wide-field applications of grazing incidence x-ray telescopes which leads to a new class of grazing incidence designs described in a following companion paper.

  2. Does Magnetic Resonance Imaging Affect the Microleakage of Amalgam Restorations?

    PubMed Central

    Akgun, Ozlem Marti; Polat, Gunseli Guven; Turan Illca, Ahmet; Yildirim, Ceren; Demir, Pervin; Basak, Feridun

    2014-01-01

    Background: The effect of MRI on microleakage of amalgam restorations is an important health issue that should be considered. If MRI application causes increase of microleakage, amalgam fillings should be reassessed after MRI and replaced if necessary. Objectives: The aim of this study is to compare the effect of magnetic resonance imaging (MRI) on microleakage of class II bonded amalgam versus classical amalgam restorations. Materials and Methods: Class II cavities (3 mm width × 1.5 mm depth) with gingival margins ending 1 mm below the cementoenamel junction (CEJ) were prepared in 40 permanent molar teeth. The teeth were randomly divided into four groups. Cavities in the first and second groups were restored with dentin adhesive and amalgam (bonded amalgam), and those in the third and fourth groups with amalgam only. MRI was performed with the teeth specimens from the first and third groups. All specimens were then thermocycled at 5° to 55° C with a 30-second dwell time for 1000 cycles. The samples were then immersed in 0.5% methylene blue dye for 24 hours and sectioned longitudinally. Dye penetration at the occlusal and gingival margins was quantified by 15× stereomicroscopy. IBM SPSS Statistics ver. 21.0 (IBM Corp., Released 2012., IBM SPSS Statistics for Windows, Armonk, NY: IBM Corp.) and MS-Excel 2007 programs were used for statistical analyses and calculations. “nparLD” module was used for F2_LD_F1 design analysis at R program. P<0.05 was considered statistically significant. Results: In teeth with amalgam filling, there were no significant differences of occlusal and gingival surface microleakage after MRI exposure. Occlusal and gingival surface microleakages were also similar with and without MRI in teeth with bonded amalgam filling. Conclusions: The results of this study suggest that MRI does not increase microleakage of amalgam restorations. PMID:25763074

  3. A new algorithm for integrated image quality measurement based on wavelet transform and human visual system

    NASA Astrophysics Data System (ADS)

    Wang, Haihui

    2006-01-01

    An essential determinant of the value of digital images is their quality. Over the past years, there have been many attempts to develop models or metrics for image quality that incorporate elements of human visual sensitivity. However, there is no current standard and objective definition of spectral image quality. This paper proposes a reliable automatic method for objective image quality measurement by wavelet transform and Human visual system. This way the proposed measure differentiates between the random and signal-dependant distortion, which have different effects on human observer. Performance of the proposed quality measure is illustrated by examples involving images with different types of degradation. The technique provides a means to relate the quality of an image to the interpretation and quantification throughout the frequency range, in which the noise level is estimated for quality evaluation. The experimental results of using this method for image quality measurement exhibit good correlation to subjective visual quality assessments.

  4. Cross-layer Energy Optimization Under Image Quality Constraints for Wireless Image Transmissions.

    PubMed

    Yang, Na; Demirkol, Ilker; Heinzelman, Wendi

    2012-01-01

    Wireless image transmission is critical in many applications, such as surveillance and environment monitoring. In order to make the best use of the limited energy of the battery-operated cameras, while satisfying the application-level image quality constraints, cross-layer design is critical. In this paper, we develop an image transmission model that allows the application layer (e.g., the user) to specify an image quality constraint, and optimizes the lower layer parameters of transmit power and packet length, to minimize the energy dissipation in image transmission over a given distance. The effectiveness of this approach is evaluated by applying the proposed energy optimization to a reference ZigBee system and a WiFi system, and also by comparing to an energy optimization study that does not consider any image quality constraint. Evaluations show that our scheme outperforms the default settings of the investigated commercial devices and saves a significant amount of energy at middle-to-large transmission distances. PMID:23508852

  5. Characterization of image quality for 3D scatter-corrected breast CT images

    NASA Astrophysics Data System (ADS)

    Pachon, Jan H.; Shah, Jainil; Tornai, Martin P.

    2011-03-01

    The goal of this study was to characterize the image quality of our dedicated, quasi-monochromatic spectrum, cone beam breast imaging system under scatter corrected and non-scatter corrected conditions for a variety of breast compositions. CT projections were acquired of a breast phantom containing two concentric sets of acrylic spheres that varied in size (1-8mm) based on their polar position. The breast phantom was filled with 3 different concentrations of methanol and water, simulating a range of breast densities (0.79-1.0g/cc); acrylic yarn was sometimes included to simulate connective tissue of a breast. For each phantom condition, 2D scatter was measured for all projection angles. Scatter-corrected and uncorrected projections were then reconstructed with an iterative ordered subsets convex algorithm. Reconstructed image quality was characterized using SNR and contrast analysis, and followed by a human observer detection task for the spheres in the different concentric rings. Results show that scatter correction effectively reduces the cupping artifact and improves image contrast and SNR. Results from the observer study indicate that there was no statistical difference in the number or sizes of lesions observed in the scatter versus non-scatter corrected images for all densities. Nonetheless, applying scatter correction for differing breast conditions improves overall image quality.

  6. Visual instrument image quality metrics and the effects of coma and astigmatism.

    PubMed

    Mouroulis, P; Zhang, H P

    1992-01-01

    We examine subjective contrast and edge sharpness discrimination in the presence of different amounts of coma, astigmatism, and combinations of these two aberrations. We also examine the correlation between subjective results and objective image quality measures. These include the integral of the modulation transfer function (MTF) across the frequency range of interest (MTFa), the Strehl ratio, the variance of the wave-front aberration, and the radius of 84% encircled energy of the point-spread function (R84). For the target orientation that is most affected by the aberrations, we find that the MTFa and R84 give good correlation, while the Strehl ratio and the variance do not. In addition, we find that the MTFa correlates with subjective results for all target orientations. We discuss the implications of the results on the automated assessment of the image quality of visual instruments. PMID:1738049

  7. Assessing and improving cobalt-60 digital tomosynthesis image quality

    NASA Astrophysics Data System (ADS)

    Marsh, Matthew B.; Schreiner, L. John; Kerr, Andrew T.

    2014-03-01

    Image guidance capability is an important feature of modern radiotherapy linacs, and future cobalt-60 units will be expected to have similar capabilities. Imaging with the treatment beam is an appealing option, for reasons of simplicity and cost, but the dose needed to produce cone beam CT (CBCT) images in a Co-60 treatment beam is too high for this modality to be clinically useful. Digital tomosynthesis (DT) offers a quasi-3D image, of sufficient quality to identify bony anatomy or fiducial markers, while delivering a much lower dose than CBCT. A series of experiments were conducted on a prototype Co-60 cone beam imaging system to quantify the resolution, selectivity, geometric accuracy and contrast sensitivity of Co-60 DT. Although the resolution is severely limited by the penumbra cast by the ~2 cm diameter source, it is possible to identify high contrast objects on the order of 1 mm in width, and bony anatomy in anthropomorphic phantoms is clearly recognizable. Low contrast sensitivity down to electron density differences of 3% is obtained, for uniform features of similar thickness. The conventional shift-and-add reconstruction algorithm was compared to several variants of the Feldkamp-Davis-Kress filtered backprojection algorithm result. The Co-60 DT images were obtained with a total dose of 5 to 15 cGy each. We conclude that Co-60 radiotherapy units upgraded for modern conformal therapy could also incorporate imaging using filtered backprojection DT in the treatment beam. DT is a versatile and promising modality that would be well suited to image guidance requirements.

  8. The pupil's response to affective pictures: Role of image duration, habituation, and viewing mode.

    PubMed

    Snowden, Robert J; O'Farrell, Katherine R; Burley, Daniel; Erichsen, Jonathan T; Newton, Naomi V; Gray, Nicola S

    2016-08-01

    The pupil has been shown to be sensitive to the emotional content of stimuli. We examined this phenomenon by comparing fearful and neutral images carefully matched in the domains of luminance, image contrast, image color, and complexity of content. The pupil was more dilated after viewing affective pictures, and this effect was (a) shown to be independent of the presentation time of the images (from 100-3,000 ms), (b) not diminished by repeated presentations of the images, and (c) not affected by actively naming the emotion of the stimuli in comparison to passive viewing. Our results show that the emotional modulation of the pupil is present over a range of variables that typically vary from study to study (image duration, number of trials, free viewing vs. task), and encourages the use of pupillometry as a measure of emotional processing in populations where alternative techniques may not be appropriate. PMID:27172997

  9. SU-E-J-36: Comparison of CBCT Image Quality for Manufacturer Default Imaging Modes

    SciTech Connect

    Nelson, G

    2015-06-15

    Purpose CBCT is being increasingly used in patient setup for radiotherapy. Often the manufacturer default scan modes are used for performing these CBCT scans with the assumption that they are the best options. To quantitatively assess the image quality of these scan modes, all of the scan modes were tested as well as options with the reconstruction algorithm. Methods A CatPhan 504 phantom was scanned on a TrueBeam Linear Accelerator using the manufacturer scan modes (FSRT Head, Head, Image Gently, Pelvis, Pelvis Obese, Spotlight, & Thorax). The Head mode scan was then reconstructed multiple times with all filter options (Smooth, Standard, Sharp, & Ultra Sharp) and all Ring Suppression options (Disabled, Weak, Medium, & Strong). An open source ImageJ tool was created for analyzing the CatPhan 504 images. Results The MTF curve was primarily dictated by the voxel size and the filter used in the reconstruction algorithm. The filters also impact the image noise. The CNR was worst for the Image Gently mode, followed by FSRT Head and Head. The sharper the filter, the worse the CNR. HU varied significantly between scan modes. Pelvis Obese had lower than expected HU values than most while the Image Gently mode had higher than expected HU values. If a therapist tried to use preset window and level settings, they would not show the desired tissue for some scan modes. Conclusion Knowing the image quality of the set scan modes, will enable users to better optimize their setup CBCT. Evaluation of the scan mode image quality could improve setup efficiency and lead to better treatment outcomes.

  10. TU-B-19A-01: Image Registration II: TG132-Quality Assurance for Image Registration

    SciTech Connect

    Brock, K; Mutic, S

    2014-06-15

    AAPM Task Group 132 was charged with a review of the current approaches and solutions for image registration in radiotherapy and to provide recommendations for quality assurance and quality control of these clinical processes. As the results of image registration are always used as the input of another process for planning or delivery, it is important for the user to understand and document the uncertainty associate with the algorithm in general and the Result of a specific registration. The recommendations of this task group, which at the time of abstract submission are currently being reviewed by the AAPM, include the following components. The user should understand the basic image registration techniques and methods of visualizing image fusion. The disclosure of basic components of the image registration by commercial vendors is critical in this respect. The physicists should perform end-to-end tests of imaging, registration, and planning/treatment systems if image registration is performed on a stand-alone system. A comprehensive commissioning process should be performed and documented by the physicist prior to clinical use of the system. As documentation is important to the safe implementation of this process, a request and report system should be integrated into the clinical workflow. Finally, a patient specific QA practice should be established for efficient evaluation of image registration results. The implementation of these recommendations will be described and illustrated during this educational session. Learning Objectives: Highlight the importance of understanding the image registration techniques used in their clinic. Describe the end-to-end tests needed for stand-alone registration systems. Illustrate a comprehensive commissioning program using both phantom data and clinical images. Describe a request and report system to ensure communication and documentation. Demonstrate an clinically-efficient patient QA practice for efficient evaluation of image

  11. Miscanthus as a feedstock for fast-pyrolysis: does agronomic treatment affect quality?

    PubMed

    Hodgson, E M; Fahmi, R; Yates, N; Barraclough, T; Shield, I; Allison, G; Bridgwater, A V; Donnison, I S

    2010-08-01

    The objectives of the experiment were to assess the impact of nitrogen (N) and potassium (K) fertiliser application on the cell wall composition and fast-pyrolysis conversion quality of the commercially cultivated hybrid Miscanthus x giganteus. Five different fertiliser treatments were applied to mature Miscanthus plants which were sampled at five intervals over a growing season. The different fertiliser treatments produced significant variation in concentrations of cell wall components and ash within the biomass and affected the composition and quality of the resulting fast-pyrolysis liquids. The results indicated that application of high rates of N fertiliser had a negative effect on feedstock quality for this conversion pathway: reducing the proportion of cell wall components and increasing accumulation of ash in the harvested biomass. No exclusive effect of potassium fertiliser was observed. The low-N fertiliser treatment produced high quality, low ash-high lignin biomass most suitable as a feedstock for thermo-chemical conversion. PMID:20338753

  12. Color image quality in projection displays: a case study

    NASA Astrophysics Data System (ADS)

    Strand, Monica; Hardeberg, Jon Y.; Nussbaum, Peter

    2005-01-01

    Recently the use of projection displays has increased dramatically in different applications such as digital cinema, home theatre, and business and educational presentations. Even if the color image quality of these devices has improved significantly over the years, it is still a common situation for users of projection displays that the projected colors differ significantly from the intended ones. This study presented in this paper attempts to analyze the color image quality of a large set of projection display devices, particularly investigating the variations in color reproduction. As a case study, a set of 14 projectors (LCD and DLP technology) at Gjovik University College have been tested under four different conditions: dark and light room, with and without using an ICC-profile. To find out more about the importance of the illumination conditions in a room, and the degree of improvement when using an ICC-profile, the results from the measurements was processed and analyzed. Eye-One Beamer from GretagMacbeth was used to make the profiles. The color image quality was evaluated both visually and by color difference calculations. The results from the analysis indicated large visual and colorimetric differences between the projectors. Our DLP projectors have generally smaller color gamut than LCD projectors. The color gamuts of older projectors are significantly smaller than that of newer ones. The amount of ambient light reaching the screen is of great importance for the visual impression. If too much reflections and other ambient light reaches the screen, the projected image gets pale and has low contrast. When using a profile, the differences in colors between the projectors gets smaller and the colors appears more correct. For one device, the average ΔE*ab color difference when compared to a relative white reference was reduced from 22 to 11, for another from 13 to 6. Blue colors have the largest variations among the projection displays and makes them

  13. Color image quality in projection displays: a case study

    NASA Astrophysics Data System (ADS)

    Strand, Monica; Hardeberg, Jon Y.; Nussbaum, Peter

    2004-10-01

    Recently the use of projection displays has increased dramatically in different applications such as digital cinema, home theatre, and business and educational presentations. Even if the color image quality of these devices has improved significantly over the years, it is still a common situation for users of projection displays that the projected colors differ significantly from the intended ones. This study presented in this paper attempts to analyze the color image quality of a large set of projection display devices, particularly investigating the variations in color reproduction. As a case study, a set of 14 projectors (LCD and DLP technology) at Gjøvik University College have been tested under four different conditions: dark and light room, with and without using an ICC-profile. To find out more about the importance of the illumination conditions in a room, and the degree of improvement when using an ICC-profile, the results from the measurements was processed and analyzed. Eye-One Beamer from GretagMacbeth was used to make the profiles. The color image quality was evaluated both visually and by color difference calculations. The results from the analysis indicated large visual and colorimetric differences between the projectors. Our DLP projectors have generally smaller color gamut than LCD projectors. The color gamuts of older projectors are significantly smaller than that of newer ones. The amount of ambient light reaching the screen is of great importance for the visual impression. If too much reflections and other ambient light reaches the screen, the projected image gets pale and has low contrast. When using a profile, the differences in colors between the projectors gets smaller and the colors appears more correct. For one device, the average ΔE*ab color difference when compared to a relative white reference was reduced from 22 to 11, for another from 13 to 6. Blue colors have the largest variations among the projection displays and makes them

  14. Image Quality of the Helioseismic and Magnetic Imager (HMI) Onboard the Solar Dynamics Observatory (SDO)

    NASA Technical Reports Server (NTRS)

    Wachter, R.; Schou, Jesper; Rabello-Soares, M. C.; Miles, J. W.; Duvall, T. L., Jr.; Bush, R. I.

    2011-01-01

    We describe the imaging quality of the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) as measured during the ground calibration of the instrument. We describe the calibration techniques and report our results for the final configuration of HMI. We present the distortion, modulation transfer function, stray light,image shifts introduced by moving parts of the instrument, best focus, field curvature, and the relative alignment of the two cameras. We investigate the gain and linearity of the cameras, and present the measured flat field.

  15. Comparison of image quality in computed laminography and tomography.

    PubMed

    Xu, Feng; Helfen, Lukas; Baumbach, Tilo; Suhonen, Heikki

    2012-01-16

    In computed tomography (CT), projection images of the sample are acquired over an angular range between 180 to 360 degrees around a rotation axis. A special case of CT is that of limited-angle CT, where some of the rotation angles are inaccessible, leading to artefacts in the reconstrucion because of missing information. The case of flat samples is considered, where the projection angles that are close to the sample surface are either i) completely unavailable or ii) very noisy due to the limited transmission at these angles. Computed laminography (CL) is an imaging technique especially suited for flat samples. CL is a generalization of CT that uses a rotation axis tilted by less than 90 degrees with respect to the incident beam. Thus CL avoids using projections from angles closest to the sample surface. We make a quantitative comparison of the imaging artefacts between CL and limited-angle CT for the case of a parallel-beam geometry. Both experimental and simulated images are used to characterize the effect of the artefacts on the resolution and visible image features. The results indicate that CL has an advantage over CT in cases when the missing angular range is a significant portion of the total angular range. In the case when the quality of the projections is limited by noise, CT allows a better tradeoff between the noise level and the missing angular range. PMID:22274425

  16. Integrating satellite images and spectroscopy to measuring green and black tea quality.

    PubMed

    Dutta, R; Stein, A; Bhagat, R M

    2011-07-15

    This study quantifies the effects of green leaf and black tea parameters that influence tea quality in Northeast India. It was motivated by a decline in tea quality that is of concern to tea growers. The rationale of the study is to identify the different parameters that have a significant influence on liquor brightness and other variables measuring tea quality. Here, we investigate several methods for estimating tea quality based on tea quality data, near infrared spectroscopy and remotely sensed data (NDVI). Attention focused on two high yielding clones (TV1 and S3A3). NDVI was obtained from ASTER images. Statistical analysis shows that liquor brightness is affected by the levels of caffeine content, theaflavins and catechins. Relationships exist between quality parameters and remote sensing in particular for the S3A3 clone. NDVI has a positive relation with caffeine, theogallin, EC, and ECG. NIR is negatively related to caffeine, theogallin, and catechins. We conclude that NDVI and Near Infrared (NIR) spectroscopy have a large potential to be used for monitoring tea quality in the future. PMID:23140747

  17. Patient dose and image quality from mega-voltage cone beam computed tomography imaging

    SciTech Connect

    Gayou, Olivier; Parda, David S.; Johnson, Mark; Miften, Moyed

    2007-02-15

    The evolution of ever more conformal radiation delivery techniques makes the subject of accurate localization of increasing importance in radiotherapy. Several systems can be utilized including kilo-voltage and mega-voltage cone-beam computed tomography (MV-CBCT), CT on rail or helical tomography. One of the attractive aspects of mega-voltage cone-beam CT is that it uses the therapy beam along with an electronic portal imaging device to image the patient prior to the delivery of treatment. However, the use of a photon beam energy in the mega-voltage range for volumetric imaging degrades the image quality and increases the patient radiation dose. To optimize image quality and patient dose in MV-CBCT imaging procedures, a series of dose measurements in cylindrical and anthropomorphic phantoms using an ionization chamber, radiographic films, and thermoluminescent dosimeters was performed. Furthermore, the dependence of the contrast to noise ratio and spatial resolution of the image upon the dose delivered for a 20-cm-diam cylindrical phantom was evaluated. Depending on the anatomical site and patient thickness, we found that the minimum dose deposited in the irradiated volume was 5-9 cGy and the maximum dose was between 9 and 17 cGy for our clinical MV-CBCT imaging protocols. Results also demonstrated that for high contrast areas such as bony anatomy, low doses are sufficient for image registration and visualization of the three-dimensional boundaries between soft tissue and bony structures. However, as the difference in tissue density decreased, the dose required to identify soft tissue boundaries increased. Finally, the dose delivered by MV-CBCT was simulated using a treatment planning system (TPS), thereby allowing the incorporation of MV-CBCT dose in the treatment planning process. The TPS-calculated doses agreed well with measurements for a wide range of imaging protocols.

  18. Effect of nonlinear three-dimensional optimized reconstruction algorithm filter on image quality and radiation dose: Validation on phantoms

    SciTech Connect

    Bai Mei; Chen Jiuhong; Raupach, Rainer; Suess, Christoph; Tao Ying; Peng Mingchen

    2009-01-15

    A new technique called the nonlinear three-dimensional optimized reconstruction algorithm filter (3D ORA filter) is currently used to improve CT image quality and reduce radiation dose. This technical note describes the comparison of image noise, slice sensitivity profile (SSP), contrast-to-noise ratio, and modulation transfer function (MTF) on phantom images processed with and without the 3D ORA filter, and the effect of the 3D ORA filter on CT images at a reduced dose. For CT head scans the noise reduction was up to 54% with typical bone reconstruction algorithms (H70) and a 0.6 mm slice thickness; for liver CT scans the noise reduction was up to 30% with typical high-resolution reconstruction algorithms (B70) and a 0.6 mm slice thickness. MTF and SSP did not change significantly with the application of 3D ORA filtering (P>0.05), whereas noise was reduced (P<0.05). The low contrast detectability and MTF of images obtained at a reduced dose and filtered by the 3D ORA were equivalent to those of standard dose CT images; there was no significant difference in image noise of scans taken at a reduced dose, filtered using 3D ORA and standard dose CT (P>0.05). The 3D ORA filter shows good potential for reducing image noise without affecting image quality attributes such as sharpness. By applying this approach, the same image quality can be achieved whilst gaining a marked dose reduction.

  19. Decision theory applied to image quality control in radiology

    PubMed Central

    Lessa, Patrícia S; Caous, Cristofer A; Arantes, Paula R; Amaro, Edson; de Souza, Fernando M Campello

    2008-01-01

    Background The present work aims at the application of the decision theory to radiological image quality control (QC) in diagnostic routine. The main problem addressed in the framework of decision theory is to accept or reject a film lot of a radiology service. The probability of each decision of a determined set of variables was obtained from the selected films. Methods Based on a radiology service routine a decision probability function was determined for each considered group of combination characteristics. These characteristics were related to the film quality control. These parameters were also framed in a set of 8 possibilities, resulting in 256 possible decision rules. In order to determine a general utility application function to access the decision risk, we have used a simple unique parameter called r. The payoffs chosen were: diagnostic's result (correct/incorrect), cost (high/low), and patient satisfaction (yes/no) resulting in eight possible combinations. Results Depending on the value of r, more or less risk will occur related to the decision-making. The utility function was evaluated in order to determine the probability of a decision. The decision was made with patients or administrators' opinions from a radiology service center. Conclusion The model is a formal quantitative approach to make a decision related to the medical imaging quality, providing an instrument to discriminate what is really necessary to accept or reject a film or a film lot. The method presented herein can help to access the risk level of an incorrect radiological diagnosis decision. PMID:19014545

  20. Image quality evaluation of breast tomosynthesis with synchrotron radiation

    SciTech Connect

    Malliori, A.; Bliznakova, K.; Speller, R. D.; Horrocks, J. A.; Rigon, L.; Tromba, G.; Pallikarakis, N.

    2012-09-15

    Purpose: This study investigates the image quality of tomosynthesis slices obtained from several acquisition sets with synchrotron radiation using a breast phantom incorporating details that mimic various breast lesions, in a heterogeneous background. Methods: A complex Breast phantom (MAMMAX) with a heterogeneous background and thickness that corresponds to 4.5 cm compressed breast with an average composition of 50% adipose and 50% glandular tissue was assembled using two commercial phantoms. Projection images using acquisition arcs of 24 Degree-Sign , 32 Degree-Sign , 40 Degree-Sign , 48 Degree-Sign , and 56 Degree-Sign at incident energy of 17 keV were obtained from the phantom with the synchrotron radiation for medical physics beamline at ELETTRA Synchrotron Light Laboratory. The total mean glandular dose was set equal to 2.5 mGy. Tomograms were reconstructed with simple multiple projection algorithm (MPA) and filtered MPA. In the latter case, a median filter, a sinc filter, and a combination of those two filters were applied on the experimental data prior to MPA reconstruction. Visual inspection, contrast to noise ratio, contrast, and artifact spread function were the figures of merit used in the evaluation of the visualisation and detection of low- and high-contrast breast features, as a function of the reconstruction algorithm and acquisition arc. To study the benefits of using monochromatic beams, single projection images at incident energies ranging from 14 to 27 keV were acquired with the same phantom and weighted to synthesize polychromatic images at a typical incident x-ray spectrum with W target. Results: Filters were optimised to reconstruct features with different attenuation characteristics and dimensions. In the case of 6 mm low-contrast details, improved visual appearance as well as higher contrast to noise ratio and contrast values were observed for the two filtered MPA algorithms that exploit the sinc filter. These features are better visualized

  1. Taking image quality factor into the OPC model tuning flow

    NASA Astrophysics Data System (ADS)

    Wang, Ching-Heng; Liu, Qingwei; Zhang, Liguo

    2007-03-01

    All OPC model builders are in search of a physically realistic model that is adequately calibrated and contains the information that can be used for process predictions and analysis of a given process. But there still are some unknown physics in the process and wafer data sets are not perfect. Most cases even using the average values of different empirical data sets will still take inaccurate measurements into the model fitting process, which makes the fitting process more time consuming and also may cause losing convergence and stability. The Image quality is one of the most worrisome obstacles faced by next-generation lithography. Nowadays, considerable effort is devoted to enhance the contrast, as well as understanding its impact on devices. It is a persistent problem for 193nm micro-lithography and will carry us for at least three generations, culminating with immersion lithography. This work is to weight different wafer data points with a weighting function. The weighting function is dependent on the Normal image log slope (NILS), which can reflect the image quality. Using this approach, we can filter wrong information of the process and make the OPC model more accurate. CalibreWorkbench is the platform we used in this study, which has been proven to have an excellent performance on 0.13um, 90nm and 65nm production and development models setup. Leveraging its automatic optical-tuning function, we practiced the best weighting approach to achieve the most efficient and convergent tuning flow.

  2. Perceptual quality metric of color quantization errors on still images

    NASA Astrophysics Data System (ADS)

    Pefferkorn, Stephane; Blin, Jean-Louis

    1998-07-01

    A new metric for the assessment of color image coding quality is presented in this paper. Two models of chromatic and achromatic error visibility have been investigated, incorporating many aspects of human vision and color perception. The achromatic model accounts for both retinal and cortical phenomena such as visual sensitivity to spatial contrast and orientation. The chromatic metric is based on a multi-channel model of human color vision that is parameterized for video coding applications using psychophysical experiments, assuming that perception of color quantization errors can be assimilated to perception of supra-threshold local color-differences. The final metric is a merging of the chromatic model and the achromatic model which accounts for phenomenon as masking. The metric is tested on 6 real images at 5 quality levels using subjective assessments. The high correlation between objective and subjective scores shows that the described metric accurately rates the rendition of important features of the image such as color contours and textures.

  3. A hyperspectral imaging prototype for online quality evaluation of pickling cucumbers

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A hyperspectral imaging prototype was developed for online evaluation of external and internal quality of pickling cucumbers. The prototype had several new, unique features including simultaneous reflectance and transmittance imaging and inline, real time calibration of hyperspectral images of each ...

  4. Image quality: An overview; Proceedings of the Meeting, Arlington, VA, April 9, 10, 1985

    NASA Astrophysics Data System (ADS)

    Granger, E. M.; Baker, L. R.

    1985-12-01

    Various papers on image quality are presented. The subjects discussed include: image quality considerations in transform coding, psychophysical approach to image quality, a decision theory approach to tone reproduction, Fourier analysis of image raggedness, lens performance assessment by image quality criteria, results of preliminary work on objective MRTD measurement, resolution requirements for binarization of line art, and problems of the visual display in flight simulation. Also addressed are: emittance in thermal imaging applications, optical performance requirements for thermal imaging lenses, dynamic motion measurement using digital TV speckle interferometry, quality assurance for borescopes, versatile projector test device, operational MTF for Landsat Thematic Mapper, operational use of color perception to enhance satellite image quality, theoretical bases and measurement of the MTF of integrated image sensors, measurement of the MTF of thermal and other video systems, and underflight calibration of the Landsat Thematic Mapper.

  5. Vertical or horizontal orientation of foot radiographs does not affect image interpretation

    PubMed Central

    Ferran, Nicholas Antonio; Ball, Luke; Maffulli, Nicola

    2012-01-01

    Summary This study determined whether the orientation of dorsoplantar and oblique foot radiographs has an effect on radiograph interpretation. A test set of 50 consecutive foot radiographs were selected (25 with fractures, and 25 normal), and duplicated in the horizontal orientation. The images were randomly arranged, numbered 1 through 100, and analysed by six image interpreters. Vertical and horizontal area under the ROC curve, accuracy, sensitivity and specificity were calculated for each image interpreter. There was no significant difference in the area under the ROC curve, accuracy, sensitivity or specificity of image interpretation between images viewed in the vertical or horizontal orientation. While conventions for display of radiographs may help to improve the development of an efficient visual search strategy in trainees, and allow for standardisation of publication of radiographic images, variation from the convention in clinical practice does not appear to affect the sensitivity or specificity of image interpretation. PMID:23738310

  6. Change in Image Quality According to the 3D Locations of a CBCT Phantom.

    PubMed

    Hwang, Jae Joon; Park, Hyok; Jeong, Ho-Gul; Han, Sang-Sun

    2016-01-01

    A patient's position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV). To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan) and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea) were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR), 70.49% (homogeneity), and 13.64% (MTF10%). Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object's position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important. PMID:27093639

  7. Change in Image Quality According to the 3D Locations of a CBCT Phantom

    PubMed Central

    Hwang, Jae Joon; Park, Hyok; Jeong, Ho-Gul; Han, Sang-Sun

    2016-01-01

    A patient’s position changes in every CBCT scan despite patient alignment protocols. However, there have been studies to determine image quality differences when an object is located at the center of the field of view (FOV). To evaluate changes in the image quality of the CBCT scan according to different object positions, the image quality indexes of the Alphard 3030 (Alphard Roentgen Ind., Ltd., Kyoto, Japan) and the Rayscan Symphony (RAY Ind., Ltd., Suwon, Korea) were measured using the Quart DVT_AP phantom at the center of the FOV and 6 peripheral positions under four types of exposure conditions. Anterior, posterior, right, left, upper, and lower positions 1 cm offset from the center of the FOV were used for the peripheral positions. We evaluated and compared the voxel size, homogeneity, contrast to noise ratio (CNR), and the 10% point of the modulation transfer function (MTF10%) of the center and periphery. Because the voxel size, which is determined by the Nyquist frequency, was within tolerance, other image quality indexes were not influenced by the voxel size. For the CNR, homogeneity, and MTF10%, there were peripheral positions which showed considerable differences with statistical significance. The average difference between the center and periphery was up to 31.27% (CNR), 70.49% (homogeneity), and 13.64% (MTF10%). Homogeneity was under tolerance at some of the peripheral locations. Because the CNR, homogeneity, and MTF10% were significantly affected by positional changes of the phantom, an object’s position can influence the interpretation of follow up CBCT images. Therefore, efforts to locate the object in the same position are important. PMID:27093639

  8. Functional magnetic resonance imaging of awake monkeys: some approaches for improving imaging quality

    PubMed Central

    Chen, Gang; Wang, Feng; Dillenburger, Barbara C.; Friedman, Robert M.; Chen, Li M.; Gore, John C.; Avison, Malcolm J.; Roe, Anna W.

    2011-01-01

    Functional magnetic resonance imaging (fMRI), at high magnetic field strength can suffer from serious degradation of image quality because of motion and physiological noise, as well as spatial distortions and signal losses due to susceptibility effects. Overcoming such limitations is essential for sensitive detection and reliable interpretation of fMRI data. These issues are particularly problematic in studies of awake animals. As part of our initial efforts to study functional brain activations in awake, behaving monkeys using fMRI at 4.7T, we have developed acquisition and analysis procedures to improve image quality with encouraging results. We evaluated the influence of two main variables on image quality. First, we show how important the level of behavioral training is for obtaining good data stability and high temporal signal-to-noise ratios. In initial sessions, our typical scan session lasted 1.5 hours, partitioned into short (<10 minutes) runs. During reward periods and breaks between runs, the monkey exhibited movements resulting in considerable image misregistrations. After a few months of extensive behavioral training, we were able to increase the length of individual runs and the total length of each session. The monkey learned to wait until the end of a block for fluid reward, resulting in longer periods of continuous acquisition. Each additional 60 training sessions extended the duration of each session by 60 minutes, culminating, after about 140 training sessions, in sessions that last about four hours. As a result, the average translational movement decreased from over 500 μm to less than 80 μm, a displacement close to that observed in anesthetized monkeys scanned in a 7 T horizontal scanner. Another major source of distortion at high fields arises from susceptibility variations. To reduce such artifacts, we used segmented gradient-echo echo-planar imaging (EPI) sequences. Increasing the number of segments significantly decreased susceptibility

  9. Image quality in CT: From physical measurements to model observers.

    PubMed

    Verdun, F R; Racine, D; Ott, J G; Tapiovaara, M J; Toroi, P; Bochud, F O; Veldkamp, W J H; Schegerer, A; Bouwman, R W; Giron, I Hernandez; Marshall, N W; Edyvean, S

    2015-12-01

    Evaluation of image quality (IQ) in Computed Tomography (CT) is important to ensure that diagnostic questions are correctly answered, whilst keeping radiation dose to the patient as low as is reasonably possible. The assessment of individual aspects of IQ is already a key component of routine quality control of medical x-ray devices. These values together with standard dose indicators can be used to give rise to 'figures of merit' (FOM) to characterise the dose efficiency of the CT scanners operating in certain modes. The demand for clinically relevant IQ characterisation has naturally increased with the development of CT technology (detectors efficiency, image reconstruction and processing), resulting in the adaptation and evolution of assessment methods. The purpose of this review is to present the spectrum of various methods that have been used to characterise image quality in CT: from objective measurements of physical parameters to clinically task-based approaches (i.e. model observer (MO) approach) including pure human observer approach. When combined together with a dose indicator, a generalised dose efficiency index can be explored in a framework of system and patient dose optimisation. We will focus on the IQ methodologies that are required for dealing with standard reconstruction, but also for iterative reconstruction algorithms. With this concept the previously used FOM will be presented with a proposal to update them in order to make them relevant and up to date with technological progress. The MO that objectively assesses IQ for clinically relevant tasks represents the most promising method in terms of radiologist sensitivity performance and therefore of most relevance in the clinical environment. PMID:26459319

  10. Dental caries affects body weight, growth and quality of life in pre-school children.

    PubMed

    Sheiham, A

    2006-11-25

    The effect of a relatively common chronic disease, severe dental caries, affects young childrens' growth and well-being. Treating dental caries in pre-school children would increase growth rates and the quality of life of millions of children. Severe untreated dental caries is common in pre-school children in many countries. Children with severe caries weighed less than controls, and after treatment of decayed teeth there was more rapid weight gain and improvements in their quality of life. This may be due to dietary intake improving because pain affected the quantity and variety of food eaten, and second, chronic inflammation from caries related pulpitis and abscesses is known to suppress growth through a metabolic pathway and to reduce haemoglobin as a result of depressed erythrocyte production. PMID:17128231

  11. Degraded visual environment image/video quality metrics

    NASA Astrophysics Data System (ADS)

    Baumgartner, Dustin D.; Brown, Jeremy B.; Jacobs, Eddie L.; Schachter, Bruce J.

    2014-06-01

    A number of image quality metrics (IQMs) and video quality metrics (VQMs) have been proposed in the literature for evaluating techniques and systems for mitigating degraded visual environments. Some require both pristine and corrupted imagery. Others require patterned target boards in the scene. None of these metrics relates well to the task of landing a helicopter in conditions such as a brownout dust cloud. We have developed and used a variety of IQMs and VQMs related to the pilot's ability to detect hazards in the scene and to maintain situational awareness. Some of these metrics can be made agnostic to sensor type. Not only are the metrics suitable for evaluating algorithm and sensor variation, they are also suitable for choosing the most cost effective solution to improve operating conditions in degraded visual environments.

  12. Perceptual image quality assessment: recent progress and trends

    NASA Astrophysics Data System (ADS)

    Lin, Weisi; Narwaria, Manish

    2010-07-01

    Image quality assessment (IQA) is useful in many visual processing systems but challenging to perform in line with the human perception. A great deal of recent research effort has been directed towards IQA. In order to overcome the difficulty and infeasibility of subjective tests in many situations, the aim of such effort is to assess visual quality objectively towards better alignment with the perception of the Human Visual system (HVS). In this work, we review and analyze the recent progress in the areas related to IQA, as well as giving our views whenever possible. Following the recent trends, we discuss the engineering approach in more details, explore the related aspects for feature pooling, and present a case study with machine learning.

  13. Image quality of a cone beam O-arm 3D imaging system

    NASA Astrophysics Data System (ADS)

    Zhang, Jie; Weir, Victor; Lin, Jingying; Hsiung, Hsiang; Ritenour, E. Russell

    2009-02-01

    The O-arm is a cone beam imaging system designed primarily to support orthopedic surgery and is also used for image-guided and vascular surgery. Using a gantry that can be opened or closed, the O-arm can function as a 2-dimensional (2D) fluoroscopy device or collect 3-dimensional (3D) volumetric imaging data like a CT system. Clinical applications of the O-arm in spine surgical procedures, assessment of pedicle screw position, and kyphoplasty procedures show that the O-arm 3D mode provides enhanced imaging information compared to radiographs or fluoroscopy alone. In this study, the image quality of an O-arm system was quantitatively evaluated. A 20 cm diameter CATPHAN 424 phantom was scanned using the pre-programmed head protocols: small/medium (120 kVp, 100 mAs), large (120 kVp, 128 mAs), and extra-large (120 kVp, 160 mAs) in 3D mode. High resolution reconstruction mode (512×512×0.83 mm) was used to reconstruct images for the analysis of low and high contrast resolution, and noise power spectrum. MTF was measured using the point spread function. The results show that the O-arm image is uniform but with a noise pattern which cannot be removed by simply increasing the mAs. The high contrast resolution of the O-arm system was approximately 9 lp/cm. The system has a 10% MTF at 0.45 mm. The low-contrast resolution cannot be decided due to the noise pattern. For surgery where locations of a structure are emphasized over a survey of all image details, the image quality of the O-arm is well accepted clinically.

  14. Automated techniques for quality assurance of radiological image modalities

    NASA Astrophysics Data System (ADS)

    Goodenough, David J.; Atkins, Frank B.; Dyer, Stephen M.

    1991-05-01

    This paper will attempt to identify many of the important issues for quality assurance (QA) of radiological modalities. It is of course to be realized that QA can span many aspects of the diagnostic decision making process. These issues range from physical image performance levels to and through the diagnostic decision of the radiologist. We will use as a model for automated approaches a program we have developed to work with computed tomography (CT) images. In an attempt to unburden the user, and in an effort to facilitate the performance of QA, we have been studying automated approaches. The ultimate utility of the system is its ability to render in a safe and efficacious manner, decisions that are accurate, sensitive, specific and which are possible within the economic constraints of modern health care delivery.

  15. Sentinel-2 geometric image quality commissioning: first results

    NASA Astrophysics Data System (ADS)

    Languille, F.; Déchoz, C.; Gaudel, A.; Greslou, D.; de Lussy, F.; Trémas, T.; Poulain, V.

    2015-10-01

    In the frame of the Copernicus program of the European Comission, Sentinel-2 will offer multispectral highspatial- resolution optical images over global terrestrial surfaces. In cooperation with ESA, the Centre National d'Etudes Spatiales (CNES) is in charge of the image quality of the project, and will so ensure the CAL/VAL commissioning phase during the months following the launch. Sentinel-2 is a constellation of 2 satellites on a polar sun-synchronous orbit with a revisit time of 5 days (with both satellites), a high field of view - 290km, 13 spectral bands in visible and shortwave infrared, and high spatial resolution - 10m, 20m and 60m. The Sentinel-2 mission offers a global coverage over terrestrial surfaces. The satellites acquire systematically terrestrial surfaces under the same viewing conditions in order to have temporal images stacks. The first satellite has been launched in June 2015. Following the launch, the CAL/VAL commissioning phase will then last during 6 months for geometrical calibration. This paper first provides explanations about Sentinel-2 products delivered with geometric corrections. Then this paper details calibration sites, and the methods used for geometrical parameters calibration and presents the first linked results. The following topics are presented: viewing frames orientation assessment, focal plane mapping for all spectral bands, first results on geolocation assessment, and multispectral registration. There is a systematic images recalibration over a same reference which will be a set of S2 images produced during the 6 months of CAL/VAL. As it takes time to have all needed images, the geolocation performance with ground control points and the multitemporal performance are only first results and will be improved during the last phase of the CAL/VAL. So this paper mainly shows the system performances, the preliminary product performances and the way to perform them.

  16. Evaluation of variations and affecting factors of eco-environmental quality during urbanization.

    PubMed

    Cui, Erqian; Ren, Lijun; Sun, Haoyu

    2015-03-01

    Regional eco-environmental quality is the foundation of economic sustainable development and rational utilization of resources. It is necessary to understand and evaluate the regional eco-environmental quality correctly. Based on national remote sensing land use data, normalized difference vegetation index (NDVI) data and some other statistical data, this paper established an eco-environmental quality index (EQI) model to evaluate the ecological status of Jinan from 2000 to 2011. The results of eco-environmental quality showed little variation, with EQI values ranged from 62.00 to 69.01. EQI of each region in Jinan firstly decreased sharply and then increased slowly with the development of local economy. Besides the spatial and temporal variations analysis, affecting factors of eco-environmental quality was also discussed in this article. According to the results of correlation and regression analysis, meteorological conditions (rainfall and sunshine duration) and industrial structure (the proportion of primary industry) had relatively high correlations with eco-environmental quality. To summarize, a better eco-environmental status is associated with increasing rainfall, shorter sunshine duration, and lower proportion of primary industry. This article aims to giving supporting data and decision-making bases to restore the ecological environment and promote the sustainable development of Jinan. PMID:25369921

  17. SAR image quality effects of damped phase and amplitude errors

    NASA Astrophysics Data System (ADS)

    Zelenka, Jerry S.; Falk, Thomas

    The effects of damped multiplicative, amplitude, or phase errors on the image quality of synthetic-aperture radar systems are considered. These types of errors can result from aircraft maneuvers or the mechanical steering of an antenna. The proper treatment of damped multiplicative errors can lead to related design specifications and possibly an enhanced collection capability. Only small, high-frequency errors are considered. Expressions for the average intensity and energy associated with a damped multiplicative error are presented and used to derive graphic results. A typical example is used to show how to apply the results of this effort.

  18. An automated system for numerically rating document image quality

    SciTech Connect

    Cannon, M.; Kelly, P.; Iyengar, S.S.; Brener, N.

    1997-04-01

    As part of the Department of Energy document declassification program, the authors have developed a numerical rating system to predict the OCR error rate that they expect to encounter when processing a particular document. The rating algorithm produces a vector containing scores for different document image attributes such as speckle and touching characters. The OCR error rate for a document is computed from a weighted sum of the elements of the corresponding quality vector. The predicted OCR error rate will be used to screen documents that would not be handled properly with existing document processing products.

  19. New strategy for image and video quality assessment

    NASA Astrophysics Data System (ADS)

    Ma, Qi; Zhang, Liming; Wang, Bin

    2010-01-01

    Image and video quality assessment (QA) is a critical issue in image and video processing applications. General full-reference (FR) QA criteria such as peak signal-to-noise ratio (PSNR) and mean squared error (MSE) do not accord well with human subjective assessment. Some QA indices that consider human visual sensitivity, such as mean structural similarity (MSSIM) with structural sensitivity, visual information fidelity (VIF) with statistical sensitivity, etc., were proposed in view of the differences between reference and distortion frames on a pixel or local level. However, they ignore the role of human visual attention (HVA). Recently, some new strategies with HVA have been proposed, but the methods extracting the visual attention are too complex for real-time realization. We take advantage of the phase spectrum of quaternion Fourier transform (PQFT), a very fast algorithm we previously proposed, to extract saliency maps of color images or videos. Then we propose saliency-based methods for both image QA (IQA) and video QA (VQA) by adding weights related to saliency features to these original IQA or VQA criteria. Experimental results show that our saliency-based strategy can approach more closely to human subjective assessment compared with these original IQA or VQA methods and does not take more time because of the fast PQFT algorithm.

  20. Improve the image quality of orbital 3 T diffusion-weighted magnetic resonance imaging with readout-segmented echo-planar imaging.

    PubMed

    Xu, Xiao-Quan; Liu, Jun; Hu, Hao; Su, Guo-Yi; Zhang, Yu-Dong; Shi, Hai-Bin; Wu, Fei-Yun

    2016-01-01

    The aim of our study is to compare the image quality of readout-segmented echo-planar imaging (rs-EPI) and that of standard single-shot EPI (ss-EPI) in orbital 3 T diffusion-weighted (DW) magnetic resonance (MR) imaging in healthy subjects. Forty-two volunteers underwent two sets of orbital DW imaging scan at a 3 T MR unit, and image quality was assessed qualitatively and quantitatively. As a result, we found that rs-EPI could provide better image quality than standard ss-EPI, while no significant difference was found on the apparent diffusion coefficient between the two sets of DW images. PMID:27317226

  1. Trauma-related symptoms in neglected preschoolers and affective quality of mother-child communication.

    PubMed

    Milot, Tristan; St-Laurent, Diane; Ethier, Louise S; Provost, Marc A

    2010-11-01

    This study (a) assessed whether child neglect is associated with posttraumatic stress disorder (PTSD) and dissociative symptoms in the preschool period and (b) examined the role of quality of mother-child affective communication in the development of trauma-related symptoms among neglected children. Participants were 33 neglected and 72 non-neglected preschoolers (mean age = 60 months). Neglected children were recruited from the Child Protection Agencies. Neglected and non-neglected children victims of other form of abuse were excluded from the study. Trauma symptoms were evaluated through mother and preschool teacher reports. Quality of mother-child affective communication was assessed in a lab visit during an unstructured task. According to teachers, neglected children displayed more PTSD and dissociative symptoms than non-neglected children. Quality of mother-child communication was lower in neglected dyads. Mother-child affective communication predicted teacher-reported child trauma symptomatology, over and above child neglect. Discussion focuses on the traumatic nature of child neglect and the underlying parent-child relational processes. PMID:20930179

  2. Undetectable Changes in Image Resolution of Luminance-Contrast Gradients Affect Depth Perception

    PubMed Central

    Tsushima, Yoshiaki; Komine, Kazuteru; Sawahata, Yasuhito; Morita, Toshiya

    2016-01-01

    A great number of studies have suggested a variety of ways to get depth information from two dimensional images such as binocular disparity, shape-from-shading, size gradient/foreshortening, aerial perspective, and so on. Are there any other new factors affecting depth perception? A recent psychophysical study has investigated the correlation between image resolution and depth sensation of Cylinder images (A rectangle contains gradual luminance-contrast changes.). It was reported that higher resolution images facilitate depth perception. However, it is still not clear whether or not the finding generalizes to other kinds of visual stimuli, because there are more appropriate visual stimuli for exploration of depth perception of luminance-contrast changes, such as Gabor patch. Here, we further examined the relationship between image resolution and depth perception by conducting a series of psychophysical experiments with not only Cylinders but also Gabor patches having smoother luminance-contrast gradients. As a result, higher resolution images produced stronger depth sensation with both images. This finding suggests that image resolution affects depth perception of simple luminance-contrast differences (Gabor patch) as well as shape-from-shading (Cylinder). In addition, this phenomenon was found even when the resolution difference was undetectable. This indicates the existence of consciously available and unavailable information in our visual system. These findings further support the view that image resolution is a cue for depth perception that was previously ignored. It partially explains the unparalleled viewing experience of novel high resolution displays. PMID:26941693

  3. Retinal Image Quality Assessment for Spaceflight-Induced Vision Impairment Study

    NASA Technical Reports Server (NTRS)

    Vu, Amanda Cadao; Raghunandan, Sneha; Vyas, Ruchi; Radhakrishnan, Krishnan; Taibbi, Giovanni; Vizzeri, Gianmarco; Grant, Maria; Chalam, Kakarla; Parsons-Wingerter, Patricia

    2015-01-01

    Long-term exposure to space microgravity poses significant risks for visual impairment. Evidence suggests such vision changes are linked to cephalad fluid shifts, prompting a need to directly quantify microgravity-induced retinal vascular changes. The quality of retinal images used for such vascular remodeling analysis, however, is dependent on imaging methodology. For our exploratory study, we hypothesized that retinal images captured using fluorescein imaging methodologies would be of higher quality in comparison to images captured without fluorescein. A semi-automated image quality assessment was developed using Vessel Generation Analysis (VESGEN) software and MATLAB® image analysis toolboxes. An analysis of ten images found that the fluorescein imaging modality provided a 36% increase in overall image quality (two-tailed p=0.089) in comparison to nonfluorescein imaging techniques.

  4. A color image quality assessment using a reduced-reference image machine learning expert

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Lebrun, Gilles; Lezoray, Olivier

    2008-01-01

    A quality metric based on a classification process is introduced. The main idea of the proposed method is to avoid the error pooling step of many factors (in frequential and spatial domain) commonly applied to obtain a final quality score. A classification process based on final quality class with respect to the standard quality scale provided by the UIT. Thus, for each degraded color image, a feature vector is computed including several Human Visual System characteristics, such as, contrast masking effect, color correlation, and so on. Selected features are of two kinds: 1) full-reference features and 2) no-reference characteristics. That way, a machine learning expert, providing a final class number is designed.

  5. A novel technique of image quality objective measurement by wavelet analysis throughout the spatial frequency range

    NASA Astrophysics Data System (ADS)

    Luo, Gaoyong

    2005-01-01

    An essential determinant of the value of surrogate digital images is their quality. Image quality measurement has become crucial for most image processing applications. Over the past years , there have been many attempts to develop models or metrics for image quality that incorporate elements of human visual sensitivity. However, there is no current standard and objective definition of spectral image quality. This paper proposes a reliable automatic method for objective image quality measurement by wavelet analysis throughout the spatial frequency range. This is done by a detailed analysis of an image for a wide range of spatial frequency content, using a combination of modulation transfer function (MTF), brightness, contrast, saturation, sharpness and noise, as a more revealing metric for quality evaluation. A fast lifting wavelet algorithm is developed for computationally efficient spatial frequency analysis, where fine image detail corresponding to high spatial frequencies and image sharpness in regard to lower and mid -range spatial frequencies can be examined and compared accordingly. The wavelet frequency deconstruction is actually to extract the feature of edges in sub-band images. The technique provides a means to relate the quality of an image to the interpretation and quantification throughout the frequency range, in which the noise level is estimated in assisting with quality analysis. The experimental results of using this method for image quality measurement exhibit good correlation to subjective visual quality assessments.

  6. A novel technique of image quality objective measurement by wavelet analysis throughout the spatial frequency range

    NASA Astrophysics Data System (ADS)

    Luo, Gaoyong

    2004-10-01

    An essential determinant of the value of surrogate digital images is their quality. Image quality measurement has become crucial for most image processing applications. Over the past years , there have been many attempts to develop models or metrics for image quality that incorporate elements of human visual sensitivity. However, there is no current standard and objective definition of spectral image quality. This paper proposes a reliable automatic method for objective image quality measurement by wavelet analysis throughout the spatial frequency range. This is done by a detailed analysis of an image for a wide range of spatial frequency content, using a combination of modulation transfer function (MTF), brightness, contrast, saturation, sharpness and noise, as a more revealing metric for quality evaluation. A fast lifting wavelet algorithm is developed for computationally efficient spatial frequency analysis, where fine image detail corresponding to high spatial frequencies and image sharpness in regard to lower and mid -range spatial frequencies can be examined and compared accordingly. The wavelet frequency deconstruction is actually to extract the feature of edges in sub-band images. The technique provides a means to relate the quality of an image to the interpretation and quantification throughout the frequency range, in which the noise level is estimated in assisting with quality analysis. The experimental results of using this method for image quality measurement exhibit good correlation to subjective visual quality assessments.

  7. Measuring saliency in images: which experimental parameters for the assessment of image quality?

    NASA Astrophysics Data System (ADS)

    Fredembach, Clement; Woolfe, Geoff; Wang, Jue

    2012-01-01

    Predicting which areas of an image are perceptually salient or attended to has become an essential pre-requisite of many computer vision applications. Because observers are notoriously unreliable in remembering where they look a posteriori, and because asking where they look while observing the image necessarily in uences the results, ground truth about saliency and visual attention has to be obtained by gaze tracking methods. From the early work of Buswell and Yarbus to the most recent forays in computer vision there has been, perhaps unfortunately, little agreement on standardisation of eye tracking protocols for measuring visual attention. As the number of parameters involved in experimental methodology can be large, their individual in uence on the nal results is not well understood. Consequently, the performance of saliency algorithms, when assessed by correlation techniques, varies greatly across the literature. In this paper, we concern ourselves with the problem of image quality. Specically: where people look when judging images. We show that in this case, the performance gap between existing saliency prediction algorithms and experimental results is signicantly larger than otherwise reported. To understand this discrepancy, we rst devise an experimental protocol that is adapted to the task of measuring image quality. In a second step, we compare our experimental parameters with the ones of existing methods and show that a lot of the variability can directly be ascribed to these dierences in experimental methodology and choice of variables. In particular, the choice of a task, e.g., judging image quality vs. free viewing, has a great impact on measured saliency maps, suggesting that even for a mildly cognitive task, ground truth obtained by free viewing does not adapt well. Careful analysis of the prior art also reveals that systematic bias can occur depending on instrumental calibration and the choice of test images. We conclude this work by proposing a

  8. Hearing the patient's voice? Factors affecting the use of patient survey data in quality improvement

    PubMed Central

    Davies, E; Cleary, P

    2005-01-01

    Objective: To develop a framework for understanding factors affecting the use of patient survey data in quality improvement. Design: Qualitative interviews with senior health professionals and managers and a review of the literature. Setting: A quality improvement collaborative in Minnesota, USA involving teams from eight medical groups, focusing on how to use patient survey data to improve patient centred care. Participants: Eight team leaders (medical, clinical improvement or service quality directors) and six team members (clinical improvement coordinators and managers). Results: Respondents reported three types of barriers before the collaborative: organisational, professional and data related. Organisational barriers included lack of supporting values for patient centred care, competing priorities, and lack of an effective quality improvement infrastructure. Professional barriers included clinicians and staff not being used to focusing on patient interaction as a quality issue, individuals not necessarily having been selected, trained or supported to provide patient centred care, and scepticism, defensiveness or resistance to change following feedback. Data related barriers included lack of expertise with survey data, lack of timely and specific results, uncertainty over the effective interventions or time frames for improvement, and consequent risk of perceived low cost effectiveness of data collection. Factors that appeared to have promoted data use included board led strategies to change culture and create quality improvement forums, leadership from senior physicians and managers, and the persistence of quality improvement staff over several years in demonstrating change in other areas. Conclusion: Using patient survey data may require a more concerted effort than for other clinical data. Organisations may need to develop cultures that support patient centred care, quality improvement capacity, and to align professional receptiveness and leadership with

  9. Image quality degradation and retrieval errors introduced by registration and interpolation of multispectral digital images

    SciTech Connect

    Henderson, B.G.; Borel, C.C.; Theiler, J.P.; Smith, B.W.

    1996-04-01

    Full utilization of multispectral data acquired by whiskbroom and pushbroom imagers requires that the individual channels be registered accurately. Poor registration introduces errors which can be significant, especially in high contrast areas such as boundaries between regions. We simulate the acquisition of multispectral imagery in order to estimate the errors that are introduced by co-registration of different channels and interpolation within the images. We compute the Modulation Transfer Function (MTF) and image quality degradation brought about by fractional pixel shifting and calculate errors in retrieved quantities (surface temperature and water vapor) that occur as a result of interpolation. We also present a method which might be used to estimate sensor platform motion for accurate registration of images acquired by a pushbroom scanner.

  10. Image quality and stability of image-guided radiotherapy (IGRT) devices: A comparative study

    PubMed Central

    Stock, Markus; Pasler, Marlies; Birkfellner, Wolfgang; Homolka, Peter; Poetter, Richard; Georg, Dietmar

    2010-01-01

    Introduction Our aim was to implement standards for quality assurance of IGRT devices used in our department and to compare their performances with that of a CT simulator. Materials and methods We investigated image quality parameters for three devices over a period of 16 months. A multislice CT was used as a benchmark and results related to noise, spatial resolution, low contrast visibility (LCV) and uniformity were compared with a cone beam CT (CBCT) at a linac and simulator. Results All devices performed well in terms of LCV and, in fact, exceeded vendor specifications. MTF was comparable between CT and linac CBCT. Integral nonuniformity was, on average, 0.002 for the CT and 0.006 for the linac CBCT. Uniformity, LCV and MTF varied depending on the protocols used for the linac CBCT. Contrast-to-noise ratio was an average of 51% higher for the CT than for the linac and simulator CBCT. No significant time trend was observed and tolerance limits were implemented. Discussion Reasonable differences in image quality between CT and CBCT were observed. Further research and development are necessary to increase image quality of commercially available CBCT devices in order for them to serve the needs for adaptive and/or online planning. PMID:19695725

  11. Assessment of patient dose and image quality for cardiac CT with breast shields.

    PubMed

    Midgley, S M; Einsiedel, P F; Langenberg, F; Lui, E H; Heinze, S B

    2012-09-01

    Breast shielding can reduce dose to the female breast, a radiosensitive organ receiving significant radiation during computed tomography (CT) chest examinations, particularly in cardiac CT, where Electrocardiogram dose modulation currently precludes the use of radial dose modulation to reduce breast dose. However, breast shields may produce artefacts affecting interpretation of coronary arteries. This study explores the dose savings and the effect of breast shields on image quality with torso and CT dose index body phantoms and an organ dose calculator. Change in dose calculated: 53-63 % (female breast), 82-85 % (lung), 79-84 % (oesophagus) and 76-80 % (effective dose) with larger dose reductions at lower kVp. Image quality is preserved when breast shields are placed after the scout no closer than 10 mm from the skin. Therefore, breast shields can be used in cardiac CT to reduce breast dose without compromising image quality. Revised conversion factors for dose length product to effective dose are suggested for cardiac CT without and with breast shields. PMID:22492837

  12. Relations between local and global perceptual image quality and visual masking

    NASA Astrophysics Data System (ADS)

    Alam, Md Mushfiqul; Patil, Pranita; Hagan, Martin T.; Chandler, Damon M.

    2015-03-01

    Perceptual quality assessment of digital images and videos are important for various image-processing applications. For assessing the image quality, researchers have often used the idea of visual masking (or distortion visibility) to design image-quality predictors specifically for the near-threshold distortions. However, it is still unknown that while assessing the quality of natural images, how the local distortion visibilities relate with the local quality scores. Furthermore, the summing mechanism of the local quality scores to predict the global quality scores is also crucial for better prediction of the perceptual image quality. In this paper, the local and global qualities of six images and six distortion levels were measured using subjective experiments. Gabor-noise target was used as distortion in the quality-assessment experiments to be consistent with our previous study [Alam, Vilankar, Field, and Chandler, Journal of Vision, 2014], in which the local root-mean-square contrast detection thresholds of detecting the Gabor-noise target were measured at each spatial location of the undistorted images. Comparison of the results of this quality-assessment experiment and the previous detection experiment shows that masking predicted the local quality scores more than 95% correctly above 15 dB threshold within 5% subject scores. Furthermore, it was found that an approximate squared summation of local-quality scores predicted the global quality scores suitably (Spearman rank-order correlation 0:97).

  13. Correlation of the clinical and physical image quality in chest radiography for average adults with a computed radiography imaging system

    PubMed Central

    Wood, T J; Beavis, A W; Saunderson, J R

    2013-01-01

    Objective: The purpose of this study was to examine the correlation between the quality of visually graded patient (clinical) chest images and a quantitative assessment of chest phantom (physical) images acquired with a computed radiography (CR) imaging system. Methods: The results of a previously published study, in which four experienced image evaluators graded computer-simulated postero-anterior chest images using a visual grading analysis scoring (VGAS) scheme, were used for the clinical image quality measurement. Contrast-to-noise ratio (CNR) and effective dose efficiency (eDE) were used as physical image quality metrics measured in a uniform chest phantom. Although optimal values of these physical metrics for chest radiography were not derived in this work, their correlation with VGAS in images acquired without an antiscatter grid across the diagnostic range of X-ray tube voltages was determined using Pearson’s correlation coefficient. Results: Clinical and physical image quality metrics increased with decreasing tube voltage. Statistically significant correlations between VGAS and CNR (R=0.87, p<0.033) and eDE (R=0.77, p<0.008) were observed. Conclusion: Medical physics experts may use the physical image quality metrics described here in quality assurance programmes and optimisation studies with a degree of confidence that they reflect the clinical image quality in chest CR images acquired without an antiscatter grid. Advances in knowledge: A statistically significant correlation has been found between the clinical and physical image quality in CR chest imaging. The results support the value of using CNR and eDE in the evaluation of quality in clinical thorax radiography. PMID:23568362

  14. Cone beam computed tomography radiation dose and image quality assessments.

    PubMed

    Lofthag-Hansen, Sara

    2010-01-01

    Diagnostic radiology has undergone profound changes in the last 30 years. New technologies are available to the dental field, cone beam computed tomography (CBCT) as one of the most important. CBCT is a catch-all term for a technology comprising a variety of machines differing in many respects: patient positioning, volume size (FOV), radiation quality, image capturing and reconstruction, image resolution and radiation dose. When new technology is introduced one must make sure that diagnostic accuracy is better or at least as good as the one it can be expected to replace. The CBCT brand tested was two versions of Accuitomo (Morita, Japan): 3D Accuitomo with an image intensifier as detector, FOV 3 cm x 4 cm and 3D Accuitomo FPD with a flat panel detector, FOVs 4 cm x 4 cm and 6 cm x 6 cm. The 3D Accuitomo was compared with intra-oral radiography for endodontic diagnosis in 35 patients with 46 teeth analyzed, of which 41 were endodontically treated. Three observers assessed the images by consensus. The result showed that CBCT imaging was superior with a higher number of teeth diagnosed with periapical lesions (42 vs 32 teeth). When evaluating 3D Accuitomo examinations in the posterior mandible in 30 patients, visibility of marginal bone crest and mandibular canal, important anatomic structures for implant planning, was high with good observer agreement among seven observers. Radiographic techniques have to be evaluated concerning radiation dose, which requires well-defined and easy-to-use methods. Two methods: CT dose index (CTDI), prevailing method for CT units, and dose-area product (DAP) were evaluated for calculating effective dose (E) for both units. An asymmetric dose distribution was revealed when a clinical situation was simulated. Hence, the CTDI method was not applicable for these units with small FOVs. Based on DAP values from 90 patient examinations effective dose was estimated for three diagnostic tasks: implant planning in posterior mandible and

  15. Comprehensive model for predicting perceptual image quality of smart mobile devices.

    PubMed

    Gong, Rui; Xu, Haisong; Luo, M R; Li, Haifeng

    2015-01-01

    An image quality model for smart mobile devices was proposed based on visual assessments of several image quality attributes. A series of psychophysical experiments were carried out on two kinds of smart mobile devices, i.e., smart phones and tablet computers, in which naturalness, colorfulness, brightness, contrast, sharpness, clearness, and overall image quality were visually evaluated under three lighting environments via categorical judgment method for various application types of test images. On the basis of Pearson correlation coefficients and factor analysis, the overall image quality could first be predicted by its two constituent attributes with multiple linear regression functions for different types of images, respectively, and then the mathematical expressions were built to link the constituent image quality attributes with the physical parameters of smart mobile devices and image appearance factors. The procedure and algorithms were applicable to various smart mobile devices, different lighting conditions, and multiple types of images, and performance was verified by the visual data. PMID:25967010

  16. Image quality assessment using multi-method fusion.

    PubMed

    Liu, Tsung-Jung; Lin, Weisi; Kuo, C-C Jay

    2013-05-01

    A new methodology for objective image quality assessment (IQA) with multi-method fusion (MMF) is presented in this paper. The research is motivated by the observation that there is no single method that can give the best performance in all situations. To achieve MMF, we adopt a regression approach. The new MMF score is set to be the nonlinear combination of scores from multiple methods with suitable weights obtained by a training process. In order to improve the regression results further, we divide distorted images into three to five groups based on the distortion types and perform regression within each group, which is called "context-dependent MMF" (CD-MMF). One task in CD-MMF is to determine the context automatically, which is achieved by a machine learning approach. To further reduce the complexity of MMF, we perform algorithms to select a small subset from the candidate method set. The result is very good even if only three quality assessment methods are included in the fusion process. The proposed MMF method using support vector regression is shown to outperform a large number of existing IQA methods by a significant margin when being tested in six representative databases. PMID:23288335

  17. Performance of electronic portal imaging devices (EPIDs) used in radiotherapy: image quality and dose measurements.

    PubMed

    Cremers, F; Frenzel, Th; Kausch, C; Albers, D; Schönborn, T; Schmidt, R

    2004-05-01

    The aim of our study was to compare the image and dosimetric quality of two different imaging systems. The first one is a fluoroscopic electronic portal imaging device (first generation), while the second is based on an amorphous silicon flat-panel array (second generation). The parameters describing image quality include spatial resolution [modulation transfer function (MTF)], noise [noise power spectrum (NPS)], and signal-to-noise transfer [detective quantum efficiency (DQE)]. The dosimetric measurements were compared with ionization chamber as well as with film measurements. The response of the flat-panel imager and the fluoroscopic-optical device was determined performing a two-step Monte Carlo simulation. All measurements were performed in a 6 MV linear accelerator photon beam. The resolution (MTF) of the fluoroscopic device (f 1/2 = 0.3 mm(-1)) is larger than of the amorphous silicon based system (f 1/2 = 0.21 mm(-1)), which is due to the missing backscattered photons and the smaller pixel size. The noise measurements (NPS) show the correlation of neighboring pixels of the amorphous silicon electronic portal imaging device, whereas the NPS of the fluoroscopic system is frequency independent. At zero spatial frequency the DQE of the flat-panel imager has a value of 0.008 (0.8%). Due to the minor frequency dependency this device may be almost x-ray quantum limited. Monte Carlo simulations verified these characteristics. For the fluoroscopic imaging system the DQE at low frequencies is about 0.0008 (0.08%) and degrades with higher frequencies. Dose measurements with the flat-panel imager revealed that images can only be directly converted to portal dose images, if scatter can be neglected. Thus objects distant to the detector (e.g., inhomogeneous dose distribution generated by a modificator) can be verified dosimetrically, while objects close to a detector (e.g., a patient) cannot be verified directly and must be scatter corrected prior to verification. This is

  18. Image quality, tissue heating, and frame rate trade-offs in acoustic radiation force impulse imaging.

    PubMed

    Bouchard, Richard R; Dahl, Jeremy J; Hsu, Stephen J; Palmeri, Mark L; Trahey, Gregg E

    2009-01-01

    The real-time application of acoustic radiation force impulse (ARFI) imaging requires both short acquisition times for a single ARFI image and repeated acquisition of these frames. Due to the high energy of pulses required to generate appreciable radiation force, however, repeated acquisitions could result in substantial transducer face and tissue heating. We describe and evaluate several novel beam sequencing schemes which, along with parallel-receive acquisition, are designed to reduce acquisition time and heating. These techniques reduce the total number of radiation force impulses needed to generate an image and minimize the time between successive impulses. We present qualitative and quantitative analyses of the trade-offs in image quality resulting from the acquisition schemes. Results indicate that these techniques yield a significant improvement in frame rate with only moderate decreases in image quality. Tissue and transducer face heating resulting from these schemes is assessed through finite element method modeling and thermocouple measurements. Results indicate that heating issues can be mitigated by employing ARFI acquisition sequences that utilize the highest track-to-excitation ratio possible. PMID:19213633

  19. Open source database of images DEIMOS: extension for large-scale subjective image quality assessment

    NASA Astrophysics Data System (ADS)

    Vítek, Stanislav

    2014-09-01

    DEIMOS (Database of Images: Open Source) is an open-source database of images and video sequences for testing, verification and comparison of various image and/or video processing techniques such as compression, reconstruction and enhancement. This paper deals with extension of the database allowing performing large-scale web-based subjective image quality assessment. Extension implements both administrative and client interface. The proposed system is aimed mainly at mobile communication devices, taking into account advantages of HTML5 technology; it means that participants don't need to install any application and assessment could be performed using web browser. The assessment campaign administrator can select images from the large database and then apply rules defined by various test procedure recommendations. The standard test procedures may be fully customized and saved as a template. Alternatively the administrator can define a custom test, using images from the pool and other components, such as evaluating forms and ongoing questionnaires. Image sequence is delivered to the online client, e.g. smartphone or tablet, as a fully automated assessment sequence or viewer can decide on timing of the assessment if required. Environmental data and viewing conditions (e.g. illumination, vibrations, GPS coordinates, etc.), may be collected and subsequently analyzed.

  20. Quality Enhancement and Nerve Fibre Layer Artefacts Removal in Retina Fundus Images by Off Axis Imaging

    SciTech Connect

    Giancardo, Luca; Meriaudeau, Fabrice; Karnowski, Thomas Paul; Li, Yaquin; Tobin Jr, Kenneth William; Chaum, Edward

    2011-01-01

    Retinal fundus images acquired with non-mydriatic digital fundus cameras are a versatile tool for the diagnosis of various retinal diseases. Because of the ease of use of newer camera models and their relative low cost, these cameras are employed worldwide by retina specialists to diagnose diabetic retinopathy and other degenerative diseases. Even with relative ease of use, the images produced by these systems sometimes suffer from reflectance artefacts mainly due to the nerve fibre layer (NFL) or other camera lens related reflections. We propose a technique that employs multiple fundus images acquired from the same patient to obtain a single higher quality image without these reflectance artefacts. The removal of bright artefacts, and particularly of NFL reflectance, can have great benefits for the reduction of false positives in the detection of retinal lesions such as exudate, drusens and cotton wool spots by automatic systems or manual inspection. If enough redundant information is provided by the multiple images, this technique also compensates for a suboptimal illumination. The fundus images are acquired in straightforward but unorthodox manner, i.e. the stare point of the patient is changed between each shot but the camera is kept fixed. Between each shot, the apparent shape and position of all the retinal structures that do not exhibit isotropic reflectance (e.g. bright artefacts) change. This physical effect is exploited by our algorithm in order to extract the pixels belonging to the inner layers of the retina, hence obtaining a single artefacts-free image.

  1. Human vision model for the objective evaluation of perceived image quality applied to MRI and image restoration

    NASA Astrophysics Data System (ADS)

    Salem, Kyle A.; Wilson, David L.

    2002-12-01

    We are developing a method to objectively quantify image quality and applying it to the optimization of interventional magnetic resonance imaging (iMRI). In iMRI, images are used for live-time guidance of interventional procedures such as the minimally invasive treatment of cancer. Hence, not only does one desire high quality images, but they must also be acquired quickly. In iMRI, images are acquired in the Fourier domain, or k-space, and this allows many creative ways to image quickly such as keyhole imaging where k-space is preferentially subsampled, yielding suboptimal images at very high frame rates. Other techniques include spiral, radial, and the combined acquisition technique. We have built a perceptual difference model (PDM) that incorporates various components of the human visual system. The PDM was validated using subjective image quality ratings by naive observers and task-based measures defined by interventional radiologists. Using the PDM, we investigated the effects of various imaging parameters on image quality and quantified the degradation due to novel imaging techniques. Results have provided significant information about imaging time versus quality tradeoffs aiding the MR sequence engineer. The PDM has also been used to evaluate other applications such as Dixon fat suppressed MRI and image restoration. In image restoration, the PDM has been used to evaluate the Generalized Minimal Residual (GMRES) image restoration method and to examine the ability to appropriately determine a stopping condition for such iterative methods. The PDM has been shown to be an objective tool for measuring image quality and can be used to determine the optimal methodology for various imaging applications.

  2. Diffusion imaging quality control via entropy of principal direction distribution.

    PubMed

    Farzinfar, Mahshid; Oguz, Ipek; Smith, Rachel G; Verde, Audrey R; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C; Paterson, Sarah; Evans, Alan C; Styner, Martin A

    2013-11-15

    Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, "venetian blind" artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here called

  3. Diffusion imaging quality control via entropy of principal direction distribution

    PubMed Central

    Oguz, Ipek; Smith, Rachel G.; Verde, Audrey R.; Dietrich, Cheryl; Gupta, Aditya; Escolar, Maria L.; Piven, Joseph; Pujol, Sonia; Vachet, Clement; Gouttard, Sylvain; Gerig, Guido; Dager, Stephen; McKinstry, Robert C.; Paterson, Sarah; Evans, Alan C.; Styner, Martin A.

    2013-01-01

    Diffusion MR imaging has received increasing attention in the neuroimaging community, as it yields new insights into the microstructural organization of white matter that are not available with conventional MRI techniques. While the technology has enormous potential, diffusion MRI suffers from a unique and complex set of image quality problems, limiting the sensitivity of studies and reducing the accuracy of findings. Furthermore, the acquisition time for diffusion MRI is longer than conventional MRI due to the need for multiple acquisitions to obtain directionally encoded Diffusion Weighted Images (DWI). This leads to increased motion artifacts, reduced signal-to-noise ratio (SNR), and increased proneness to a wide variety of artifacts, including eddy-current and motion artifacts, “venetian blind” artifacts, as well as slice-wise and gradient-wise inconsistencies. Such artifacts mandate stringent Quality Control (QC) schemes in the processing of diffusion MRI data. Most existing QC procedures are conducted in the DWI domain and/or on a voxel level, but our own experiments show that these methods often do not fully detect and eliminate certain types of artifacts, often only visible when investigating groups of DWI's or a derived diffusion model, such as the most-employed diffusion tensor imaging (DTI). Here, we propose a novel regional QC measure in the DTI domain that employs the entropy of the regional distribution of the principal directions (PD). The PD entropy quantifies the scattering and spread of the principal diffusion directions and is invariant to the patient's position in the scanner. High entropy value indicates that the PDs are distributed relatively uniformly, while low entropy value indicates the presence of clusters in the PD distribution. The novel QC measure is intended to complement the existing set of QC procedures by detecting and correcting residual artifacts. Such residual artifacts cause directional bias in the measured PD and here

  4. Assessment of processes affecting low-flow water quality of Cedar Creek, west-central Illinois

    USGS Publications Warehouse

    Schmidt, Arthur R.; Freeman, W.O.; McFarlane, R.D.

    1989-01-01

    Water quality and the processes that affect dissolved oxygen, nutrient (nitrogen and phosphorus species), and algal concentrations were evaluated for a 23.8-mile reach of Cedar Creek near Galesburg, west-central Illinois, during periods of warm-weather, low-flow conditions. Water quality samples were collected and stream conditions were measured over a diel (24 hour) period on three occasions during July and August 1985. Analysis of data from the diel-sampling periods indicates that concentrations of iron, copper, manganese, phenols, and total dissolved-solids exceeded Illinois ' general-use water quality standards in some locations. Dissolved-oxygen concentrations were less than the State minimum standard throughout much of the study reach. These data were used to calibrate and verify a one-dimensional, steady-state, water quality model. The computer model was used to assess the relative effects on low-flow water quality of processes such as algal photosynthesis and respiration, ammonia oxidation, biochemical oxygen demand, sediment oxygen demand, and stream reaeration. Results from model simulations and sensitivity analysis indicate that sediment oxygen demand is the principal cause of low dissolved-oxygen concentrations in the creek. (USGS)

  5. How visual images of chocolate affect the craving and guilt of female dieters.

    PubMed

    Fletcher, Ben C; Pine, Karen J; Woodbridge, Zoe; Nash, Avril

    2007-03-01

    This study asks whether exposure to images of chocolate induces cravings and guilty feelings in females. A further aim was to examine whether these effects are heightened in the case of dieters. The participants, 85 females, saw a series of enticing media images, either of chocolate or of non-food products. Two thirds of the sample were dieting or had dieted in the past; 15% had been on seven or more diets. After viewing the images all participants completed the Attitudes to Chocolate Questionnaire (ACQ) [Benton, Greenfield, & Morgan (1998). The development of the attitudes to chocolate questionnaire. Personality and Individual Differences, 24(4), 513-520]. The different conditions affected only those who dieted. Dieters had significantly higher ACQ scores after viewing the chocolate images than the non-dieters. It is suggested that dietary restriction increases desire for forbidden foods, in the form of craving, and may induce negative affect such as guilt, anxiety and depression. PMID:17055111

  6. A widefield fluorescence microscope with a linear image sensor for image cytometry of biospecimens: Considerations for image quality optimization

    NASA Astrophysics Data System (ADS)

    Hutcheson, Joshua A.; Majid, Aneeka A.; Powless, Amy J.; Muldoon, Timothy J.

    2015-09-01

    Linear image sensors have been widely used in numerous research and industry applications to provide continuous imaging of moving objects. Here, we present a widefield fluorescence microscope with a linear image sensor used to image translating objects for image cytometry. First, a calibration curve was characterized for a custom microfluidic chamber over a span of volumetric pump rates. Image data were also acquired using 15 μm fluorescent polystyrene spheres on a slide with a motorized translation stage in order to match linear translation speed with line exposure periods to preserve the image aspect ratio. Aspect ratios were then calculated after imaging to ensure quality control of image data. Fluorescent beads were imaged in suspension flowing through the microfluidics chamber being pumped by a mechanical syringe pump at 16 μl min-1 with a line exposure period of 150 μs. The line period was selected to acquire images of fluorescent beads with a 40 dB signal-to-background ratio. A motorized translation stage was then used to transport conventional glass slides of stained cellular biospecimens. Whole blood collected from healthy volunteers was stained with 0.02% (w/v) proflavine hemisulfate was imaged to highlight leukocyte morphology with a 1.56 mm × 1.28 mm field of view (1540 ms total acquisition time). Oral squamous cells were also collected from healthy volunteers and stained with 0.01% (w/v) proflavine hemisulfate to demonstrate quantifiable subcellular features and an average nuclear to cytoplasmic ratio of 0.03 (n = 75), with a resolution of 0.31 μm pixels-1.

  7. A widefield fluorescence microscope with a linear image sensor for image cytometry of biospecimens: Considerations for image quality optimization.

    PubMed

    Hutcheson, Joshua A; Majid, Aneeka A; Powless, Amy J; Muldoon, Timothy J

    2015-09-01

    Linear image sensors have been widely used in numerous research and industry applications to provide continuous imaging of moving objects. Here, we present a widefield fluorescence microscope with a linear image sensor used to image translating objects for image cytometry. First, a calibration curve was characterized for a custom microfluidic chamber over a span of volumetric pump rates. Image data were also acquired using 15 μm fluorescent polystyrene spheres on a slide with a motorized translation stage in order to match linear translation speed with line exposure periods to preserve the image aspect ratio. Aspect ratios were then calculated after imaging to ensure quality control of image data. Fluorescent beads were imaged in suspension flowing through the microfluidics chamber being pumped by a mechanical syringe pump at 16 μl min(-1) with a line exposure period of 150 μs. The line period was selected to acquire images of fluorescent beads with a 40 dB signal-to-background ratio. A motorized translation stage was then used to transport conventional glass slides of stained cellular biospecimens. Whole blood collected from healthy volunteers was stained with 0.02% (w/v) proflavine hemisulfate was imaged to highlight leukocyte morphology with a 1.56 mm × 1.28 mm field of view (1540 ms total acquisition time). Oral squamous cells were also collected from healthy volunteers and stained with 0.01% (w/v) proflavine hemisulfate to demonstrate quantifiable subcellular features and an average nuclear to cytoplasmic ratio of 0.03 (n = 75), with a resolution of 0.31 μm pixels(-1). PMID:26429450

  8. A widefield fluorescence microscope with a linear image sensor for image cytometry of biospecimens: Considerations for image quality optimization

    SciTech Connect

    Hutcheson, Joshua A.; Majid, Aneeka A.; Powless, Amy J.; Muldoon, Timothy J.

    2015-09-15

    Linear image sensors have been widely used in numerous research and industry applications to provide continuous imaging of moving objects. Here, we present a widefield fluorescence microscope with a linear image sensor used to image translating objects for image cytometry. First, a calibration curve was characterized for a custom microfluidic chamber over a span of volumetric pump rates. Image data were also acquired using 15 μm fluorescent polystyrene spheres on a slide with a motorized translation stage in order to match linear translation speed with line exposure periods to preserve the image aspect ratio. Aspect ratios were then calculated after imaging to ensure quality control of image data. Fluorescent beads were imaged in suspension flowing through the microfluidics chamber being pumped by a mechanical syringe pump at 16 μl min{sup −1} with a line exposure period of 150 μs. The line period was selected to acquire images of fluorescent beads with a 40 dB signal-to-background ratio. A motorized translation stage was then used to transport conventional glass slides of stained cellular biospecimens. Whole blood collected from healthy volunteers was stained with 0.02% (w/v) proflavine hemisulfate was imaged to highlight leukocyte morphology with a 1.56 mm × 1.28 mm field of view (1540 ms total acquisition time). Oral squamous cells were also collected from healthy volunteers and stained with 0.01% (w/v) proflavine hemisulfate to demonstrate quantifiable subcellular features and an average nuclear to cytoplasmic ratio of 0.03 (n = 75), with a resolution of 0.31 μm pixels{sup −1}.

  9. Beyond image quality: designing engaging interactions with digital products

    NASA Astrophysics Data System (ADS)

    de Ridder, Huib; Rozendaal, Marco C.

    2008-02-01

    Ubiquitous computing (or Ambient Intelligence) promises a world in which information is available anytime anywhere and with which humans can interact in a natural, multimodal way. In such world, perceptual image quality remains an important criterion since most information will be displayed visually, but other criteria such as enjoyment, fun, engagement and hedonic quality are emerging. This paper deals with engagement, the intrinsically enjoyable readiness to put more effort into exploring and/or using a product than strictly required, thus attracting and keeping user's attention for a longer period of time. The impact of the experienced richness of an interface, both visually and degree of possible manipulations, was investigated in a series of experiments employing game-like user interfaces. This resulted in the extension of an existing conceptual framework relating engagement to richness by means of two intermediating variables, namely experienced challenge and sense of control. Predictions from this revised framework are evaluated against results of an earlier experiment assessing the ergonomic and hedonic qualities of interactive media. Test material consisted of interactive CD-ROM's containing presentations of three companies for future customers.

  10. Comparison of no-reference image quality assessment machine learning-based algorithms on compressed images

    NASA Astrophysics Data System (ADS)

    Charrier, Christophe; Saadane, AbdelHakim; Fernandez-Maloigne, Christine

    2015-01-01

    No-reference image quality metrics are of fundamental interest as they can be embedded in practical applications. The main goal of this paper is to perform a comparative study of seven well known no-reference learning-based image quality algorithms. To test the performance of these algorithms, three public databases are used. As a first step, the trial algorithms are compared when no new learning is performed. The second step investigates how the training set influences the results. The Spearman Rank Ordered Correlation Coefficient (SROCC) is utilized to measure and compare the performance. In addition, an hypothesis test is conducted to evaluate the statistical significance of performance of each tested algorithm.

  11. Joint influences of aerodynamic flow field and aerodynamic heating of the dome on imaging quality degradation of airborne optical systems.

    PubMed

    Xiao, Haosu; Zuo, Baojun; Tian, Yi; Zhang, Wang; Hao, Chenglong; Liu, Chaofeng; Li, Qi; Li, Fan; Zhang, Li; Fan, Zhigang

    2012-12-20

    We investigated the joint influences exerted by the nonuniform aerodynamic flow field surrounding the optical dome and the aerodynamic heating of the dome on imaging quality degradation of an airborne optical system. The Spalart-Allmaras model provided by FLUENT was used for flow computations. The fourth-order Runge-Kutta algorithm based ray tracing program was used to simulate optical transmission through the aerodynamic flow field and the dome. Four kinds of imaging quality evaluation parameters were presented: wave aberration of the exit pupil, point spread function, encircled energy, and modulation transfer function. The results show that the aero-optical disturbance of the aerodynamic flow field and the aerodynamic heating of the dome significantly affect the imaging quality of an airborne optical system. PMID:23262604

  12. Comprehensive analysis of imaging quality degradation of an airborne optical system for aerodynamic flow field around the optical window.

    PubMed

    Hao, Chenglong; Chen, Shouqian; Zhang, Wang; Ren, Jinhan; Li, Chong; Pang, Hongjun; Wang, Honghao; Liu, Qian; Wang, Chao; Zou, Huiying; Fan, Zhigang

    2013-11-20

    We investigated the influences exerted by the nonuniform aerodynamic flow field surrounding the optical window on the imaging quality degradation of an airborne optical system. The density distribution of flow fields around three typical optical windows, including a spherical window, an ellipsoidal window, and a paraboloidal window, were calculated by adopting the Reynolds-averaged Navier-Stokes equations with the Spalart-Allmaras model provided by FLUENT. The fourth-order Runge-Kutta algorithm based ray-tracing program was used to simulate the optical transmission through the aerodynamic flow field. Four kinds of imaging quality evaluation parameters were presented: wave aberration of the entrance pupil, point spread function, encircled energy, and modulation transfer function. The results show that the imaging quality of the airborne optical system was affected by the shape of the optical window and angle of attack of the aircraft. PMID:24513738

  13. Content-weighted video quality assessment using a three-component image model

    NASA Astrophysics Data System (ADS)

    Li, Chaofeng; Bovik, Alan Conrad

    2010-01-01

    Objective image and video quality measures play important roles in numerous image and video processing applications. In this work, we propose a new content-weighted method for full-reference (FR) video quality assessment using a three-component image model. Using the idea that different image regions have different perceptual significance relative to quality, we deploy a model that classifies image local regions according to their image gradient properties, then apply variable weights to structural similarity image index (SSIM) [and peak signal-to-noise ratio (PSNR)] scores according to region. A frame-based video quality assessment algorithm is thereby derived. Experimental results on the Video Quality Experts Group (VQEG) FR-TV Phase 1 test dataset show that the proposed algorithm outperforms existing video quality assessment methods.

  14. Characterizing image quality in a scanning laser ophthalmoscope with differing pinholes and induced scattered light

    NASA Astrophysics Data System (ADS)

    Hunter, Jennifer J.; Cookson, Christopher J.; Kisilak, Marsha L.; Bueno, Juan M.; Campbell, Melanie C. W.

    2007-05-01

    We quantify the effects on scanning laser ophthalmoscope image quality of controlled amounts of scattered light, confocal pinhole diameter, and age. Optical volumes through the optic nerve head were recorded for a range of pinhole sizes in 12 subjects (19-64 years). The usefulness of various overall metrics in quantifying the changes in fundus image quality is assessed. For registered and averaged images, we calculated signal-to-noise ratio, entropy, and acutance. Entropy was best able to distinguish differing image quality. The optimum confocal pinhole diameter was found to be 50 μm (on the retina), providing improved axial resolution and image quality under all conditions.

  15. Image Quality Performance Measurement of the microPET Focus 120

    NASA Astrophysics Data System (ADS)

    Ballado, Fernando Trejo; López, Nayelli Ortega; Flores, Rafael Ojeda; Ávila-Rodríguez, Miguel A.

    2010-12-01

    The aim of this work is to evaluate the characteristics involved in the image reconstruction of the microPET Focus 120. For this evaluation were used two different phantoms; a miniature hot-rod Derenzo phantom and a National Electrical Manufacturers Association (NEMA) NU4-2008 image quality (IQ) phantom. The best image quality was obtained when using OSEM3D as the reconstruction method reaching a spatial resolution of 1.5 mm with the Derenzo phantom filled with 18F. Image quality test results indicate a superior image quality for the Focus 120 when compared to previous microPET models.

  16. The imaging viewpoint: how imaging affects determination of progression-free survival.

    PubMed

    Sullivan, Daniel Carl; Schwartz, Lawrence H; Zhao, Binsheng

    2013-05-15

    Tumor measurements on computed tomgoraphic or MRI scans and/or the appearance of new lesions on any of a variety of imaging studies including positron emission tomographic scans are key determinants for assessing progression-free survival as an endpoint in many clinical trials of therapies for solid tumors. Test-retest tumor measurement reproducibility may vary considerably across serial scans on the same patient unless rigorous attention is paid to standardization of image acquisition parameters and unless measurements are made by trained, experienced observers using validated objective methods. Target lesion selection also must be done with care to choose lesions that are or will be reproducibly measurable. Likewise, new lesions will be missed or misinterpreted on follow-up imaging studies unless those imaging studies are obtained using techniques suitable for detecting early, small lesions. Reader variability is clearly a major component of the problem. The increasing availability of semiautomatic image processing algorithms will help ameliorate that issue. In addition, an array of internationally accepted guidelines, standards, and accreditation programs now exist to help address these problems. PMID:23669422

  17. Task-based measures of image quality and their relation to radiation dose and patient risk

    PubMed Central

    Barrett, Harrison H.; Myers, Kyle J.; Hoeschen, Christoph; Kupinski, Matthew A.; Little, Mark P.

    2015-01-01

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality. PMID:25564960

  18. Task-based measures of image quality and their relation to radiation dose and patient risk

    NASA Astrophysics Data System (ADS)

    Barrett, Harrison H.; Myers, Kyle J.; Hoeschen, Christoph; Kupinski, Matthew A.; Little, Mark P.

    2015-01-01

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality.

  19. Task-based measures of image quality and their relation to radiation dose and patient risk.

    PubMed

    Barrett, Harrison H; Myers, Kyle J; Hoeschen, Christoph; Kupinski, Matthew A; Little, Mark P

    2015-01-21

    The theory of task-based assessment of image quality is reviewed in the context of imaging with ionizing radiation, and objective figures of merit (FOMs) for image quality are summarized. The variation of the FOMs with the task, the observer and especially with the mean number of photons recorded in the image is discussed. Then various standard methods for specifying radiation dose are reviewed and related to the mean number of photons in the image and hence to image quality. Current knowledge of the relation between local radiation dose and the risk of various adverse effects is summarized, and some graphical depictions of the tradeoffs between image quality and risk are introduced. Then various dose-reduction strategies are discussed in terms of their effect on task-based measures of image quality. PMID:25564960

  20. SENTINEL-2 image quality and level 1 processing

    NASA Astrophysics Data System (ADS)

    Meygret, Aimé; Baillarin, Simon; Gascon, Ferran; Hillairet, Emmanuel; Dechoz, Cécile; Lacherade, Sophie; Martimort, Philippe; Spoto, François; Henry, Patrice; Duca, Riccardo

    2009-08-01

    In the framework of the Global Monitoring for Environment and Security (GMES) programme, the European Space Agency (ESA) in partnership with the European Commission (EC) is developing the SENTINEL-2 optical imaging mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a twin satellites configuration deployed in polar sun-synchronous orbit and is designed to offer a unique combination of systematic global coverage with a wide field of view (290km), a high revisit (5 days at equator with two satellites), a high spatial resolution (10m, 20m and 60 m) and multi-spectral imagery (13 bands in the visible and the short wave infrared spectrum). SENTINEL-2 will ensure data continuity of SPOT and LANDSAT multispectral sensors while accounting for future service evolution. This paper presents the main geometric and radiometric image quality requirements for the mission. The strong multi-spectral and multi-temporal registration requirements constrain the stability of the platform and the ground processing which will automatically refine the geometric physical model through correlation technics. The geolocation of the images will take benefits from a worldwide reference data set made of SENTINEL-2 data strips geolocated through a global space-triangulation. These processing are detailed through the description of the level 1C production which will provide users with ortho-images of Top of Atmosphere reflectances. The huge amount of data (1.4 Tbits per orbit) is also a challenge for the ground processing which will produce at level 1C all the acquired data. Finally we discuss the different geometric (line of sight, focal plane cartography, ...) and radiometric (relative and absolute camera sensitivity) in-flight calibration methods that will take advantage of the on-board sun diffuser and ground targets to answer the severe mission requirements.

  1. Dual-source computed tomographic coronary angiography: image quality and stenosis diagnosis in patients with high heart rates.

    PubMed

    Zheng, Minwen; Li, Jiayi; Xu, Jian; Chen, Kang; Zhao, Hongliang; Huan, Yi

    2009-01-01

    We sought to evaluate prospectively the effects of heart rate and heart-rate variability on dual-source computed tomographic coronary image quality in patients whose heart rates were high, and to determine retrospectively the accuracy of dual-source computed tomographic diagnosis of coronary artery stenosis in the same patients.We compared image quality and diagnostic accuracy in 40 patients whose heart rates exceeded 70 beats/min with the same data in 40 patients whose heart rates were 70 beats/min or slower. In both groups, we analyzed 1,133 coronary arterial segments. Five hundred forty-five segments (97.7%) in low-heart-rate patients and 539 segments (93.7%) in high-heart-rate patients were of diagnostic image quality. We considered P < 0.05 to be statistically significant. No statistically significant differences between the groups were found in diagnostic-image quality scores of total segments or of any coronary artery, nor were any significant differences found between the groups in the accurate diagnosis of angiographically significant stenosis.Calcification was the chief factor that affected diagnostic accuracy. In high-heart-rate patients, heart-rate variability was significantly related to the diagnostic image quality of all segments (P = 0.001) and of the left circumflex coronary artery (P = 0.016). Heart-rate variability of more than 5 beats/min most strongly contributed to an inability to evaluate segments in both groups. When heart rates rose, the optimal reconstruction window shifted from diastole to systole.The image quality of dual-source computed tomographic coronary angiography at high heart rates enables sufficient diagnosis of stenosis, although variability of heart rates significantly deteriorates image quality. PMID:19436804

  2. Mutual information as a measure of image quality for 3D dynamic lung imaging with EIT

    PubMed Central

    Crabb, M G; Davidson, J L; Little, R; Wright, P; Morgan, A R; Miller, C A; Naish, J H; Parker, G J M; Kikinis, R; McCann, H; Lionheart, W R B

    2014-01-01

    We report on a pilot study of dynamic lung electrical impedance tomography (EIT) at the University of Manchester. Low-noise EIT data at 100 frames per second (fps) were obtained from healthy male subjects during controlled breathing, followed by magnetic resonance imaging (MRI) subsequently used for spatial validation of the EIT reconstruction. The torso surface in the MR image and electrode positions obtained using MRI fiducial markers informed the construction of a 3D finite element model extruded along the caudal-distal axis of the subject. Small changes in the boundary that occur during respiration were accounted for by incorporating the sensitivity with respect to boundary shape into a robust temporal difference reconstruction algorithm. EIT and MRI images were co-registered using the open source medical imaging software, 3D Slicer. A quantitative comparison of quality of different EIT reconstructions was achieved through calculation of the mutual information with a lung-segmented MR image. EIT reconstructions using a linear shape correction algorithm reduced boundary image artefacts, yielding better contrast of the lungs, and had 10% greater mutual information compared with a standard linear EIT reconstruction. PMID:24710978

  3. Sparse Representation-Based Image Quality Index With Adaptive Sub-Dictionaries.

    PubMed

    Li, Leida; Cai, Hao; Zhang, Yabin; Lin, Weisi; Kot, Alex C; Sun, Xingming

    2016-08-01

    Distortions cause structural changes in digital images, leading to degraded visual quality. Dictionary-based sparse representation has been widely studied recently due to its ability to extract inherent image structures. Meantime, it can extract image features with slightly higher level semantics. Intuitively, sparse representation can be used for image quality assessment, because visible distortions can cause significant changes to the sparse features. In this paper, a new sparse representation-based image quality assessment model is proposed based on the construction of adaptive sub-dictionaries. An overcomplete dictionary trained from natural images is employed to capture the structure changes between the reference and distorted images by sparse feature extraction via adaptive sub-dictionary selection. Based on the observation that image sparse features are invariant to weak degradations and the perceived image quality is generally influenced by diverse issues, three auxiliary quality features are added, including gradient, color, and luminance information. The proposed method is not sensitive to training images, so a universal dictionary can be adopted for quality evaluation. Extensive experiments on five public image quality databases demonstrate that the proposed method produces the state-of-the-art results, and it delivers consistently well performances when tested in different image quality databases. PMID:27295675

  4. Genetic and management factors affecting beef quality in grazing Hereford steers.

    PubMed

    Melucci, L M; Panarace, M; Feula, P; Villarreal, E L; Grigioni, G; Carduza, F; Soria, L A; Mezzadra, C A; Arceo, M E; Papaleo Mazzucco, J; Corva, P M; Irurueta, M; Rogberg-Muñoz, A; Miquel, M C

    2012-12-01

    Attributes contributing to differences in beef quality of 206 Hereford steers finished on pasture were assessed. Beef quality traits evaluated were: Warner-Bratzler meat tenderness and muscle and fat color at one and seven days after slaughter and trained sensory panel traits (tenderness, juiciness, flavor, and marbling) at seven days. Molecular markers were CAPN1 316 and an SNP in exon 2 on the leptin gene (E2FB). Average daily live weight gain, ultrasound monthly backfat thickness gain and rib-eye area gain were estimated. Molecular markers effects on meat quality traits were analyzed by mixed models. Association of meat quality with post weaning growth traits was analyzed by canonical correlations. Muscle color and marbling were affected by CAPN1 316 and E2FB and Warner-Bratzler meat tenderness by the former. The results confirm that marker assisted selection for tenderness is advisable only when beef aging is a common practice. The most important sources of variation in tenderness and color of meat remained unaccounted for. PMID:22818350

  5. Factors Affecting the Quality of Life and the Illness Acceptance of Pregnant Women with Diabetes

    PubMed Central

    Bień, Agnieszka; Rzońca, Ewa; Kańczugowska, Angelika; Iwanowicz-Palus, Grażyna

    2015-01-01

    The paper contains an analysis of the factors affecting the quality of life (QoL) and the illness acceptance of diabetic pregnant women. The study was performed between January and April, 2013. It included 114 pregnant women with diabetes, hospitalized in the High Risk Pregnancy Wards of several hospitals in Lublin, Poland. The study used a diagnostic survey with questionnaires. The research instruments used were: The WHOQOL-Bref questionnaire and the Acceptance of Illness Scale (AIS). The women’s general quality of life was slightly higher than their perceived general health. A higher quality of life was reported by women with a very good financial standing, very good perceived health, moderate self-reported knowledge of diabetes, and also by those only treated with diet and stating that the illness did not interfere with their lives (p < 0.05). Women with a very good financial standing (p < 0.009), high self-reported health (p < 0.002), and those treated with by means of a diet (p < 0.04) had a higher acceptance of illness. A higher acceptance of illness contributes to a higher general quality of life and a better perception of one’s health. PMID:26703697

  6. Lead level in seminal plasma may affect semen quality for men without occupational exposure to lead

    PubMed Central

    2012-01-01

    Background Infertility affects approximately 10–15% of reproductive-age couples. Poor semen quality contributes to about 25% of infertile cases. Resulting from the direct effect on testicular function or hormonal alterations, heavy metals exposure has been related to impaired semen quality. The objective of this study was to assess the level of lead in the seminal plasma in men without occupational exposure to lead, and to determine the relationship between semen quality and lead concentration in the semen. Methods This is a prospective and nonrandomized clinical study conducted in University infertility clinic and academic research laboratory. Three hundred and forty-one male partners of infertile couples undergoing infertility evaluation and management were recruited to the study. Semen samples collected for the analyses of semen quality were also used for the measurement of lead concentrations. Semen samples were evaluated according to the WHO standards. Results All subjects were married and from infertile couples without occupational exposure to lead. There is a significant inverse correlation between the lead concentration in seminal plasma and sperm count. A higher semen lead concentration was correlated with lower sperm count, but not with semen volume, sperm motility or sperm morphology as assessed by simple linear regression. Conclusions We found that semen lead concentration was significantly higher among the patients with lower sperm count. To our knowledge, this is the first study to demonstrate that a high level of lead accumulation in semen may reduce the sperm count contributing to infertility of men without occupational exposure to lead. PMID:23137356

  7. Does Time Affect Patient Satisfaction and Health-Related Quality of Life After Reduction Mammoplasty?

    PubMed Central

    Cohen, Wess A.; Homel, Peter

    2016-01-01

    Objective: A total of 62,611 patients with breast hypertrophy underwent breast reduction surgery in 2013 in the United States to improve their symptoms and health-related quality of life. While multiple studies utilizing various outcome instruments demonstrate the efficacy of reductive surgery, it is presently unknown how the postoperative course affects patient satisfaction and health-related quality of life as measured by the BREAST-Q. Our objective was to determine the temporal relationship of patient satisfaction and health-related quality of life after reduction mammoplasty. Methods: Patients prospectively completed the BREAST-Q reduction mammoplasty module at 3 time points during their treatment: preoperatively, at less than 3 months postoperatively, and at more than 3 months (<12 months) postoperatively. A single surgeon (N.P.P.) performed all of the breast reduction procedures. Results: Each time point contained 20 questionnaires. Mean preoperative BREAST-Q scores were significantly lower than scores at the less than 3-month postoperative time point for the scales Satisfaction With Breasts, Psychosocial Well-being, Sexual Well-being, and Physical Well-being (P < .001). There was no significant difference in BREAST-Q scores between the postoperative time points in these measures. Conclusion: Breast reduction surgery offers a vast improvement in patients’ satisfaction and health-related quality of life that is maintained throughout the postoperative period. These findings can assist surgeons in managing patient expectations after reduction mammoplasty and help improve the probability of obtaining prior authorization for insurance coverage. PMID:26819650

  8. Is Rural School-aged Children's Quality of Life Affected by Their Responses to Asthma?

    PubMed Central

    Horner, Sharon D.; Brown, Sharon A.; Walker, Veronica García

    2011-01-01

    The unpredictable nature of asthma makes it stressful for children and can affect their quality of life. An exploratory analysis of 183 rural school-aged children's data was conducted to determine relationships among demographic factors, children's responses to asthma (coping, asthma self-management), and their quality of life (QOL). Coping frequency, asthma severity, and race/ethnicity significantly predicted children's asthma-related QOL. Children reported more frequent coping as asthma-related QOL worsened (higher scores). Children with more asthma severity had worse asthma-related QOL. Post-hoc analyses showed that racial/ethnic minorities reported worse asthma-related QOL scores than did non-Hispanic Whites. PMID:22920660

  9. Mindfulness and dream quality: the inverse relationship between mindfulness and negative dream affect.

    PubMed

    Simor, Péter; Köteles, Ferenc; Sándor, Piroska; Petke, Zsolt; Bódizs, Róbert

    2011-08-01

    The aim of the study was to examine the relationship of mindfulness to the emotional quality of dreaming. In our questionnaire-based study, comprising the data of 587 undergraduate students we examined the association between trait anxiety, perceived stress, trait mindfulness, negative dream affect and dream anxiety. Our results indicate that mindfulness is inversely related to disturbed dreaming and predicts less severe dream disturbances after controlling for trait anxiety. Moreover, the results of the applied hierarchical regression analysis suggest that mindfulness is associated with reduced dream anxiety by moderating the extent of waking anxiety. Our findings extend previous research relating mindfulness, emotional regulation and sleep quality to the domain of dream research. We suggest that mindfulness is a possible protective factor against dream disturbances. PMID:21504431

  10. Investigation of the effect of subcutaneous fat on image quality performance of 2D conventional imaging and tissue harmonic imaging.

    PubMed

    Browne, Jacinta E; Watson, Amanda J; Hoskins, Peter R; Elliott, Alex T

    2005-07-01

    Tissue harmonic imaging (THI) has been reported to improve contrast resolution, tissue differentiation and overall image quality in clinical examinations. However, a study carried out previously by the authors (Brown et al. 2004) found improvements only in spatial resolution and not in contrast resolution or anechoic target detection. This result may have been due to the homogeneity of the phantom. Biologic tissues are generally inhomogeneous and THI has been reported to improve image quality in the presence of large amounts of subcutaneous fat. The aims of the study were to simulate the distortion caused by subcutaneous fat to image quality and thus investigate further the improvements reported in anechoic target detection and contrast resolution performance with THI compared with 2D conventional imaging. In addition, the effect of three different types of fat-mimicking layer on image quality was examined. The abdominal transducer of two ultrasound scanners with 2D conventional imaging and THI were tested, the 4C1 (Aspen-Acuson, Siemens Co., CA, USA) and the C5-2 (ATL HDI 5000, ATL/Philips, Amsterdam, The Netherlands). An ex vivo subcutaneous pig fat layer was used to replicate beam distortion and phase aberration seen clinically in the presence of subcutaneous fat. Three different types of fat-mimicking layers (olive oil, lard and lard with fish oil capsules) were evaluated. The subcutaneous pig fat layer demonstrated an improvement in anechoic target detection with THI compared with 2D conventional imaging, but no improvement was demonstrated in contrast resolution performance; a similar result was found in a previous study conducted by this research group (Brown et al. 2004) while using this tissue-mimicking phantom without a fat layer. Similarly, while using the layers of olive oil, lard and lard with fish oil capsules, improvements due to THI were found in anechoic target detection but, again, no improvements were found for contrast resolution for any of the

  11. Advancing the Quality of Solar Occultation Retrievals through Solar Imaging

    NASA Astrophysics Data System (ADS)

    Gordley, L. L.; Hervig, M. E.; Marshall, B. T.; Russell, J. E.; Bailey, S. M.; Brown, C. W.; Burton, J. C.; Deaver, L. E.; Magill, B. E.; McHugh, M. J.; Paxton, G. J.; Thompson, R. E.

    2008-12-01

    The quality of retrieved profiles (e.g. mixing ratio, temperature, pressure, and extinction) from solar occultation sensors is strongly dependent on the angular fidelity of the measurements. The SOFIE instrument, launched on-board the AIM (Aeronomy of Ice in the Mesosphere) satellite on April 25, 2007, was designed to provide very high precision broadband measurements for the study of Polar Mesospheric Clouds (PMCs), that appear near 83km, just below the high latitude summer mesopause. The SOFIE instrument achieves an unprecedented angular fidelity by imaging the sun on a 2D detector array and tracking the edges with an uncertainty of <0.1 arc seconds. This makes possible retrieved profiles of vertical high resolution mixing ratios, refraction base temperature and pressure from tropopause to lower mesosphere, and transmission with accuracy sufficient to infer cosmic smoke extinction. Details of the approach and recent results will be presented.

  12. The image quality of ion computed tomography at clinical imaging dose levels

    SciTech Connect

    Hansen, David C.; Bassler, Niels; Sørensen, Thomas Sangild; Seco, Joao

    2014-11-01

    Purpose: Accurately predicting the range of radiotherapy ions in vivo is important for the precise delivery of dose in particle therapy. Range uncertainty is currently the single largest contribution to the dose margins used in planning and leads to a higher dose to normal tissue. The use of ion CT has been proposed as a method to improve the range uncertainty and thereby reduce dose to normal tissue of the patient. A wide variety of ions have been proposed and studied for this purpose, but no studies evaluate the image quality obtained with different ions in a consistent manner. However, imaging doses ion CT is a concern which may limit the obtainable image quality. In addition, the imaging doses reported have not been directly comparable with x-ray CT doses due to the different biological impacts of ion radiation. The purpose of this work is to develop a robust methodology for comparing the image quality of ion CT with respect to particle therapy, taking into account different reconstruction methods and ion species. Methods: A comparison of different ions and energies was made. Ion CT projections were simulated for five different scenarios: Protons at 230 and 330 MeV, helium ions at 230 MeV/u, and carbon ions at 430 MeV/u. Maps of the water equivalent stopping power were reconstructed using a weighted least squares method. The dose was evaluated via a quality factor weighted CT dose index called the CT dose equivalent index (CTDEI). Spatial resolution was measured by the modulation transfer function. This was done by a noise-robust fit to the edge spread function. Second, the image quality as a function of the number of scanning angles was evaluated for protons at 230 MeV. In the resolution study, the CTDEI was fixed to 10 mSv, similar to a typical x-ray CT scan. Finally, scans at a range of CTDEI’s were done, to evaluate dose influence on reconstruction error. Results: All ions yielded accurate stopping power estimates, none of which were statistically

  13. Terahertz absorption and reflection imaging of carcinoma-affected colon tissues embedded in paraffin

    NASA Astrophysics Data System (ADS)

    Wahaia, Faustino; Kasalynas, Irmantas; Venckevicius, Rimvydas; Seliuta, Dalius; Valusis, Gintaras; Urbanowicz, Andrzej; Molis, Gediminas; Carneiro, Fatima; Carvalho Silva, Catia D.; Granja, Pedro L.

    2016-03-01

    In the present study, dehydrated human colon tissues embedded in paraffin were studied at THz frequency. A compact THz imaging system with high numerical aperture optics was developed for the analysis of adenocarcinoma-affected colon sections, in transmission and reflection geometry. A comprehensive analysis of the THz images revealed a contrast up to 23% between the neoplastic and control tissues. Absorption and reflection THz images demonstrated the possibility to distinguish adenocarcinoma-affected areas even without water in the tissue, as the main contrast mechanism in THz measurements has been observed to be water absorption in in vivo or freshly excised tissues. The present results corroborate with previous histologic findings in the same tissues, and confirm that the contrast prevails even in dehydrated tissues.

  14. Imaging-based logics for ornamental stone quality chart definition

    NASA Astrophysics Data System (ADS)

    Bonifazi, Giuseppe; Gargiulo, Aldo; Serranti, Silvia; Raspi, Costantino

    2007-02-01

    Ornamental stone products are commercially classified on the market according to several factors related both to intrinsic lythologic characteristics and to their visible pictorial attributes. Sometimes these latter aspects prevail in quality criteria definition and assessment. Pictorial attributes are in any case also influenced by the performed working actions and the utilized tools selected to realize the final stone manufactured product. Stone surface finishing is a critical task because it can contribute to enhance certain aesthetic features of the stone itself. The study was addressed to develop an innovative set of methodologies and techniques able to quantify the aesthetic quality level of stone products taking into account both the physical and the aesthetical characteristics of the stones. In particular, the degree of polishing of the stone surfaces and the presence of defects have been evaluated, applying digital image processing strategies. Morphological and color parameters have been extracted developing specific software architectures. Results showed as the proposed approaches allow to quantify the degree of polishing and to identify surface defects related to the intrinsic characteristics of the stone and/or the performed working actions.

  15. Crowdsourcing quality control for Dark Energy Survey images

    DOE PAGESBeta

    Melchior, P.

    2016-07-01

    We have developed a crowdsourcing web application for image quality controlemployed by the Dark Energy Survey. Dubbed the "DES exposure checker", itrenders science-grade images directly to a web browser and allows users to markproblematic features from a set of predefined classes. Users can also generatecustom labels and thus help identify previously unknown problem classes. Userreports are fed back to hardware and software experts to help mitigate andeliminate recognized issues. We report on the implementation of the applicationand our experience with its over 100 users, the majority of which areprofessional or prospective astronomers but not data management experts. Wediscuss aspects ofmore » user training and engagement, and demonstrate how problemreports have been pivotal to rapidly correct artifacts which would likely havebeen too subtle or infrequent to be recognized otherwise. We conclude with anumber of important lessons learned, suggest possible improvements, andrecommend this collective exploratory approach for future astronomical surveysor other extensive data sets with a sufficiently large user base. We alsorelease open-source code of the web application and host an online demo versionat http://des-exp-checker.pmelchior.net« less

  16. Crowdsourcing quality control for Dark Energy Survey images

    NASA Astrophysics Data System (ADS)

    Melchior, P.; Sheldon, E.; Drlica-Wagner, A.; Rykoff, E. S.; Abbott, T. M. C.; Abdalla, F. B.; Allam, S.; Benoit-Lévy, A.; Brooks, D.; Buckley-Geer, E.; Carnero Rosell, A.; Carrasco Kind, M.; Carretero, J.; Crocce, M.; D'Andrea, C. B.; da Costa, L. N.; Desai, S.; Doel, P.; Evrard, A. E.; Finley, D. A.; Flaugher, B.; Frieman, J.; Gaztanaga, E.; Gerdes, D. W.; Gruen, D.; Gruendl, R. A.; Honscheid, K.; James, D. J.; Jarvis, M.; Kuehn, K.; Li, T. S.; Maia, M. A. G.; March, M.; Marshall, J. L.; Nord, B.; Ogando, R.; Plazas, A. A.; Romer, A. K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Smith, R. C.; Soares-Santos, M.; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Vikram, V.; Walker, A. R.; Wester, W.; Zhang, Y.

    2016-07-01

    We have developed a crowdsourcing web application for image quality control employed by the Dark Energy Survey. Dubbed the "DES exposure checker", it renders science-grade images directly to a web browser and allows users to mark problematic features from a set of predefined classes. Users can also generate custom labels and thus help identify previously unknown problem classes. User reports are fed back to hardware and software experts to help mitigate and eliminate recognized issues. We report on the implementation of the application and our experience with its over 100 users, the majority of which are professional or prospective astronomers but not data management experts. We discuss aspects of user training and engagement, and demonstrate how problem reports have been pivotal to rapidly correct artifacts which would likely have been too subtle or infrequent to be recognized otherwise. We conclude with a number of important lessons learned, suggest possible improvements, and recommend this collective exploratory approach for future astronomical surveys or other extensive data sets with a sufficiently large user base. We also release open-source code of the web application and host an online demo version at http://des-exp-checker.pmelchior.net.

  17. Optimization of beam quality for photon-counting spectral computed tomography in head imaging: simulation study.

    PubMed

    Chen, Han; Xu, Cheng; Persson, Mats; Danielsson, Mats

    2015-10-01

    Head computed tomography (CT) plays an important role in the comprehensive evaluation of acute stroke. Photon-counting spectral detectors, as promising candidates for use in the next generation of x-ray CT systems, allow for assigning more weight to low-energy x-rays that generally contain more contrast information. Most importantly, the spectral information can be utilized to decompose the original set of energy-selective images into several basis function images that are inherently free of beam-hardening artifacts, a potential advantage for further improving the diagnosis accuracy. We are developing a photon-counting spectral detector for CT applications. The purpose of this work is to determine the optimal beam quality for material decomposition in two head imaging cases: nonenhanced imaging and K-edge imaging. A cylindrical brain tissue of 16-cm diameter, coated by a 6-mm-thick bone layer and 2-mm-thick skin layer, was used as a head phantom. The imaging target was a 5-mm-thick blood vessel centered in the head phantom. In K-edge imaging, two contrast agents, iodine and gadolinium, with the same concentration ([Formula: see text]) were studied. Three parameters that affect beam quality were evaluated: kVp settings (50 to 130 kVp), filter materials ([Formula: see text] to 83), and filter thicknesses [0 to 2 half-value layer (HVL)]. The image qualities resulting from the varying x-ray beams were compared in terms of two figures of merit (FOMs): squared signal-difference-to-noise ratio normalized by brain dose ([Formula: see text]) and that normalized by skin dose ([Formula: see text]). For nonenhanced imaging, the results show that the use of the 120-kVp spectrum filtered by 2 HVL copper ([Formula: see text]) provides the best performance in both FOMs. When iodine is used in K-edge imaging, the optimal filter is 2 HVL iodine ([Formula: see text]) and the optimal kVps are 60 kVp in terms of [Formula: see text] and 75 kVp in terms of [Formula: see text]. A

  18. No-reference image quality assessment based on nonsubsample shearlet transform and natural scene statistics

    NASA Astrophysics Data System (ADS)

    Wang, Guan-jun; Wu, Zhi-yong; Yun, Hai-jiao; Cui, Ming

    2016-03-01

    A novel no-reference (NR) image quality assessment (IQA) method is proposed for assessing image quality across multifarious distortion categories. The new method transforms distorted images into the shearlet domain using a non-subsample shearlet transform (NSST), and designs the image quality feature vector to describe images utilizing natural scenes statistical features: coefficient distribution, energy distribution and structural correlation ( SC) across orientations and scales. The final image quality is achieved from distortion classification and regression models trained by a support vector machine (SVM). The experimental results on the LIVE2 IQA database indicate that the method can assess image quality effectively, and the extracted features are susceptive to the category and severity of distortion. Furthermore, our proposed method is database independent and has a higher correlation rate and lower root mean squared error ( RMSE) with human perception than other high performance NR IQA methods.

  19. Neuron Image Analyzer: Automated and Accurate Extraction of Neuronal Data from Low Quality Images.

    PubMed

    Kim, Kwang-Min; Son, Kilho; Palmore, G Tayhas R

    2015-01-01

    Image analysis software is an essential tool used in neuroscience and neural engineering to evaluate changes in neuronal structure following extracellular stimuli. Both manual and automated methods in current use are severely inadequate at detecting and quantifying changes in neuronal morphology when the images analyzed have a low signal-to-noise ratio (SNR). This inadequacy derives from the fact that these methods often include data from non-neuronal structures or artifacts by simply tracing pixels with high intensity. In this paper, we describe Neuron Image Analyzer (NIA), a novel algorithm that overcomes these inadequacies by employing Laplacian of Gaussian filter and graphical models (i.e., Hidden Markov Model, Fully Connected Chain Model) to specifically extract relational pixel information corresponding to neuronal structures (i.e., soma, neurite). As such, NIA that is based on vector representation is less likely to detect false signals (i.e., non-neuronal structures) or generate artifact signals (i.e., deformation of original structures) than current image analysis algorithms that are based on raster representation. We demonstrate that NIA enables precise quantification of neuronal processes (e.g., length and orientation of neurites) in low quality images with a significant increase in the accuracy of detecting neuronal changes post-stimulation. PMID:26593337

  20. Neuron Image Analyzer: Automated and Accurate Extraction of Neuronal Data from Low Quality Images

    PubMed Central

    Kim, Kwang-Min; Son, Kilho; Palmore, G. Tayhas R.

    2015-01-01

    Image analysis software is an essential tool used in neuroscience and neural engineering to evaluate changes in neuronal structure following extracellular stimuli. Both manual and automated methods in current use are severely inadequate at detecting and quantifying changes in neuronal morphology when the images analyzed have a low signal-to-noise ratio (SNR). This inadequacy derives from the fact that these methods often include data from non-neuronal structures or artifacts by simply tracing pixels with high intensity. In this paper, we describe Neuron Image Analyzer (NIA), a novel algorithm that overcomes these inadequacies by employing Laplacian of Gaussian filter and graphical models (i.e., Hidden Markov Model, Fully Connected Chain Model) to specifically extract relational pixel information corresponding to neuronal structures (i.e., soma, neurite). As such, NIA that is based on vector representation is less likely to detect false signals (i.e., non-neuronal structures) or generate artifact signals (i.e., deformation of original structures) than current image analysis algorithms that are based on raster representation. We demonstrate that NIA enables precise quantification of neuronal processes (e.g., length and orientation of neurites) in low quality images with a significant increase in the accuracy of detecting neuronal changes post-stimulation. PMID:26593337

  1. Laying performance and egg quality of blue-shelled layers as affected by different housing systems.

    PubMed

    Wang, X L; Zheng, J X; Ning, Z H; Qu, L J; Xu, G Y; Yang, N

    2009-07-01

    Blue-shelled eggs are gaining popularity as the consumption demand diversifies in some countries. This study was carried out to investigate the laying performance and egg quality of the blue-shelled egg layers as well as the effects of different housing systems on egg production and quality traits. One thousand pullets from Dongxiang blue-shelled layers were divided into 2 even groups and kept in different housing systems (outdoor vs. cage). Daily laying performance was recorded from 20 to 60 wk of age. External and internal egg quality traits were examined at 26, 34, 42, and 50 wk. Yolk cholesterol concentration and whole egg cholesterol content were measured at 40 wk of age. Average laying rate from 20 to 60 wk for the cage (54.7%) was significantly higher than that of outdoor layers (39.3%). Among all of the egg quality traits, only eggshell color was affected by housing system. Interaction between housing system and layer age was found in egg weight, eggshell color, eggshell ratio, yolk color, and yolk weight. Meanwhile, cholesterol concentration in yolk was 8.64 +/- 0.40 mg/g in the outdoor eggs, which was significantly lower than that of eggs from the cage birds (10.32 +/- 0.48 mg/g; P < 0.05). Whole egg cholesterol content in the outdoor eggs (125.23 +/- 6.32 mg/egg) was also significantly lower than that of eggs from the caged layers (158.01 +/- 8.62 mg/egg). The results demonstrated that blue-shelled layers have lower productivity in the outdoor system than in the cage system. Blue-shelled layers have lower egg weight, larger yolk proportion, and lower cholesterol content compared with commercial layers. In a proper marketing system, lower productivity could be balanced by a higher price for the better quality of blue-shelled eggs. PMID:19531721

  2. Factors Affecting Source-Water Quality after Disturbance of Forests by Wildfire

    NASA Astrophysics Data System (ADS)

    Murphy, S. F.; Martin, D. A.; McCleskey, R. B.; Writer, J. H.

    2015-12-01

    Forests yield high-quality water supplies to communities throughout the world, in part because forest cover reduces flooding and the consequent transport of suspended and dissolved constituents to surface water. Disturbance by wildfire reduces or eliminates forest cover, leaving watersheds susceptible to increased surface runoff during storms and reduced ability to retain contaminants. We assessed water-quality response to hydrologic events for three years after a wildfire in the Fourmile Creek Watershed, near Boulder, Colorado, and found that hydrologic and geochemical responses downstream of a burned area were primarily driven by small, brief convective storms that had relatively high, but not unusual, rainfall intensity. Total suspended sediment, dissolved organic carbon, nitrate, and manganese concentrations were 10-156 times higher downstream of a burned area compared to upstream, and water quality was sufficiently impaired to pose water-treatment concerns. The response in both concentration and yield of water-quality constituents differed depending on source availability and dominant watershed processes controlling the constituent. For example, while all constituent concentrations were highest during storm events, annual sediment yields downstream of the burned area were controlled by storm events and subsequent mobilization, whereas dissolved organic carbon yields were more dependent on spring runoff from upstream areas. The watershed response was affected by a legacy of historical disturbance: the watershed had been recovering from extensive disturbance by mining, railroad and road development, logging, and fires in the late 19th and early 20th centuries, and we observed extensive erosion of mine waste in response to these summer storms. Therefore, both storm characteristics and historical disturbance in a burned watershed must be considered when evaluating the role of wildfire on water quality.

  3. Factors affecting the quality of anticoagulation with warfarin: experience of one cardiac centre

    PubMed Central

    Ciurus, Tomasz; Cichocka-Radwan, Anna

    2015-01-01

    Introduction The risk of complications in anticoagulation therapy can be reduced by maximising the percentage of time spent by the patient in the optimal therapeutic range (TTR). However, little is known about the predictors of anticoagulation control. The aim of this paper was to assess the quality of anticoagulant therapy in patients on warfarin and to identify the factors affecting its deterioration. Material and methods We studied 149 patients who required anticoagulant therapy with warfarin due to non-valvular atrial fibrillation and/or venous thromboembolism. Each patient underwent proper training regarding the implemented treatment and remained under constant medical care. Results The mean age of the patients was 68.8 ± 12.6 years, and 59% were male. A total of 2460 international normalised ratio (INR) measurements were collected during the 18-month period. The mean TTR in the studied cohort was 76 ± 21%, and the median was 80%. The level at which high-quality anticoagulation was recorded for this study was based on TTR values above 80%. Seventy-five patients with TTR ≥ 80% were included in the stable anticoagulation group (TTR ≥ 80%); the remaining 74 patients constituted the unstable anticoagulation group (TTR < 80%). According to multivariate stepwise regression analysis, the independent variables increasing the risk of deterioration of anticoagulation quality were: arterial hypertension (OR 2.74 [CI 95%: 1.06-7.10]; p = 0.038), amiodarone therapy (OR 4.22 [CI 95%: 1.30-13.70]; p = 0.017), and obesity (OR 1.11 [CI 95%: 1.02-1.21]; p = 0.013). Conclusions The presence of obesity, hypertension, or amiodarone therapy decreases the quality of anticoagulation with warfarin. High quality of anticoagulation can be achieved through proper monitoring and education of patients. PMID:26855650

  4. Development of Software to Model AXAF-I Image Quality

    NASA Technical Reports Server (NTRS)

    Ahmad, Anees; Hawkins, Lamar

    1996-01-01

    This draft final report describes the work performed under the delivery order number 145 from May 1995 through August 1996. The scope of work included a number of software development tasks for the performance modeling of AXAF-I. A number of new capabilities and functions have been added to the GT software, which is the command mode version of the GRAZTRACE software, originally developed by MSFC. A structural data interface has been developed for the EAL (old SPAR) finite element analysis FEA program, which is being used by MSFC Structural Analysis group for the analysis of AXAF-I. This interface utility can read the structural deformation file from the EAL and other finite element analysis programs such as NASTRAN and COSMOS/M, and convert the data to a suitable format that can be used for the deformation ray-tracing to predict the image quality for a distorted mirror. There is a provision in this utility to expand the data from finite element models assuming 180 degrees symmetry. This utility has been used to predict image characteristics for the AXAF-I HRMA, when subjected to gravity effects in the horizontal x-ray ground test configuration. The development of the metrology data processing interface software has also been completed. It can read the HDOS FITS format surface map files, manipulate and filter the metrology data, and produce a deformation file, which can be used by GT for ray tracing for the mirror surface figure errors. This utility has been used to determine the optimum alignment (axial spacing and clocking) for the four pairs of AXAF-I mirrors. Based on this optimized alignment, the geometric images and effective focal lengths for the as built mirrors were predicted to cross check the results obtained by Kodak.

  5. Optoacoustic imaging quality enhancement based on geometrical super-resolution method

    NASA Astrophysics Data System (ADS)

    He, Hailong; Mandal, Subhamoy; Buehler, Andreas; Deán-Ben, X. Luís.; Razansky, Daniel; Ntziachristos, Vasilis

    2016-03-01

    In optoacoustic imaging, the resolution and image quality in a certain imaging position usually cannot be enhanced without changing the imaging configuration. Post-reconstruction image processing methods offer a new possibility to improve image quality and resolution. We have developed a geometrical super-resolution (GSR) method which uses information from spatially separated frames to enhance resolution and contrast in optoacoustic images. The proposed method acquires several low resolution images from the same object located at different positions inside the imaging plane. Thereafter, it applies an iterative registration algorithm to integrate the information in the acquired set of images to generate a single high resolution image. Herein, we present the method and evaluate its performance in simulation and phantom experiments, and results show that geometrical super-resolution techniques can be a promising alternative to enhance resolution in optoacoustic imaging.

  6. Exposure of wood in floodplains affects its chemical quality and its subsequent breakdown in streams.

    PubMed

    del Campo, Rubén; Gómez, Rosa

    2016-02-01

    In stream ecosystems, coarse organic matter from the riparian vegetation, a key food resource, is often retained in the floodplains before reaching the channel. During floodplain exposure, organic matter can be affected by abiotic and biotic processes ("preconditioning"), which alter its quality and affect its subsequent decomposition in streams. We analyzed the effect of floodplain preconditioning on wood quality (lignin, C, N, P, K, among others), and its subsequent aquatic breakdown, paying special attention to microbial activity. We simulated preconditioned standard wooden sticks on one arid stream floodplain for 3 and 4 months, and then monitored their breakdown in three different streams, together with control (non-preconditioned) sticks. Preconditioning reduced lignin mass and C:N and lignin:N ratios, caused the leaching of soluble nutrients such as P and K, as well as N immobilization by microbes. These changes enhanced the breakdown of wood in the first week of immersion, but had no effect on breakdown rates after 4 months of incubation in the streams, although N immobilization was diminished. Our results suggest that terrestrial preconditioning could alter the role of wood as a long-lasting nutrients and energy source for freshwater ecosystem. PMID:26613519

  7. Sociodemographic factors affecting the quality of life of patients with asthma

    PubMed Central

    Uchmanowicz, Bartosz; Panaszek, Bernard; Uchmanowicz, Izabella; Rosińczuk, Joanna

    2016-01-01

    Background In recent years, there has been an increased interest in the subjective quality of life (QoL) of patients with bronchial asthma. Patients diagnosed with asthma experience a number of problems with regard to everyday activities and functions, which adversely affects their health-related QoL. Aim The aim of this study is to analyze the sociodemographic factors affecting the QoL of patients with asthma. Patients and methods The study comprised of 100 patients (73 females and 27 males) aged 18–84 years (mean age 45.7 years) treated in the Department and Clinic of Internal Diseases, Geriatrics and Allergology, Wroclaw Medical University. All patients with asthma who met the inclusion criteria participated in the study. We used medical record analysis and two questionnaires: the asthma quality of life questionnaire (AQLQ) and the asthma control test. Up-to-date sociodemographic data were collected from all participants, including sex, age, marital status, education, and sources of income. Results The sociodemographic variables that correlated positively with QoL in all domains of the AQLQ were professional activity and higher education level of respondents. Factors that negatively influenced the AQLQ domains were older age and lack of professional activity. Conclusion This study shows that age, physical work, and lack of professional activity decreased the QoL in this patient group. It was found that higher education contributes to better QoL scores. PMID:27051276

  8. Risk factors affecting chemical and bacteriological quality of bulk tank milk in Kerman, Iran

    PubMed Central

    Mansouri-Najand, Ladan; Rezaii, Zeinab

    2015-01-01

    Milk is often described as a complete food because it contains protein, sugar, fat, vitamins, and minerals. This study was performed to investigate risk factors affecting chemical and bacteriological quality of bulk tank milk. According to the following conducted experiments, the milk was divided into two standard and non-standard groups. Then, effect of risk factors on making the samples non-standard was studied. Risk factors such as type of milk delivery unit, distance of cattle farm from plant, size of herd, education level of stockbreeders, capacity of milk transport tank, capacity of cooler device, and number of workers employed in cattle farms were evaluated in this study. Microbial and chemical evaluations were performed. Beta-lactam antibiotic residues and somatic cell count were specified. At the same time, the stockbreeders who referred to the plant were given some questionnaires and the mentioned primary questions were asked. After collecting the data, logistic regression model was used. According to the obtained results and comparison with Iran’s national standard, 26 out of 109 samples were determined to be at standard level and 83 ones had at least one out-of-standard factor. The results obtained from the model demonstrated significant effect of education of stockbreeders and capacity of cooler devices on the milk quality. Education of stockbreeders could greatly affect management of a cattle farm unit. PMID:25992256

  9. Quality Imaging - Comparison of CR Mammography with Screen-Film Mammography

    SciTech Connect

    Gaona, E.; Azorin Nieto, J.; Iran Diaz Gongora, J. A.; Arreola, M.; Casian Castellanos, G.; Perdigon Castaneda, G. M.; Franco Enriquez, J. G.

    2006-09-08

    The aim of this work is a quality imaging comparison of CR mammography images printed to film by a laser printer with screen-film mammography. A Giotto and Elscintec dedicated mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in screen-film mammography. Four CR mammography units from two different manufacturers and three dedicated x-ray mammography units with fully automatic exposure and a nominal large focal spot size of 0.3 mm were used for the image acquisition of phantoms in CR mammography. The tests quality image included an assessment of system resolution, scoring phantom images, Artifacts, mean optical density and density difference (contrast). In this study, screen-film mammography with a quality control program offers a significantly greater level of quality image relative to CR mammography images printed on film.

  10. Improved image quality for x-ray CT imaging of gel dosimeters

    SciTech Connect

    Kakakhel, M. B.; Kairn, T.; Kenny, J.; Trapp, J. V.

    2011-09-15

    Purpose: This study provides a simple method for improving precision of x-ray computed tomography (CT) scans of irradiated polymer gel dosimetry. The noise affecting CT scans of irradiated gels has been an impediment to the use of clinical CT scanners for gel dosimetry studies. Methods: In this study, it is shown that multiple scans of a single PAGAT gel dosimeter can be used to extrapolate a ''zero-scan'' image which displays a similar level of precision to an image obtained by averaging multiple CT images, without the compromised dose measurement resulting from the exposure of the gel to radiation from the CT scanner. Results: When extrapolating the zero-scan image, it is shown that exponential and simple linear fits to the relationship between Hounsfield unit and scan number, for each pixel in the image, provide an accurate indication of gel density. Conclusions: It is expected that this work will be utilized in the analysis of three-dimensional gel volumes irradiated using complex radiotherapy treatments.

  11. Do Stereotypic Images in Video Games Affect Attitudes and Behavior? Adolescents’ Perspectives

    PubMed Central

    Henning, Alexandra; Brenick, Alaina; Killen, Melanie; O’Connor, Alexander; Collins, Michael J.

    2015-01-01

    This study examined adolescents’ attitudes about video games along with their self-reported play frequency. Ninth and eleventh grade students (N = 361), approximately evenly divided by grade and gender, were surveyed about whether video games have stereotypic images, involve harmful consequences or affect one’s attitudes, whether game playing should be regulated by parents or the government, and whether game playing is a personal choice. Adolescents who played video games frequently showed decreased concern about the effects that games with negatively stereotyped images may have on the players’ attitudes compared to adolescents who played games infrequently or not at all. With age, adolescents were more likely to view images as negative, but were also less likely to recognize stereotypic images of females as harmful and more likely to judge video-game playing as a personal choice. The paper discusses other findings in relation to research on adolescents’ social cognitive judgments. PMID:25729336

  12. Full-reference quality estimation for images with different spatial resolutions.

    PubMed

    Demirtas, Ali Murat; Reibman, Amy R; Jafarkhani, Hamid

    2014-05-01

    Multimedia communication is becoming pervasive because of the progress in wireless communications and multimedia coding. Estimating the quality of the visual content accurately is crucial in providing satisfactory service. State of the art visual quality assessment approaches are effective when the input image and reference image have the same resolution. However, finding the quality of an image that has spatial resolution different than that of the reference image is still a challenging problem. To solve this problem, we develop a quality estimator (QE), which computes the quality of the input image without resampling the reference or the input images. In this paper, we begin by identifying the potential weaknesses of previous approaches used to estimate the quality of experience. Next, we design a QE to estimate the quality of a distorted image with a lower resolution compared with the reference image. We also propose a subjective test environment to explore the success of the proposed algorithm in comparison with other QEs. When the input and test images have different resolutions, the subjective tests demonstrate that in most cases the proposed method works better than other approaches. In addition, the proposed algorithm also performs well when the reference image and the test image have the same resolution. PMID:24686279

  13. Application of ultrasound processed images in space: Quanitative assessment of diffuse affectations

    NASA Astrophysics Data System (ADS)

    Pérez-Poch, A.; Bru, C.; Nicolau, C.

    The purpose of this study was to evaluate diffuse affectations in the liver using texture image processing techniques. Ultrasound diagnose equipments are the election of choice to be used in space environments as they are free from hazardous effects on health. However, due to the need for highly trained radiologists to assess the images, this imaging method is mainly applied on focal lesions rather than on non-focal ones. We have conducted a clinical study on 72 patients with different degrees of chronic hepatopaties and a group of control of 18 individuals. All subjects' clinical reports and results of biopsies were compared to the degree of affectation calculated by our computer system , thus validating the method. Full statistical results are given in the present paper showing a good correlation (r=0.61) between pathologist's report and analysis of the heterogenicity of the processed images from the liver. This computer system to analyze diffuse affectations may be used in-situ or via telemedicine to the ground.

  14. On the Difference between Seeing and Image Quality: When the Turbulence Outer Scale Enters the Game

    NASA Astrophysics Data System (ADS)

    Martinez, P.; Kolb, J.; Sarazin, M.; Tokovinin, A.

    2010-09-01

    We attempt to clarify the frequent confusion between seeing and image quality for large telescopes. The full width at half maximum of a stellar image is commonly considered to be equal to the atmospheric seeing. However the outer scale of the turbulence, which corresponds to a reduction in the low frequency content of the phase perturbation spectrum, plays a significant role in the improvement of image quality at the focus of a telescope. The image quality is therefore different (and in some cases by a large factor) from the atmospheric seeing that can be measured by dedicated seeing monitors, such as a differential image motion monitor.

  15. National Beef Quality Audit-2011: Harvest-floor assessments of targeted characteristics that affect quality and value of cattle, carcasses, and byproducts

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The National Beef Quality Audit-2011(NBQA-2011) was conducted to assess targeted characteristics on the harvest floor that affect the quality and value of cattle, carcasses, and byproducts. Survey teams evaluated approximately 18,000 cattle/carcasses between May and November 2011 in 8 beef processin...

  16. Water quality and processes affecting dissolved oxygen concentrations in the Blackwater River, Canaan Valley, West Virginia

    USGS Publications Warehouse

    Waldron, M.C.; Wiley, J.B.

    1996-01-01

    The water quality and environmental processes affecting dissolved oxygen were determined for the Blackwater River in Canaan Valley, West Virginia. Canaan Valley is oval-shaped (14 miles by 5 miles) and is located in the Allegheny Mountains at an average elevation of 3,200 feet above sea level. Tourism, population, and real estate development have increased in the past two decades. Most streams in Canaan Valley are a dilute calcium magnesium bicarbonate-type water. Streamwater typicaly was soft and low in alkalinity and dissolved solids. Maximum values for specific conductance, hardness, alkalinity, and dissolved solids occurred during low-flow periods when streamflow was at or near baseflow. Dissolved oxygen concentrations are most sensitive to processes affecting the rate of reaeration. The reaeration is affected by solubility (atmospheric pressure, water temperature, humidity, and cloud cover) and processes that determine stream turbulence (stream depth, width, velocity, and roughness). In the headwaters, photosynthetic dissolved oxygen production by benthic algae can result in supersaturated dissolved oxygen concentrations. In beaver pools, dissolved oxygen consumption from sediment oxygen demand and carbonaceous biochemical oxygen demand can result in dissolved oxygen deficits.

  17. How variation in head pitch could affect image matching algorithms for ant navigation.

    PubMed

    Ardin, Paul; Mangan, Michael; Wystrach, Antoine; Webb, Barbara

    2015-06-01

    Desert ants are a model system for animal navigation, using visual memory to follow long routes across both sparse and cluttered environments. Most accounts of this behaviour assume retinotopic image matching, e.g. recovering heading direction by finding a minimum in the image difference function as the viewpoint rotates. But most models neglect the potential image distortion that could result from unstable head motion. We report that for ants running across a short section of natural substrate, the head pitch varies substantially: by over 20 degrees with no load; and 60 degrees when carrying a large food item. There is no evidence of head stabilisation. Using a realistic simulation of the ant's visual world, we demonstrate that this range of head pitch significantly degrades image matching. The effect of pitch variation can be ameliorated by a memory bank of densely sampled along a route so that an image sufficiently similar in pitch and location is available for comparison. However, with large pitch disturbance, inappropriate memories sampled at distant locations are often recalled and navigation along a route can be adversely affected. Ignoring images obtained at extreme pitches, or averaging images over several pitches, does not significantly improve performance. PMID:25895895

  18. A comparison of Image Quality Models and Metrics Predicting Object Detection

    NASA Technical Reports Server (NTRS)

    Rohaly, Ann Marie; Ahumada, Albert J., Jr.; Watson, Andrew B.; Null, Cynthia H. (Technical Monitor)

    1995-01-01

    Many models and metrics for image quality predict image discriminability, the visibility of the difference between a pair of images. Some image quality applications, such as the quality of imaging radar displays, are concerned with object detection and recognition. Object detection involves looking for one of a large set of object sub-images in a large set of background images and has been approached from this general point of view. We find that discrimination models and metrics can predict the relative detectability of objects in different images, suggesting that these simpler models may be useful in some object detection and recognition applications. Here we compare three alternative measures of image discrimination, a multiple frequency channel model, a single filter model, and RMS error.

  19. Quantitative and qualitative image quality analysis of super resolution images from a low cost scanning laser ophthalmoscope

    NASA Astrophysics Data System (ADS)

    Murillo, Sergio; Echegaray, Sebastian; Zamora, Gilberto; Soliz, Peter; Bauman, Wendall

    2011-03-01

    The lurking epidemic of eye diseases caused by diabetes and aging will put more than 130 million Americans at risk of blindness by 2020. Screening has been touted as a means to prevent blindness by identifying those individuals at risk. However, the cost of most of today's commercial retinal imaging devices makes their use economically impractical for mass screening. Thus, low cost devices are needed. With these devices, low cost often comes at the expense of image quality with high levels of noise and distortion hindering the clinical evaluation of those retinas. A software-based super resolution (SR) reconstruction methodology that produces images with improved resolution and quality from multiple low resolution (LR) observations is introduced. The LR images are taken with a low-cost Scanning Laser Ophthalmoscope (SLO). The non-redundant information of these LR images is combined to produce a single image in an implementation that also removes noise and imaging distortions while preserving fine blood vessels and small lesions. The feasibility of using the resulting SR images for screening of eye diseases was tested using quantitative and qualitative assessments. Qualitatively, expert image readers evaluated their ability of detecting clinically significant features on the SR images and compared their findings with those obtained from matching images of the same eyes taken with commercially available high-end cameras. Quantitatively, measures of image quality were calculated from SR images and compared to subject-matched images from a commercial fundus imager. Our results show that the SR images have indeed enough quality and spatial detail for screening purposes.

  20. Mapping gully-affected areas in the region of Taroudannt, Morocco based on Object-Based Image Analysis (OBIA)

    NASA Astrophysics Data System (ADS)

    d'Oleire-Oltmanns, Sebastian; Marzolff, Irene; Tiede, Dirk; Blaschke, Thomas

    2015-04-01

    The need for area-wide landform mapping approaches, especially in terms of land degradation, can be ascribed to the fact that within area-wide landform mapping approaches, the (spatial) context of erosional landforms is considered by providing additional information on the physiography neighboring the distinct landform. This study presents an approach for the detection of gully-affected areas by applying object-based image analysis in the region of Taroudannt, Morocco, which is highly affected by gully erosion while simultaneously representing a major region of agro-industry with a high demand of arable land. Various sensors provide readily available high-resolution optical satellite data with a much better temporal resolution than 3D terrain data which lead to the development of an area-wide mapping approach to extract gully-affected areas using only optical satellite imagery. The classification rule-set was developed with a clear focus on virtual spatial independence within the software environment of eCognition Developer. This allows the incorporation of knowledge about the target objects under investigation. Only optical QuickBird-2 satellite data and freely-available OpenStreetMap (OSM) vector data were used as input data. The OSM vector data were incorporated in order to mask out plantations and residential areas. Optical input data are more readily available for a broad range of users compared to terrain data, which is considered to be a major advantage. The methodology additionally incorporates expert knowledge and freely-available vector data in a cyclic object-based image analysis approach. This connects the two fields of geomorphology and remote sensing. The classification results allow conclusions on the current distribution of gullies. The results of the classification were checked against manually delineated reference data incorporating expert knowledge based on several field campaigns in the area, resulting in an overall classification accuracy of 62

  1. A Multivariate Model for Coastal Water Quality Mapping Using Satellite Remote Sensing Images

    PubMed Central

    Su, Yuan-Fong; Liou, Jun-Jih; Hou, Ju-Chen; Hung, Wei-Chun; Hsu, Shu-Mei; Lien, Yi-Ting; Su, Ming-Daw; Cheng, Ke-Sheng; Wang, Yeng-Fung

    2008-01-01

    This study demonstrates the feasibility of coastal water quality mapping using satellite remote sensing images. Water quality sampling campaigns were conducted over a coastal area in northern Taiwan for measurements of three water quality variables including Secchi disk depth, turbidity, and total suspended solids. SPOT satellite images nearly concurrent with the water quality sampling campaigns were also acquired. A spectral reflectance estimation scheme proposed in this study was applied to SPOT multispectral images for estimation of the sea surface reflectance. Two models, univariate and multivariate, for water quality estimation using the sea surface reflectance derived from SPOT images were established. The multivariate model takes into consideration the wavelength-dependent combined effect of individual seawater constituents on the sea surface reflectance and is superior over the univariate model. Finally, quantitative coastal water quality mapping was accomplished by substituting the pixel-specific spectral reflectance into the multivariate water quality estimation model.

  2. Sentinel-2 radiometric image quality commissioning: first results

    NASA Astrophysics Data System (ADS)

    Lachérade, S.; Lonjou, V.; Farges, M.; Gamet, P.; Marcq, S.; Raynaud, J.-L.; Trémas, T.

    2015-10-01

    In partnership with the European Commission and in the frame of the Copernicus program, the European Space Agency (ESA) is developing the Sentinel-2 optical imaging mission devoted to the operational monitoring of land and coastal areas. The Sentinel-2 mission is based on a satellites constellation deployed in polar sun-synchronous orbit. Sentinel-2 offers a unique combination of global coverage with a wide field of view (290km), a high revisit (5 days with two satellites), a high spatial resolution (10m, 20m and 60m) and multi-spectral imagery (13 spectral bands in visible and shortwave infrared domains). The first satellite, Sentinel-2A, has been launched in June 2015. The Sentinel-2A Commissioning Phase starts immediately after the Launch and Early Orbit Phase and continues until the In-Orbit Commissioning Review which is planned three months after the launch. The Centre National d'Etudes Spatiales (CNES) supports ESA/ESTEC to insure the Calibration/Validation commissioning phase during the first three months in flight. This paper provides first an overview of the Sentinel-2 system and a description of the products delivered by the ground segment associated to the main radiometric specifications to achieve. Then the paper focuses on the preliminary radiometric results obtained during the in-flight commissioning phase. The radiometric methods and calibration sites used in the CNES image quality center to reach the specifications of the sensor are described. A status of the Sentinel-2A radiometric performances at the end of the first three months after the launch is presented. We will particularly address in this paper the results in term of absolute calibration, pixel to pixel relative sensitivity and MTF estimation.

  3. The Osteoarthritis Initiative (OAI) magnetic resonance imaging quality assurance update

    PubMed Central

    Schneider, E.; NessAiver, M.

    2012-01-01

    Objective Longitudinal quantitative evaluation of cartilage disease requires reproducible measurements over time. We report 8 years of quality assurance (QA) metrics for quantitative magnetic resonance (MR) knee analyses from the Osteoarthritis Initiative (OAI) and show the impact of MR system, phantom, and acquisition protocol changes. Method Key 3 T MR QA metrics, including signal-to-noise, signal uniformity, T2 relaxation times, and geometric distortion, were quantified monthly on two different phantoms using an automated program. Results Over 8 years, phantom measurements showed root-mean-square coefficient-of-variation reproducibility of <0.25% (190.0 mm diameter) and <0.20% (148.0 mm length), resulting in spherical volume reproducibility of <0.35%. T2 relaxation time reproducibility varied from 1.5% to 5.3%; seasonal fluctuations were observed at two sites. All other QA goals were met except: slice thicknesses were consistently larger than nominal on turbo spin echo images; knee coil signal uniformity and signal level varied significantly over time. Conclusions The longitudinal variations for a spherical volume should have minimal impact on the accuracy and reproducibility of cartilage volume and thickness measurements as they are an order of magnitude smaller than reported for either unpaired or paired (repositioning and reanalysis) precision errors. This stability should enable direct comparison of baseline and follow-up images. Cross-comparison of the geometric results from all four OAI sites reveal that the MR systems do not statistically differ and enable results to be pooled. MR QA results identified similar technical issues as previously published. Geometric accuracy stability should have the greatest impact on quantitative analysis of longitudinal change in cartilage volume and thickness precision. PMID:23092792

  4. Suture locking of isolated internal locking knotless suture anchors is not affected by bone quality

    PubMed Central

    Woodmass, Jarret M; Matthewson, Graeme; Ono, Yohei; Bois, Aaron J; Boorman, Richard S; Lo, Ian KY; Thornton, Gail M

    2015-01-01

    Purpose The purpose of this study was to evaluate the mechanical performance of different suture locking mechanisms including: i) interference fit between the anchor and the bone (eg, 4.5 mm PushLock, 5.5 mm SwiveLock), ii) internal locking mechanism within the anchor itself (eg, 5.5 mm SpeedScrew), or iii) a combination of interference fit and internal locking (eg, 4.5 mm MultiFIX P, 5.5 mm MultiFIX S). Methods Anchors were tested in foam blocks representing normal (20/8 foam) or osteopenic (8/8 foam) bone, using standard suture loops pulled in-line with the anchor to isolate suture locking. Mechanical testing included cyclic testing for 500 cycles from 10 N to 60 N at 60 mm/min, followed by failure testing at 60 mm/min. Displacement after 500 cycles at 60 N, number of cycles at 3 mm displacement, load at 3 mm displacement, and maximum load were evaluated. Results Comparing 8/8 foam to 20/8 foam, load at 3 mm displacement and maximum load were significantly decreased (P<0.05) with decreased bone quality for anchors that, even in part, relied on an interference fit suture locking mechanism (ie, 4.5 mm PushLock, 5.5 mm SwiveLock, 4.5 mm MultiFIX P, 5.5 mm MultiFIX S). Bone quality did not affect the mechanical performance of 5.5 mm SpeedScrew anchors which have an isolated internal locking mechanism. Conclusion The mechanical performance of anchors that relied, even in part, on interference fit were affected by bone quality. Isolated internal locking knotless suture anchors functioned independently of bone quality. Anchors with a combined type (interference fit and internal locking) suture locking mechanism demonstrated similar mechanical performance to isolated internal locking anchors in osteopenic foam comparing similar sized anchors. Clinical relevance In osteopenic bone, knotless suture anchors that have an internal locking mechanism (isolated or combined type) may be advantageous for secure tendon fixation to bone. PMID:26124683

  5. Spectral CT Imaging of Laryngeal and Hypopharyngeal Squamous Cell Carcinoma: Evaluation of Image Quality and Status of Lymph Nodes

    PubMed Central

    Li, Wei; Wang, Zhongzhou; Pang, Tao; Li, Jun; Shi, Hao; Zhang, Chengqi

    2013-01-01

    Purpose The purpose of this study was to evaluate image quality and status of lymph nodes in laryngeal and hypopharyngeal squamous cell carcinoma (SCC) patients using spectral CT imaging. Materials and Methods Thirty-eight patients with laryngeal and hypopharyngeal SCCs were scanned with spectral CT mode in venous phase. The conventional 140-kVp polychromatic images and one hundred and one sets of monochromatic images were generated ranging from 40 keV to 140 keV. The mean optimal keV was calculated on the monochromatic images. The image quality of the mean optimal keV monochromatic images and polychromatic images was compared with two different methods including a quantitative analysis method and a qualitative analysis method. The HU curve slope (λHU) in the target lymph nodes and the primary lesion was calculated respectively. The ratio of λHU was studied between metastatic and non-metastatic lymph nodes group. Results A total of 38 primary lesions were included. The mean optimal keV was obtained at 55±1.77 keV on the monochromatic images. The image quality evaluated by two different methods including a quantitative analysis method and a qualitative analysis method was obviously increased on monochromatic images than polychromatic images (p<0.05). The ratio of λHU between metastatic and non-metastatic lymph nodes was significantly different in the venous phase images (p<0.05). Conclusion The monochromatic images obtained with spectral CT can be used to improve the image quality of laryngeal and hypopharyngeal SCC and the N-staging accuracy. The quantitative ratio of λHU may be helpful for differentiating between metastatic and non-metastatic cervical lymph nodes. PMID:24386214

  6. Dysautonomia Differentially Influences the Effect of Affective Pain Perception on Quality of Life in Parkinson's Disease Patients

    PubMed Central

    Rada, D.; Seco, J.; Tijero, B.; Abecia, L. C.; Gómez-Esteban, J. C.

    2016-01-01

    Background. Our aim was to evaluate the real effect of dysautonomic symptoms on the influence of affective pain perception on quality of life in PD patients. Methods. An observational cross-sectional study was carried out using 105 Parkinson's disease (PD) patients of the Movement Disorders Unit, Hospital de Cruces (Bilbao, Spain) [men 59 (56.2%), women 46 (43.85%)]. Statistical analysis was made in order to evaluate the possible association of pain with life quality. Results. Quality of life measured by PDQ-39 (Parkinson's Disease Questionnaire for quality of life) was statistically associated with affective dimension of pain (PRIA, affective pain rating index). However, the influence of this dimension on PDQ-39 was different in the specific case of PD patients that experimented a high score (>12) in SCOPA-AUT (Scale for Outcomes in PD-Autonomic scale). Conclusions. These results confirm the effect of affective perception of pain in life quality of PD patients, indicating the critical role of autonomic symptoms in the modulation of the influence of pain on quality of life and showing the possible utility of dysautonomia as clinical prognostic indicator of quality of life in PD patients affected by pain. PMID:27239367

  7. Dysautonomia Differentially Influences the Effect of Affective Pain Perception on Quality of Life in Parkinson's Disease Patients.

    PubMed

    Rada, D; Seco, J; Echevarría, E; Tijero, B; Abecia, L C; Gómez-Esteban, J C

    2016-01-01

    Background. Our aim was to evaluate the real effect of dysautonomic symptoms on the influence of affective pain perception on quality of life in PD patients. Methods. An observational cross-sectional study was carried out using 105 Parkinson's disease (PD) patients of the Movement Disorders Unit, Hospital de Cruces (Bilbao, Spain) [men 59 (56.2%), women 46 (43.85%)]. Statistical analysis was made in order to evaluate the possible association of pain with life quality. Results. Quality of life measured by PDQ-39 (Parkinson's Disease Questionnaire for quality of life) was statistically associated with affective dimension of pain (PRIA, affective pain rating index). However, the influence of this dimension on PDQ-39 was different in the specific case of PD patients that experimented a high score (>12) in SCOPA-AUT (Scale for Outcomes in PD-Autonomic scale). Conclusions. These results confirm the effect of affective perception of pain in life quality of PD patients, indicating the critical role of autonomic symptoms in the modulation of the influence of pain on quality of life and showing the possible utility of dysautonomia as clinical prognostic indicator of quality of life in PD patients affected by pain. PMID:27239367

  8. DTIPrep: quality control of diffusion-weighted images.

    PubMed

    Oguz, Ipek; Farzinfar, Mahshid; Matsui, Joy; Budin, Francois; Liu, Zhexing; Gerig, Guido; Johnson, Hans J; Styner, Martin

    2014-01-01

    In the last decade, diffusion MRI (dMRI) studies of the human and animal brain have been used to investigate a multitude of pathologies and drug-related effects in neuroscience research. Study after study identifies white matter (WM) degeneration as a crucial biomarker for all these diseases. The tool of choice for studying WM is dMRI. However, dMRI has inherently low signal-to-noise ratio and its acquisition requires a relatively long scan time; in fact, the high loads required occasionally stress scanner hardware past the point of physical failure. As a result, many types of artifacts implicate the quality of diffusion imagery. Using these complex scans containing artifacts without quality control (QC) can result in considerable error and bias in the subsequent analysis, negatively affecting the results of research studies using them. However, dMRI QC remains an under-recognized issue in the dMRI community as there are no user-friendly tools commonly available to comprehensively address the issue of dMRI QC. As a result, current dMRI studies often perform a poor job at dMRI QC. Thorough QC of dMRI will reduce measurement noise and improve reproducibility, and sensitivity in neuroimaging studies; this will allow researchers to more fully exploit the power of the dMRI technique and will ultimately advance neuroscience. Therefore, in this manuscript, we present our open-source software, DTIPrep, as a unified, user friendly platform for thorough QC of dMRI data. These include artifacts caused by eddy-currents, head motion, bed vibration and pulsation, venetian blind artifacts, as well as slice-wise and gradient-wise intensity inconsistencies. This paper summarizes a basic set of features of DTIPrep described earlier and focuses on newly added capabilities related to directional artifacts and bias analysis. PMID:24523693

  9. DTIPrep: quality control of diffusion-weighted images

    PubMed Central

    Oguz, Ipek; Farzinfar, Mahshid; Matsui, Joy; Budin, Francois; Liu, Zhexing; Gerig, Guido; Johnson, Hans J.; Styner, Martin

    2014-01-01

    In the last decade, diffusion MRI (dMRI) studies of the human and animal brain have been used to investigate a multitude of pathologies and drug-related effects in neuroscience research. Study after study identifies white matter (WM) degeneration as a crucial biomarker for all these diseases. The tool of choice for studying WM is dMRI. However, dMRI has inherently low signal-to-noise ratio and its acquisition requires a relatively long scan time; in fact, the high loads required occasionally stress scanner hardware past the point of physical failure. As a result, many types of artifacts implicate the quality of diffusion imagery. Using these complex scans containing artifacts without quality control (QC) can result in considerable error and bias in the subsequent analysis, negatively affecting the results of research studies using them. However, dMRI QC remains an under-recognized issue in the dMRI community as there are no user-friendly tools commonly available to comprehensively address the issue of dMRI QC. As a result, current dMRI studies often perform a poor job at dMRI QC. Thorough QC of dMRI will reduce measurement noise and improve reproducibility, and sensitivity in neuroimaging studies; this will allow researchers to more fully exploit the power of the dMRI technique and will ultimately advance neuroscience. Therefore, in this manuscript, we present our open-source software, DTIPrep, as a unified, user friendly platform for thorough QC of dMRI data. These include artifacts caused by eddy-currents, head motion, bed vibration and pulsation, venetian blind artifacts, as well as slice-wise and gradient-wise intensity inconsistencies. This paper summarizes a basic set of features of DTIPrep described earlier and focuses on newly added capabilities related to directional artifacts and bias analysis. PMID:24523693

  10. Image quality of microcalcifications in digital breast tomosynthesis: Effects of projection-view distributions

    SciTech Connect

    Lu, Yao; Chan, Heang-Ping; Wei, Jun; Goodsitt, Mitch; Carson, Paul L.; Hadjiiski, Lubomir; Schmitz, Andrea; Eberhard, Jeffrey W.; Claus, Bernhard E. H.

    2011-10-15

    distributions on spatial blurring depended on the directions. In the X-direction (perpendicular to the chestwall), the normalized line profiles of the calcifications reconstructed with the different PV distributions were similar in terms of FWHM; the differences in the FWHMs between the different PV distributions were less than half a pixel. In the Y-direction (x-ray source motion), the normalized line profiles of the calcifications reconstructed with PVs acquired with a narrow angular range or a large fraction of PVs at small angles had smaller FWHMs and thus less blurring of the line profiles. In addition, PV distributions with a narrow angular range or a large fraction of PVs at small angles yielded slightly higher CNR than those with a wide angular range for small, subtle microcalcifications; however, PV distributions had no obvious effect on CNR for relatively large microcalcifications. Conclusions: PV distributions affect the image quality of DBT. The relative importance of the impact depends on the characteristics of the signal and the direction (perpendicular or parallel) relative to the direction of x-ray source motion. For a given number of PVs, the angular range and the distribution of the PVs affect the degree of in-plane and interplane blurring in opposite ways. The design of the scan parameters of tomosy