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Sample records for color rendering index

  1. Excellent color rendering indexes of multi-package white LEDs.

    PubMed

    Oh, Ji Hye; Yang, Su Ji; Sung, Yeon-Goog; Do, Y R

    2012-08-27

    This study introduces multi-package white light-emitting diodes (LEDs) system with the ability to realize high luminous efficacy and an excellent color rendering index (CRI, R a) using the R B,M A B,M G B,M C B (R B,M A B,M G B,M denoted as a long-pass dichroic filter (LPDF)-capped, monochromatic red, amber and green phosphor converted-LED (pc-LED) pumped by a blue LED chip, and C B denoted as a cyan and blue mixed pc-LED pumped by a blue LED) system. The luminous efficacy and color rendering index (CRI) of multi-package white LED systems are compared while changing the concentration of the cyan phosphor used in the paste of a cyan-blue LED package and the driving current of individual LEDs in multi-package white LEDs at correlated color temperatures (CCTs) ranging from 6,500 K (cold white) to 2,700 K (warm white) using a set of eight CCTs as specified by the American National Standards Institute (ANSI) standard number C78.377-2008. A R B,M A B,M G B,M C B white LED system provides high luminous efficacy (≥ 96 lm/W) and a color rendering index (≥ 91) encompassing the complete CCT range. We also compare the optical properties of the R B,M A B,M G B,M C B system with those of the R B,M A B,M G B,M B and RAGB (red, amber, green, and blue semiconductor-type narrow-spectrum-band LEDs) systems. It can be expected that the cyan color added to a blue LED in multi-package white LEDs based on LPDF-capped, phosphor-converted monochromatic LEDs will meet the needs of the high-quality, highly efficient, full-color white LED lighting market in the near future. PMID:23037079

  2. Color temperature tunable white-light LED cluster with extrahigh color rendering index.

    PubMed

    Zhang, Minhao; Chen, Yu; He, Guoxing

    2014-01-01

    The correlated color temperature (CCT) tunable white-light LED cluster with extrahigh color rendering property has been found by simulation and fabricated, which consists of three WW LEDs (CCT = 3183 K), one red LED (634.1 nm), one green LED (513.9 nm), and one blue LED (456.2 nm). The experimental results show that this cluster can realize the CCT tunable white-lights with a color rendering index (CRI) above 93, special CRI R9 for strong red above 90, average value of the special CRIs of R9 to R12 for the four saturated colors (red, yellow, green, and blue) above 83, and luminous efficacies above 70 lm/W at CCTs of 2719 K to 6497 K. PMID:24578665

  3. Color temperature tunable white-light light-emitting diode clusters with high color rendering index.

    PubMed

    He, Guoxing; Zheng, Lihong

    2010-08-20

    A model for LED spectra at different drive currents is established. The simulation program of color rendering of a white-light LED cluster is developed according to the principle of additive color mixtures. The program can predict not only the spectral power distribution, chromaticity coordinates, correlated color temperature (CCT), and color rendering index (CRI), but also the drive currents of LEDs, luminous flux, input power, and luminous efficacy of white-light LED clusters. Three types of CCT tunable white-light LED clusters [warm-white/red/green/blue (WW/R/G/B), neutral-white (NW)/R/G/B, and cool-white/R/amber/G clusters] with high CRI are found by simulation analysis and realized in our laboratory. The experimental results show that the WW/R/G/B cluster can realize CCT tunable white light with high CRIs (above 90) but lower luminous efficacies (below 65 lm/W), and that the NW/R/G/B cluster can realize CCT tunable white light with high CRIs (above 86), as well as high luminous efficacies (above 64 lm/W). PMID:20733639

  4. General Color Rendering Index of Wall-stabilized Arc of Water-cooled Vortex Type

    NASA Astrophysics Data System (ADS)

    Nakamura, Takaya; Yanagi, Kentaro; Yamamoto, Shinji; Iwao, Toru

    2015-11-01

    The arc lighting to obtain the environment to evacuate, save the life, keep the safety and be comfortable are focus on. The lack of radiation intensity and color rendering is problem because of inappropriate energy balance. Some researchers have researched the high-intensity discharge (HID) lamp which is one of the arc lamp with metal vapor, and the line spectrum emitted from the metal vapor is used for improvement of color rendering spectrum. The broad spectrum emitted from continuous spectrum is needed for improvement of color rendering spectrum. It is necessary to perform the calculation using the wall-stabilized arc to equalize the contribution to the temperature distribution which the convection gives it to bell-shaped form in the gas flow-stabilized arc for the axial distance. This research elucidates the development of the argon wall-stabilized arc in order to control the spectrum for improvement of color rendering spectrum with controlling the current and radius. The color rendering is measured by the general color rendering index. As a result, the general color rendering index increases with increasing the current and radius of the wall-stabilized arc in the case of simulation. However, it doesn't change so much in the case of experiment. Therefore, the radius, i.e. the arc temperature distribution, is more important factor.

  5. Emission Characteristics of High Color Rendering Index Low-Pressure Xe and CO ICP's Light Source

    NASA Astrophysics Data System (ADS)

    Nazri, Ahmad; Kondo, Akira; Motomura, Hideki; Jinno, Masafumi

    High color rendering index (CRI) has been obtained from mercury-free ICP’s lamp. Due to the strong demand on the development of mercury-free light sources, the authors investigated xenon and CO as an alternative element. These rare (Xe) and molecule (CO) gases have been used as a substitute for mercury as the environmental problems related necessitate the development of new type of light sources. The target of this study is to develop a new type of mercury-free lamp without using a phosphor where the authors concentrate on how to obtain a strong visible light instead of UV. In this paper, the colors, luminance and emission characteristics of these types of mercury-free ICP’s lamp is discussed. Without the use of phosphor, the authors obtained a good color rendering from xenon and CO ICP’s lamp where their CRI’s above 90. A strong continuum emission in visible region is obtained where luminance are ranged from 2000 to 25000 cd/m2 at 100 W of input power. Spectral distribution shows the continuum emissions are similar to the daylight distribution and chromaticity diagrams shows they are close to white region in color coordinates and color temperatures bringing a high index of the lamp’s color rendering.

  6. Case Study on Combination of Fluorescent Materials for White LED to Obtain High Color Rendering Indexes

    NASA Astrophysics Data System (ADS)

    Nayama, Shunsuke; Itoh, Kunio

    This letter reports on white-LED with high color rendering property. We realized the white-LED whose average Color Rendering Index (CRI) is as high as 94.2 by applying the commercial Red, Yellow, Green and Blue phosphors to near ultraviolet-LED. So far as we know, this value is the highest ever attained in white-LED around the color temperature of 5500[K]. In order to realize the good Ra (average CRI), we made a CRI simulator and simulated the spectrum distribution of white-LED with good Ra. The spectrum distribution obtained by this simulation was proved to be very useful as a landmark for realizing a prototype white-LED with good Ra.

  7. Approach for optimization of the color rendering index of light mixtures.

    PubMed

    Lin, Ku Chin

    2010-07-01

    The general CIE color rendering index (CRI) of light is an important index to evaluate the quality of illumination. However, because of the complexity in measurement of the rendering ability under designated constraints, an approach for general mathematical formulation and global optimization of the rendering ability of light emitting diode (LED) light mixtures is difficult to develop. This study is mainly devoted to developing mathematical formulation and a numerical method for the CRI optimization. The method is developed based on the so-called complex method [Computer J.8, 42 (1965); G. V. Reklaitis et al., Engineering Optimization-Methods and Applications (Wiley, 1983)] with modifications. It is first applicable to 3-color light mixtures and then extended to a hierarchical and iterative structure for higher-order light mixtures. The optimization is studied under the constraints of bounded relative intensities of the light mixture, designated correlated color temperature (CCT), and the required approximate white of the light mixture. The problems of inconsistent constraints and solutions are addressed. The CRI is a complicated function of the relative intensities of the compound illuminators of the mixture. The proposed method requires taking no derivatives of the function and is very adequate for the optimization. This is demonstrated by simulation for RGBW LED light mixtures. The results show that global and unique convergence to the optimal within required tolerances for CRI and spatial dispersivity is always achieved. PMID:20596135

  8. Color-converting combinations of nanocrystal emitters for warm-white light generation with high color rendering index

    NASA Astrophysics Data System (ADS)

    Nizamoglu, Sedat; Zengin, Gulis; Demir, Hilmi Volkan

    2008-01-01

    Warm-white light emitting diodes with high color rendering indices are required for the widespread use of solid state lighting especially indoors. To meet these requirements, we propose and demonstrate warm-white hybrid light sources that incorporate the right color-converting combinations of CdSe /ZnS core-shell nanocrystals hybridized on InGaN /GaN LEDs for high color rendering index. Three sets of proof-of-concept devices are developed to generate high-quality warm-white light with (1) tristimulus coordinates (x,y)=(0.37,0.30), luminous efficacy (LE)=307lm/W, color rending index (CR)=82.4, and correlated color temperature (CCT)=3228K; (2) (x,y)=(0.38,0.31), LE =323lm/W, CRI =81.0, and CCT =3190K; and (3) (x,y)=(0.37,0.30), LE =303lm/W, CRI =79.6, and CCT =1982K.

  9. Dimmable sunlight-like organic light emitting diodes with ultra-high color rendering index

    NASA Astrophysics Data System (ADS)

    Wu, Jin-Han; Chi, Chien-An; Chiang, Chang-Lin; Chen, Guan-Yu; Lin, Yi-Ping; Chen, Cheng-Chang; Ho, Shu-Yi; Chen, Shih-Pu; Li, Jung-Yu

    2016-05-01

    We propose novel dimmable sunlight-like white organic light-emitting diodes that were fabricated using three luminophores to form an emitting spectrum similar to black body radiation at 2250 K with ultra-high color rendering index (CRI) value of 91, which nearly remained the constant at various luminance values ranging from 100 to more than 2500 cd/m2 at Commission Internationale de l'Eclairage chromaticity coordinates of (0.51, 0.41). Introducing charge modification layers suppressed the energy transfer between the emitting material layers and increased the probability of carrier recombination. Moreover, we reveal that covering long-wavelength ranges played a vital role in achieving high CRI values; the CRI values of a spectrum artificially shifted toward a long-wavelength direction (from 610 to 620 nm) remained constant, whereas those of a spectrum shifted toward a short-wavelength direction (from 610 to 600 nm) dropped to 79.

  10. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    NASA Astrophysics Data System (ADS)

    Miao, Yan-Qin; Gao, Zhi-Xiang; Zhang, Ai-Qin; Li, Yuan-Hao; Wang, Hua; Jia, Hu-Sheng; Liu, Xu-Guang; Tsuboi, Taijuf

    2015-05-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0927), the International Science & Technology Cooperation Program of China (Grant No. 2012DFR50460), the National Natural Science Foundation of China (Grant Nos. 21101111 and 61274056), and the Shanxi Provincial Key Innovative Research Team in Science and Technology, China (Grant No. 2012041011).

  11. Linear calculation model for prediction of color rendering index performance associated with correlated color temperature of white light-emitting diodes with two phosphors

    NASA Astrophysics Data System (ADS)

    Sun, Ching-Cherng; Chen, Ching-Yi; Chang, Jung-Hsuan; Yang, Tsung-Hsun; Ji, Wei-Shih; Jeng, Yow-Shiuan; Wu, Hsin-Mei

    2012-05-01

    Linear calculation models are proposed and demonstrated to evaluate the color rendering index (CRI) performance associated with the correlated color temperature (CCT) of a white light emitting diode with two phosphors. All the three proposed models are simple and easy, and the error in predicting the CRI is within 1, while the deviation of the CCT is around 300 K and less. Such models can be useful in evaluating the chromatic performance of a specific recipe with two phosphors.

  12. A spectrum-adjusted white organic light-emitting diode for the optimization of luminous efficiency and color rendering index

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Chen, Shu-ming

    2015-01-01

    High luminous efficiency and high color rendering index (CRI) are both the foremost factors for white organic light-emitting diodes (WOLEDs) to serve as next generation solid-state lighting sources. In this paper, we show that both luminous efficiency and CRI can be improved by adjusting the green/red spectra of WOLEDs. With green emission spectra matching with the human photopic curve, the WOLEDs exhibit higher luminous efficiency and higher CRI. Theoretical calculation shows that by tuning the white emission spectra to maximally match with the human photopic curve, the luminous efficiency can be improved by 41.8% without altering the color coordinates, the color correlated temperature (CCT) and the external quantum efficiency (EQE) of the WOLEDs.

  13. High-Efficiency WOLEDs with High Color-Rendering Index based on a Chromaticity-Adjustable Yellow Thermally Activated Delayed Fluorescence Emitter.

    PubMed

    Li, Xiang-Long; Xie, Gaozhan; Liu, Ming; Chen, Dongcheng; Cai, Xinyi; Peng, Junbiao; Cao, Yong; Su, Shi-Jian

    2016-06-01

    A chromaticity-adjustable yellow thermally activated delayed fluorescence (TADF) material, PXZDSO2 as a triplet harvester provides a rational device concept, giving two-color and three-color pure organic white organic light-emitting diodes (WOLEDs) with unprecedented color-rendering index of 95 and external quantum efficiency of 19.2%. PMID:27062637

  14. High Color-Rendering-index Hybrid White LEDs Employing CdSe/ZnS Core/Shell Quantum Dots.

    PubMed

    Chang, Yajing; Sun, Dapeng; Zhang, Zhongping; Zhang, Yugang; Yao, Xudong; Jiang, Danlu; Yu, Yalan; Mi, Longfei; Chen, Lei; Zhong, Honghai; Jiang, Yang

    2016-01-01

    Hybrid white LEDs were constructed by leveraging a combination of CdSe/ZnS core/shell QDs and YAG: Ce³⁺ phosphors. The CdSe/ZnS core/shell QDs were synthesized by a two-step process in which CdSe QDs were first prepared via a hot-injection method, followed by ZnS coating through a facile single-molecular precursor approach. The resultant red-emitting CdSe/ZnS QDs showed decent fluorescent quantum yielding (36%). The resultant hybrid white LEDs--that based on CdSe/ZnS QDs and solid-state-reaction-processed YAG: Ce³⁺ phosphors--showed good luminescence properties, including bright warm light, a high color rendering index of 91.3, a low color temperature of 4965 K and a luminous efficiency of 44.22 lm/W. Moreover, increased luminous intensity has been observed in the presence of increased forward current without luminescence saturation, promising an ideal approach to construct warm-white LEDs with excellent color rendering properties. PMID:27398506

  15. A white organic light-emitting diode with ultra-high color rendering index, high efficiency, and extremely low efficiency roll-off

    NASA Astrophysics Data System (ADS)

    Sun, Ning; Zhao, Yongbiao; Zhao, Fangchao; Chen, Yonghua; Yang, Dezhi; Chen, Jiangshan; Ma, Dongge

    2014-07-01

    Ultra-high color rendering index (>90) is considered to be crucial for lighting in museum, studio, art gallery, medical, and wide-color-gamut display. However, all relevant works reported to exhibit ultra-high color rendering index suffer from a low efficiency and serious efficiency roll-off. In order to achieve ultra-high color rendering index and maintain high device efficiency at the same time, we incorporate four organic dyes in an elaborate device structure. The resulting white organic light-emitting diode exhibits rather high color rendering index up to 94 over a wide brightness range and yields electroluminescence efficiencies up to 14.2%, 26.0 cd/A, and 21.9 lm/W at the brightness of 1000 cd m-2, which are the highest values reported to date for such ultra-high color rendering index white organic light-emitting diodes. In addition, the current issue on efficiency roll-off is well resolved in the resulting device. The critical current density jc is as high as 203 mA cm-2.

  16. The thermal stability performances of the color rendering index of white light emitting diodes with the red quantum dots encapsulation

    NASA Astrophysics Data System (ADS)

    Yin, Luqiao; Bai, Yang; Zhou, Jie; Cao, Jin; Sun, Xiaowei; Zhang, Jianhua

    2015-04-01

    Red phosphors are the traditional material used to improve the color rendering index (CRI) of white light emitting diode (WLEDs). In this paper, red quantum dots (QDs) were fabricated and coated on the blue LED chip to replace the red phosphors. By comparing the thermal performances of the CRI for the two WLEDs, we found that WLEDs with the encapsulation of yellow phosphors and red QDs exhibited higher CRI and lower sensitivity to temperature than those with the encapsulation of yellow and red phosphors. The CRI of WLEDs with yellow phosphors and red QDs was 90.9, and its range ability was only 0.3 when the environment temperature changed from 25 °C to 100 °C, while the CRI of WLEDs with yellow and red phosphors was as low as 81.8, and the change of CRI was 2.2 during the same temperature variation.

  17. Highly efficient semitransparent polymer solar cells with color rendering index approaching 100 using one-dimensional photonic crystal.

    PubMed

    Yu, Wenjuan; Jia, Xu; Long, Yongbing; Shen, Liang; Liu, Yan; Guo, Wenbin; Ruan, Shengping

    2015-05-13

    Window application is the important aim for semitransparent solar cells (STPSC) investigation. Here, we demonstrate a method to achieve significantly improved color rendering index (CRI), depressed chromaticity difference (DC), and enhanced power conversion efficiency (PCE) simultaneously by introducing the one-dimensional photonic crystals (1DPCs) Bragg reflector structure onto the STPSC. The device performance is studied from aspects of color perception, electrical properties, and theoretical optical simulations. The STPSCs exhibit achromatic transparency nature color perceptions, especially for the STPSCs with 1DPCs (pairs ≥ 3) under AM 1.5G illumination light source, standard illuminant D65, and standard illuminant A. The excellent CRI is approaching 97 with lower DC about 0.0013 for the device with 5 pairs of 1DPC illumined by AM 1.5G illumination light source. At the same time, the PCE of STPSC devices with 5 pairs of 1DPC was improved from 4.87 ± 0.14% to 5.31 ± 0.13% compared to without. This method provides a facilitative approach to realizing excellent SPTSC window application. PMID:25854166

  18. Color rendering of color camera data

    NASA Technical Reports Server (NTRS)

    Wandell, Brian A.

    1986-01-01

    Conditions under which a computational procedure can be applied to arbitrary camera sensors to permit estimation of the human photoreceptor response are considered. The adopted procedures recover the effective surface reflectance at the time of measurement, and the reflectance estimates depend not only on the surface, but upon the viewing geometry. The present method for color rendering assumes that the observer's state of adaptation at the time of viewing the original and the rendered images is the same. The analysis aids in specifying which classes of surfaces are required to be accurately rendered, and for which surfaces some error can be tolerated.

  19. Museum lighting for golden artifacts, with low correlated color temperature, high color uniformity and high color rendering index, using diffusing color mixing of red, cyan, and white-light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Thorseth, Anders; Corell, Dennis D.; Poulsen, Peter B.; Hansen, Søren S.; Dam-Hansen, Carsten

    2012-03-01

    Museum lighting present challenges due to the demand for a high color rendering index (CRI), color uniformity and the damaging effects of both visible and invisible radiation. Golden objects are furthermore normally displayed with illumination which has a correlated color temperature (CCT) of 2200 K, a CCT that is not commercially available from single LEDs. An LED system that conforms with these requirements has been developed and implemented at The Royal Danish Collection at Rosenborg Castle. Color mixing of commercial LEDs (red, cyan, and white) was employed to achieve the spectral power distribution needed for the CCT and a CRI above 90, for all CRI test color samples. Replacing the traditional low voltage incandescent lighting has shown energy saving above 70 %. Harmful IR radiation was reduced by 99 %. Temperature fluctuations in the display cases were reduced from several degrees Celsius to below one, despite the fact that the lighting units were placed within the display case. Spatial color uniformity of the illumination and uniformly colored shadows was achieved by use of a highly diffusing reflector dish which avoids direct illumination from the LEDs.

  20. Excellent color rendering index and high quantum efficiency of rare-earth-free fluosilicate glass for single-phase white light phosphor.

    PubMed

    Yuan, Ye; Zheng, Ruilin; Lu, Qiang; Zhang, Weitao; Zheng, Jiajin; Wei, Wei

    2016-07-01

    A rare-earth-free Sn-doped fluosilicate (SF) glass for single-phase white light phosphor has been investigated, which has a high color rendering index (98.3) and a quantum efficiency (85%). Moreover, by combining with a 280 nm LED chip directly, the Commission Internationale de l'Éclairage (CIE) coordinate (x=0.32, y=0.33) and correlated color temperature (5620 K) are close to the standard white light illumination. SF glass is a promising candidate as an alternative single-phase white light phosphor for use in general lighting devices. PMID:27367117

  1. High color rendering index white light emitting diodes fabricated from a combination of carbon dots and zinc copper indium sulfide quantum dots

    SciTech Connect

    Sun, Chun; Liu, Wenyan; Zhang, Xiaoyu; Zhang, Yu E-mail: wyu6000@gmail.com; Wang, Yu; Kalytchuk, Sergii; Kershaw, Stephen V.; Rogach, Andrey L.; Zhang, Tieqiang; Zhao, Jun; Yu, William W. E-mail: wyu6000@gmail.com

    2014-06-30

    In a line with most recent trends in developing non-toxic fluorescent nanomaterials, we combined blue emissive carbon dots with green and red emissive zinc copper indium sulfide (ZCIS) core/shell quantum dots (QDs) to achieve white light-emitting diodes (WLEDs) with a high color rendering index of 93. This indicates that ZCIS QDs, with their broad emission bands, can be employed to effectively make up the emission of carbon dots in the yellow and red regions to produce WLEDs in the wide region of color temperature by tuning the volume ratio of these constituting luminophores. Their electroluminescence characteristics including color rendering index, Commission Internationale de l'Eclairage (CIE) color coordinates, and color temperatures were evaluated as a function of forward current. The CIE-1931 chromaticity coordinates of the as-prepared WLEDs, exhibiting good stability, were slightly shifted from (0.321, 0.312) at 10 mA to (0.351, 0.322) at 30 mA, which was mainly caused by the different thermal quenching coefficients of carbon dots and ZCIS QDs.

  2. A photometric investigation of ultra-efficient LEDs with high color rendering index and high luminous efficacy employing nanocrystal quantum dot luminophores.

    PubMed

    Erdem, Talha; Nizamoglu, Sedat; Sun, Xiao Wei; Demir, Hilmi Volkan

    2010-01-01

    We report a photometric study of ultra-efficient light emitting diodes (LEDs) that exhibit superior color rendering index (CRI) and luminous efficacy of optical radiation (LER) using semiconductor quantum dot nanocrystal (NC) luminophores. Over 200 million systematically varied NC-LED designs have been simulated to understand feasible performance in terms of CRI vs. LER. We evaluated the effects of design parameters including peak emission wavelength, full-width-at-half-maximum, and relative amplitudes of each NC color component on LED performance. Warm-white LEDs with CRI >90 and LER >380 lm/W at a correlated color temperature of 3000 K are shown to be achieved using nanocrystal luminophores. PMID:20173854

  3. Antireflective sub-wavelength structures for improvement of the extraction efficiency and color rendering index of monolithic white light-emitting diode.

    PubMed

    Ou, Yiyu; Corell, Dennis Dan; Dam-Hansen, Carsten; Petersen, Paul Michael; Ou, Haiyan

    2011-03-14

    We have theoretically investigated the influence of antireflective sub-wavelength structures on a monolithic white light-emitting diode (LED). The simulation is based on the rigorous coupled wave analysis (RCWA) algorithm, and both cylinder and moth-eye structures have been studied in the work. Our simulation results show that a moth-eye structure enhances the light extraction efficiency over the entire visible light range with an extraction efficiency enhancement of up to 26 %. Also for the first time to our best knowledge, the influence of sub-wavelength structures on both the color rendering index (CRI) and the correlated color temperature (CCT) of the monolithic white LED have been demonstrated. The CRI of the monolithic white LED could be improved from 92.68 to around 94 by applying a cylinder structure, and the CCT could be modified in a very large range with appropriate design of the cylinder structure. PMID:21445218

  4. An experiment on the color rendering of different light sources

    NASA Astrophysics Data System (ADS)

    Fumagalli, Simonetta; Bonanomi, Cristian; Rizzi, Alessandro

    2013-02-01

    The color rendering index (CRI) of a light source attempts to measure how much the color appearance of objects is preserved when they are illuminated by the given light source. This problem is of great importance for various industrial and scientific fields, such as lighting architecture, design, ergonomics, etc. Usually a light source is specified through the Correlated Color Temperature or CCT. However two (or more) light sources with the same CCT but different spectral power distribution can exist. Therefore color samples viewed under two light sources with equal CCTs can appear different. Hence, the need for a method to assess the quality of a given illuminant in relation to color. Recently CRI has had a renewed interest because of the new LED-based lighting systems. They usually have a color rendering index rather low, but good preservation of color appearance and a pleasant visual appearance (visual appeal). Various attempts to develop a new color rendering index have been done so far, but still research is working for a better one. This article describes an experiment performed by human observers concerning the appearance preservation of color under some light sources, comparing it with a range of available color rendering indices.

  5. High color rendering index WLED based on YAG:Ce phosphor and CdS/ZnS core/shell quantum dots

    NASA Astrophysics Data System (ADS)

    Shen, Changyu; Li, Ke

    2009-08-01

    White LED combining of blue chip and YAG:Ce phosphor suffers from a red spectral deficiency, resulting in a relatively low value of color rendering index (CRI). In our study, for an effort to improve color rendering properties of YAG:Ce phosphor-based white LEDs, highly luminescent red-orange emitting CdS/ZnS QDs were blended with YAG:Ce phosphors. Core/shell CdS/ZnS quantum dots with the emission wavelength of 618nm, was synthesized by thermal deposition using cadmium oxide and selenium as precursors in a hot lauric acid and hexadecylamine trioctylphosphine oxide hybrid. YAG:Ce phosphor was synthesized by high-temperature solid state reaction at 900-1200°C in a slightly reducing atmosphere for 4 hours. Blends of phosphors and QDs exhibited the prominent spectral evolution with an increasing content of QDs. A hybrid white LED, which combines a blue LED with the blend of YAG phosphor and QDs with a weight ratio of 1.5:1,was demonstrated with an improved CRI value of 86.

  6. Bicolor Mn-doped CuInS{sub 2}/ZnS core/shell nanocrystals for white light-emitting diode with high color rendering index

    SciTech Connect

    Huang, Bo; Dai, Qian; Zhang, Huichao; Liao, Chen; Cui, Yiping; Zhang, Jiayu; Zhuo, Ningze; Jiang, Qingsong; Shi, Fenghua; Wang, Haibo

    2014-09-07

    We synthesized bicolor Mn-doped CuInS{sub 2} (CIS)/ZnS core/shell nanocrystals (NCs), in which Mn{sup 2+} ions and the CIS core were separated with a ZnS layer, and both Mn{sup 2+} ions and CIS cores could emit simultaneously. Transmission electron microscopy and powder X-ray diffraction measurements indicated the epitaxial growth of ZnS shell on the CuInS{sub 2} core, and electron paramagnetic resonance spectrum indicated that Mn{sup 2+} ions were on the lattice points of ZnS shell. By integrating these bicolor NCs with commercial InGaN-based blue-emitting diodes, tricolor white light-emitting diodes with color rendering index of 83 were obtained.

  7. Color rendering indices in global illumination methods

    NASA Astrophysics Data System (ADS)

    Geisler-Moroder, David; Dür, Arne

    2009-02-01

    Human perception of material colors depends heavily on the nature of the light sources used for illumination. One and the same object can cause highly different color impressions when lit by a vapor lamp or by daylight, respectively. Based on state-of-the-art colorimetric methods we present a modern approach for calculating color rendering indices (CRI), which were defined by the International Commission on Illumination (CIE) to characterize color reproduction properties of illuminants. We update the standard CIE method in three main points: firstly, we use the CIELAB color space, secondly, we apply a Bradford transformation for chromatic adaptation, and finally, we evaluate color differences using the CIEDE2000 total color difference formula. Moreover, within a real-world scene, light incident on a measurement surface is composed of a direct and an indirect part. Neumann and Schanda1 have shown for the cube model that interreflections can influence the CRI of an illuminant. We analyze how color rendering indices vary in a real-world scene with mixed direct and indirect illumination and recommend the usage of a spectral rendering engine instead of an RGB based renderer for reasons of accuracy of CRI calculations.

  8. Spectral optimization of warm-white light-emitting diode lamp with both color rendering index (CRI) and special CRI of R9 above 90

    NASA Astrophysics Data System (ADS)

    He, Guoxing; Xu, Jing; Yan, Huafeng

    2011-09-01

    The optimal spectra of the warm-white LED (WWLED) lamp consisting of AlGaInP red LED and the p-W LED packaged by combining silicate green and orange phosphors with a InGaN blue LED die was obtained by nonlinear program for maximizing the luminous efficacy of radiation while both color rendering index (CRI) and special CRI of R9 for strong red above 90 at correlated color temeratures (CCTs) of 2700 K. The optimal peak wavelengths of red LED, blue LED die, silicate green and orange phosphors are 626 nm, 454 nm, 535 nm and 584 nm, respectively. Their optimal relative radation fluxs are 9.7%, 33.4 %, 26.1 %, 30.8 %, respectively. The real WWLED lamp with CCT of 2653 K, CRI of 90, R9 of 94 and R(9-12) of 88, as well as luminous efficacy (LE) of 80.2 lm/W have been realized. Furthermore, the WWLED lamp can realized CCT tunable warm-white-light with CRIs of 86 ˜ 93, R9s of 86 ˜ 95 and LEs of 78.2 ˜ 80.3 lm/W at CCTs of 2392 K to 3014 K by adjusting drive current of the red LED.

  9. Warm-white light-emitting diode with high color rendering index fabricated by combining trichromatic InGaN emitter with single red phosphor.

    PubMed

    Sheu, Jinn-Kong; Chen, Fu-Bang; Wang, Yen-Chin; Chang, Chih-Chiang; Huang, Shih-Hsien; Liu, Chun-Nan; Lee, Ming-Lun

    2015-04-01

    We present a trichromatic GaN-based light-emitting diode (LED) that emits near-ultraviolet (n-UV) blue and green peaks combined with red phosphor to generate white light with a low correlated color temperature (CCT) and high color rendering index (CRI). The LED structure, blue and green unipolar InGaN/GaN multiple quantum wells (MQWs) stacked with a top p-i-n structure containing an InGaN/GaN MQW emitting n-UV light, was grown epitaxially on a single substrate. The trichromatic LED chips feature a vertical conduction structure on a silicon substrate fabricated through wafer bonding and laser lift-off techniques. The blue and green InGaN/GaN MQWs were pumped with n-UV light to re-emit low-energy photons when the LEDs were electrically driven with a forward current. The emission spectrum included three peaks at approximately 405, 468, and 537 nm. Furthermore, the trichromatic LED chips were combined with red phosphor to generate white light with a CCT and CRI of approximately 2900 and 92, respectively. PMID:25968789

  10. Image-based color ink diffusion rendering.

    PubMed

    Wang, Chung-Ming; Wang, Ren-Jie

    2007-01-01

    This paper proposes an image-based painterly rendering algorithm for automatically synthesizing an image with color ink diffusion. We suggest a mathematical model with a physical base to simulate the phenomenon of color colloidal ink diffusing into absorbent paper. Our algorithm contains three main parts: a feature extraction phase, a Kubelka-Munk (KM) color mixing phase, and a color ink diffusion synthesis phase. In the feature extraction phase, the information of the reference image is simplified by luminance division and color segmentation. In the color mixing phase, the KM theory is employed to approximate the result when one pigment is painted upon another pigment layer. Then, in the color ink diffusion synthesis phase, the physically-based model that we propose is employed to simulate the result of color ink diffusion in absorbent paper using a texture synthesis technique. Our image-based ink diffusing rendering (IBCIDR) algorithm eliminates the drawback of conventional Chinese ink simulations, which are limited to the black ink domain, and our approach demonstrates that, without using any strokes, a color image can be automatically converted to the diffused ink style with a visually pleasing appearance. PMID:17218741

  11. High color rendering index of remote-type white LEDs with multi-layered quantum dot-phosphor films and short-wavelength pass dichroic filters

    NASA Astrophysics Data System (ADS)

    Yoon, Hee Chang; Oh, Ji Hye; Do, Young Rag

    2014-09-01

    This paper introduces high color rendering index (CRI) white light-emitting diodes (W-LEDs) coated with red emitting (Sr,Ca)AlSiN3:Eu phosphors and yellowish-green emitting AgIn5S8/ZnS (AIS/ZS) quantum dots (QDs) on glass or a short-wavelength pass dichroic filter (SPDF), which transmit blue wavelength regions and reflect yellow wavelength regions. The red emitting (Sr,Ca)AlSiN3:Eu phosphor film is coated on glass and a SPDF using a screen printing method, and then the yellowish-green emitting AIS/ZS QDs are coated on the red phosphor (Sr,Ca)AlSiN3:Eu film-coated glass and SPDF using the electrospray (e-spray) method.To fabricate the red phosphor film, the optimum amount of phosphor is dispersed in a silicon binder to form a red phosphor paste. The AIS/ZS QDs are mixed with dimethylformamide (DMF), toluene, and poly(methyl methacrylate) (PMMA) for the e-spray coating. The substrates are spin-coated with poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) to fabricate a conductive surface. The CRI of the white LEDs is improved through inserting the red phosphor film between the QD layer and the glass substrate. Furthermore, the light intensities of the multi-layered phosphor films are enhanced through changing the glass substrate to the SPDF. The correlated color temperatures (CCTs) vary as a function of the phosphor concentration in the phosphor paste. The optical properties of the yellowish-green AIS/ZS QDs and red (Sr,Ca)AlSiN3:Eu phosphors are characterized using photoluminescence (PL), and the multi-layered QD-phosphor films are measured using electroluminescence (EL) with an InGaN blue LED (λmax = 450 nm) at 60 mA.

  12. Two Host-Dopant Emitting Systems Realizing Four-Color Emission: A Simple and Effective Strategy for Highly Efficient Warm-White Organic Light-Emitting Diodes with High Color-Rendering Index at High Luminance.

    PubMed

    Zhuang, Xuming; Zhang, Hao; Ye, Kaiqi; Liu, Yu; Wang, Yue

    2016-05-11

    A four-color warm-white organic light-emitting diode employing a simple adjacent two-emitting-layer structure as a blue host-orange dopant/green host-red dopant has been fabricated, which exhibited a stable high electroluminescent performance: an external quantum efficiency of 23.3% and a power efficiency of 63.2 lm W(-1) at an illumination-relevant luminance of 1000 cd m(-2) with a high color-rendering index (CRI) of 92 and maintained high levels of 21.6% and 48.8 lm W(-1) with a CRI value of 93 at the extremely high luminance of 5000 cd m(-2). To our knowledge, this should be the best result so far for a white-light organic light-emitting diode with CRI > 90, simultaneously exhibiting very high efficiencies based on a high luminance level for the solid-state lighting. PMID:27105391

  13. Modulating dual-wavelength multiple quantum wells in white light emitting diodes to suppress efficiency droop and improve color rendering index

    SciTech Connect

    Zhao, Yukun; Wang, Shuai; Zheng, Min; Ding, Wen; Yun, Feng; Su, Xilin; Yang, Xiangrong; Liu, Shuo; Guo, Maofeng; Zhang, Ye

    2015-10-14

    In this paper, gallium nitride (GaN) based white light-emitting diodes (WLEDs) with modulated quantities of blue (In{sub 0.15}Ga{sub 0.85}N) quantum wells (QWs) and cyan QWs (In{sub 0.18}Ga{sub 0.82}N) in multiple QW (MQW) structures have been investigated numerically and experimentally. It is demonstrated that the optical performance of LEDs is sensitive to the quantities of cyan QWs in dual-wavelength MQW structures. Compared to the LEDs with respective 0, 4, and 8 cyan QWs (12 QWs in total), the optical performance of the sample with 6 cyan QWs is the best. The deterioration of the optical performance in the sample with less (4 pairs) cyan QWs or more (8 pairs) cyan QWs than 6 cyan QWs may be ascribed to weakened reservoir effect or more defects induced. Compared to conventional blue LEDs (12 blue QWs), the sample with 6 cyan QWs could effectively suppress the efficiency droop (the experimental droop ratio decreases from 50.3% to 39.5% at 80 A/cm{sup 2}) and significantly improve the color rendering index (CRI, increases from 66.4 to 77.0) simultaneously. We attribute the droop suppression to the strengthened reservoir effect and carrier confinement of deeper QWs (higher indium composition) incorporated in the dual-wavelength MQW structures, which lead to the better hole spreading and enhanced radiative recombination. Meanwhile, the remarkable experimental CRI improvement may result from the wider full-width at half-maximum of electroluminescence spectra and higher cyan intensity in WLED chips with dual-wavelength MQW structures.

  14. Novel Emitting System Based on a Multifunctional Bipolar Phosphor: An Effective Approach for Highly Efficient Warm-White Light-Emitting Devices with High Color-Rendering Index at High Luminance.

    PubMed

    Du, Mingxu; Feng, Yansong; Zhu, Dongxia; Peng, Tai; Liu, Yu; Wang, Yue; Bryce, Martin R

    2016-07-01

    A three-color warm-white organic light-emitting diode employing an efficient phosphor-phosphor type host-guest emitting system achieves efficiencies of 27.3% for external quantum efficiency and 74.5 lm W(-1) for power efficiency at a luminance of 1000 cd m(-2) , which maintained the high levels of 24.3% and 45.8 lm W(-1) at 10 000 cd m(-2) , with a stable color-rendering index of 86-87. PMID:27172456

  15. High color rendering index white LED based on nano-YAG:Ce3+ phosphor hybrid with CdSe/CdS/ZnS core/shell/shell quantum dots

    NASA Astrophysics Data System (ADS)

    Shen, Changyu; Chu, Jinlei; Qian, Feng; Zou, Xin; Zhong, Chuan; Li, Ke; Jin, Shangzhong

    2012-08-01

    To improve the poor color rendering index (CRI) of YAG:Ce-based white light-emitting diode (LED) due to the lack of red spectral component, core/shell/shell CdSe/CdS/ZnS quantum dots (QDs) were synthesized and blended into nano-YAG:Ce3+ phosphors. Prominent spectral evolution has been achieved by increasing the content of QDs. A white LED combining a blue LED with the blends of nano-YAG phosphors and orange- and red-emission QDs with a weight ratio of 1:1:1 was obtained. This kind of white LED showed excellent white light with luminescent efficiency, color coordinates, CRI and correlated color temperature (CCT) of 82.5 lm/W, (0.3264, 0.3255), 91 and 4580 K, respectively.

  16. Color rendering ability and luminous efficacy enhancements in white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Mirhosseini, Roya; Schubert, Martin; Chhajed, Sameer; Cho, Jaehee; Kim, Jong Kyu; Schubert, E. Fred

    2009-08-01

    There exists a fundamental trade-off relation between color rendering index (CRI) and luminous efficacy; in other words, improvements in one are generally detrimental to the other. We analyze and demonstrate through simulation that phosphor-converted white LEDs with dual-blue emitting active regions, as opposed to single-blue emitting active regions, significantly enhance color rendering ability while maximizing the output luminous flux. The improvements are achieved over a broad range of correlated color temperatures.

  17. Sr-Ba combinational effect on spectral broadening of blue (Sr, Ba)5(PO4)3Cl:Ce3+ phosphor for a high color-rendering index

    NASA Astrophysics Data System (ADS)

    Deressa, G.; Park, K. W.; Kim, J. S.

    2016-02-01

    Spectral broadening of blue apatite phosphors (Sr, Ba)5(PO4)3Cl:Ce3+ was achieved by changing Sr-Ba combinations. The blue colors came from 5d1 to 4f1 transitions of Ce3+ ions, and the excitation bands were ranged from 250 nm to 400 nm. The broad Raman spectrum in Sr2.45Ba2.45(PO4)3Cl:Ce3+ supported its highest disorder, leading to the spectral broadening with a half width of 95.5 nm. The temperature dependence showed the emission maintenance of 80% around 100 °C. The 310 nm-pumped white LED was simulated so as to show a color rendering index (Ra) of 74 at white point.

  18. Realistic fetus skin color processing for ultrasound volume rendering

    NASA Astrophysics Data System (ADS)

    Kim, Yun-Tae; Kim, Kyuhong; Park, Sung-Chan; Kang, Jooyoung; Kim, Jung-Ho

    2014-01-01

    This paper proposes realistic fetus skin color processing using a 2D color map and a tone mapping function (TMF) for ultrasound volume rendering. The contributions of this paper are a 2D color map generated through a gamut model of skin color and a TMF that depends on the lighting position. First, the gamut model of fetus skin color is calculated by color distribution of baby images. The 2D color map is created using a gamut model for tone mapping of ray casting. For the translucent effect, a 2D color map in which lightness is inverted is generated. Second, to enhance the contrast of rendered images, the luminance, color, and tone curve TMF parameters are changed using 2D Gaussian function that depends on the lighting position. The experimental results demonstrate that the proposed method achieves better realistic skin color reproduction than the conventional method.

  19. Hybrid 2D photonic crystal-assisted Lu3Al5O12:Ce ceramic-plate phosphor and free-standing red film phosphor for white LEDs with high color-rendering index.

    PubMed

    Park, Hoo Keun; Oh, Ji Hye; Kang, Heejoon; Zhang, Jian; Do, Young Rag

    2015-03-01

    This paper reports the combined optical effects of a two-dimensional (2D) SiNx photonic crystal layer (PCL)-assisted Lu3Al5O12:Ce (LuAG:Ce) green ceramic-plate phosphor (CPP) and a free-standing (Sr,Ca)AlSiN3:Eu red film phosphor to enhance luminous efficacy, color rendering index (CRI), and special CRI (R9) of LuAG:Ce CPP-capped white light-emitting diodes (LEDs) for high-power white LEDs at 350 mA. By introducing the 2D SiNx PCL, the luminous efficacy was improved by a factor of 1.25 and 1.15 compared to that of the conventional flat CPP-capped LED and the thickness-increased CPP-capped LED (with a thickness of 0.15 mm), respectively, while maintaining low color-rendering properties. The combining of the free-standing red film phosphor in the flat CPP-capped, the 2D PCL-assisted CPP-capped, and the thickness-increased CPP-capped LEDs led to enhancement of the CRI and the special CRI (R9); it also led to a decrease of the correlated color temperature (CCT) due to broad wavelength coverage via the addition of red emission. High CRI (94), natural white CCT (4450 K), and acceptable luminous efficacy (71.1 lm/W) were attained from the 2D PCL-assisted LuAG:Ce CPP/free-standing red film phosphor-based LED using a red phosphor concentration of 7.5 wt %. It is expected that the combination of the 2D PCL and the free-standing red film phosphor will be a good candidate for achieving a high-power white CPP-capped LED with excellent CRI. PMID:25675264

  20. Color-rendering indices in global illumination methods

    NASA Astrophysics Data System (ADS)

    Geisler-Moroder, David; Dür, Arne

    2009-10-01

    Human perception of material colors depends heavily on the nature of the light sources that are used for illumination. One and the same object can cause highly different color impressions when lit by a vapor lamp or by daylight, respectively. On the basis of state-of-the-art colorimetric methods, we present a modern approach for the calculation of color-rendering indices (CRI), which were defined by the International Commission on Illumination (CIE) to characterize color reproduction properties of illuminants. We update the standard CIE method in three main points: first, we use the CIELAB color space; second, we apply a linearized Bradford transformation for chromatic adaptation; and finally, we evaluate color differences using the CIEDE2000 total color difference formula. Moreover, within a real-world scene, light incident on a measurement surface is composed of a direct and an indirect part. Neumann and Schanda [Proc. CGIV'06 Conf., Leeds, UK, pp. 283-286 (2006)] have shown for the cube model that diffuse interreflections can influence the CRI of a light source. We analyze how color-rendering indices vary in a real-world scene with mixed direct and indirect illumination and recommend the usage of a spectral rendering engine instead of an RGB-based renderer for reasons of accuracy of CRI calculations.

  1. Novel yellow-emitting Sr8MgLn(PO4)7:Eu2+ (Ln=Y, La) phosphors for applications in white LEDs with excellent color rendering index.

    PubMed

    Huang, Chien-Hao; Chen, Teng-Ming

    2011-06-20

    Eu(2+)-activated Sr(8)MgY(PO(4))(7) and Sr(8)MgLa(PO(4))(7) yellow-emitting phosphors were successfully synthesized by solid-state reactions for applications in excellent color rendering index white light-emitting diodes (LEDs). The excitation and reflectance spectra of these phosphors show broad band excitation and absorption in the 250-450 nm near-ultraviolet region, which is ascribed to the 4f(7) → 4f(6)5d(1) transitions of Eu(2+). Therefore, these phosphors meet the application requirements for near-UV LED chips. Upon excitation at 400 nm, the Sr(8)MgY(PO(4))(7):Eu(2+) and Sr(8)MgLa(PO(4))(7):Eu(2+) phosphors exhibit strong yellow emissions centered at 518, 610, and 611 nm with better thermal stability than (Ba,Sr)(2)SiO(4) (570 nm) commodity phosphors. The composition-optimized concentrations of Eu(2+) in Sr(8)MgLa(PO(4))(7):Eu(2+) and Sr(8)MgY(PO(4))(7):Eu(2+) phosphors were determined to be 0.01 and 0.03 mol, respectively. A warm white-light near-UV LED was fabricated using a near-UV 400 nm chip pumped by a phosphor blend of blue-emitting BaMgAl(10)O(17):Eu(2+) and yellow-emitting Sr(8)MgY(PO(4))(7):0.01Eu(2+) or Sr(8)MgLa(PO(4))(7):0.03Eu(2+), driven by a 350 mA current. The Sr(8)MgY(PO(4))(7):0.01Eu(2+) and Sr(8)MgLa(PO(4))(7):0.03Eu(2+) containing LEDs produced a white light with Commission International de I'Eclairage (CIE) chromaticity coordinates of (0.348, 0.357) and (0.365, 0.328), warm correlated color temperatures of 4705 and 4100 K, and excellent color rendering indices of 95.375 and 91.75, respectively. PMID:21591766

  2. Color Rendering Plasmonic Aluminum Substrates with Angular Symmetry Breaking.

    PubMed

    Duempelmann, Luc; Casari, Daniele; Luu-Dinh, Angélique; Gallinet, Benjamin; Novotny, Lukas

    2015-12-22

    We fabricate and characterize large-area plasmonic substrates that feature asymmetric periodic nanostructures made of aluminum. Strong coupling between localized and propagating plasmon resonances leads to characteristic Fano line shapes with tunable spectral positions and widths. Distinctive colors spanning the entire visible spectrum are generated by tuning the system parameters, such as the period and the length of the aluminum structures. Moreover, the asymmetry of the aluminum structures gives rise to a strong symmetry broken color rendering effect, for which colors are observed only from one side of the surface normal. Using a combination of immersed laser interference lithography and nanoimprint lithography, our color rendering structures can be fabricated on areas many inches in size. We foresee applications in anticounterfeiting, photovoltaics, sensing, displays, and optical security. PMID:26498131

  3. Facile Atmospheric Pressure Synthesis of High Thermal Stability and Narrow-Band Red-Emitting SrLiAl3N4:Eu(2+) Phosphor for High Color Rendering Index White Light-Emitting Diodes.

    PubMed

    Zhang, Xuejie; Tsai, Yi-Ting; Wu, Shin-Mou; Lin, Yin-Chih; Lee, Jyh-Fu; Sheu, Hwo-Shuenn; Cheng, Bing-Ming; Liu, Ru-Shi

    2016-08-01

    Red phosphors (e.g., SrLiAl3N4:Eu(2+)) with high thermal stability and narrow-band properties are urgently explored to meet the next-generation high-power white light-emitting diodes (LEDs). However, to date, synthesis of such phosphors remains an arduous task. Herein, we report, for the first time, a facile method to synthesize SrLiAl3N4:Eu(2+) through Sr3N2, Li3N, Al, and EuN under atmospheric pressure. The as-synthesized narrow-band red-emitting phosphor exhibits excellent thermal stability, including small chromaticity shift and low thermal quenching. Intriguingly, the title phosphor shows an anomalous increase in theoretical lumen equivalent with the increase of temperature as a result of blue shift and band broadening of the emission band, which is crucial for high-power white LEDs. Utilizing the title phosphor, commercial YAG:Ce(3+), and InGaN-based blue LED chip, a proof-of-concept warm white LEDs with a color rendering index (CRI) of 91.1 and R9 = 68 is achieved. Therefore, our results highlight that this method, which is based on atmospheric pressure synthesis, may open a new means to explore narrow-band-emitting nitride phosphor. In addition, the underlying requirements to design Eu(2+)-doped narrow-band-emitting phosphors were also summarized. PMID:27403812

  4. Ce-doped YAG nanophosphor and red emitting CuInS2/ZnS core/shell quantum dots for warm white light-emitting diode with high color rendering index.

    PubMed

    Aboulaich, Abdelhay; Michalska, Martyna; Schneider, Raphaël; Potdevin, Audrey; Deschamps, Jérôme; Deloncle, Rodolphe; Chadeyron, Geneviève; Mahiou, Rachid

    2014-01-01

    In this work, we report the solvothermal synthesis of Ce-doped YAG (YAG:Ce) nanoparticles (NPs) and their association with a free-Cd CuInS2/ZnS (CIS/ZnS) core/shell QDs for application into white light emitting diode (WLED). 1500 °C-annealed YAG:Ce NPs and CIS/ZnS core/shell QDs exhibited intense yellow and red emissions band with maxima at 545 and 667 nm, respectively. Both YAG:Ce nanophosphor and CIS/ZnS QDs showed high photoluminescence quantum yield (PL QY) of about 50% upon 460 nm excitation. YAG:Ce nanophosphor layer and bilayered YAG:Ce nanophosphor-CIS/ZnS QDs were applied on blue InGaN chip as converter wavelength to achieve WLED. While YAG:Ce nanophosphor converter layer showed low color rendering index (CRI) and cold white light, bilayered YAG:Ce nanophosphor-CIS/ZnS QDs displayed higher CRI of about 84 and warm white light with a correlated color temperature (CCT) of 2784 K. WLED characteristics were measured as a function of forward current from 20 to 1200 mA. The white light stability of bilayered nanophosphor-QDs-based WLED operated at 200 mA was also studied as a function of operating time up to 40 h. Interestingly, CRI and CCT of such device tend to remain constant after 7 h of operating time suggesting that layer-by-layer structure of YAG:Ce phosphor and red-emitting CIS/ZnS QDs could be a good solution to achieve stable warm WLED, especially when high current density is applied. PMID:24320991

  5. Adaptive color rendering of maps for users with color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Kvitle, Anne Kristin; Green, Phil; Nussbaum, Peter

    2015-01-01

    A map is an information design object for which canonical colors for the most common elements are well established. For a CVD observer, it may be difficult to discriminate between such elements - for example, it may be hard to distinguish a red road from a green landscape on the basis of color alone. We address this problem through an adaptive color schema in which the conspicuity of elements in a map to the individual user is maximized. This paper outlines a method to perform adaptive color rendering of map information for users with color vision deficiencies. The palette selection method is based on a pseudo-color palette generation technique which constrains colors to those which lie on the boundary of a reference object color gamut. A user performs a color vision discrimination task, and based on the results of the test, a palette of colors is selected using the pseudo-color palette generation method. This ensures that the perceived difference between palette elements is high but which retains the canonical color of well-known elements as far as possible. We show examples of color palettes computed for a selection of normal and CVD observers, together with maps rendered using these palettes.

  6. Bright three-band white light generated from CdSe/ZnSe quantum dot-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode with high color rendering index

    SciTech Connect

    Jang, Ho Seong; Kwon, Byoung-Hwa; Jeon, Duk Young; Yang, Heesun

    2009-10-19

    In this study, bright three-band white light was generated from the CdSe/ZnSe quantum dot (QD)-assisted Sr{sub 3}SiO{sub 5}:Ce{sup 3+},Li{sup +}-based white light-emitting diode (WLED). The CdSe/ZnSe core/shell structure was confirmed by energy dispersive x-ray spectroscopy and x-ray photoelectron spectroscopy. The CdSe/ZnSe QDs showed high quantum efficiency (79%) and contributed to the high luminous efficiency ({eta}{sub L}) of the fabricated WLED. The WLED showed bright natural white with excellent color rendering property ({eta}{sub L}=26.8 lm/W, color temperature=6140 K, and color rendering index=85) and high stability against the increase in forward bias currents from 20 to 70 mA.

  7. Accurate chromatic control and color rendering optimization in LED lighting systems using junction temperature feedback

    NASA Astrophysics Data System (ADS)

    Sisto, Marco Michele; Gauvin, Jonny

    2014-09-01

    Accurate color control of LED lighting systems is a challenging task: noticeable chromaticity shifts are commonly observed in mixed-color and phosphor converted LEDs due to intensity dimming. Furthermore, the emitted color varies with the LED temperature. We present a novel color control method for tri-chromatic and tetra-chromatic LEDs, which enable to set and maintain the LED emission at a target color, or combination of correlated color temperature (CCT) and intensity. The LED color point is maintained over variations in the LED junctions' temperatures and intensity dimming levels. The method does not require color feedback sensors, so to minimize system complexity and cost, but relies on estimation of the LED junctions' temperatures from the junction voltages. If operated with tetra-chromatic LEDs, the method allows meeting an additional optimization criterion: for example, the maximization of a color rendering metric like the Color Rendering Index (CRI) or the Color Quality Scale (CQS), thus providing a high quality and clarity of colors on the surface illuminated by the LED. We demonstrate the control of a RGBW LED at target D65 white point with CIELAB color difference metric triangle;a,bE < 1 for simultaneous variations of flux from approximately 30 lm to 100 lm and LED heat sink temperature from 25°C to 58°C. In the same conditions, we demonstrate a CCT error <1%. Furthermore, the method allows varying the LED CCT from 5500K to 8000K while maintaining luminance within 1% of target. Further work is ongoing to evaluate the stability of the method over LED aging.

  8. Image indexing using color correlograms

    DOEpatents

    Huang, Jing; Kumar, Shanmugasundaram Ravi; Mitra, Mandar; Zhu, Wei-Jing

    2001-01-01

    A color correlogram is a three-dimensional table indexed by color and distance between pixels which expresses how the spatial correlation of color changes with distance in a stored image. The color correlogram may be used to distinguish an image from other images in a database. To create a color correlogram, the colors in the image are quantized into m color values, c.sub.i . . . c.sub.m. Also, the distance values k.epsilon.[d] to be used in the correlogram are determined where [d] is the set of distances between pixels in the image, and where dmax is the maximum distance measurement between pixels in the image. Each entry (i, j, k) in the table is the probability of finding a pixel of color c.sub.i at a selected distance k from a pixel of color c.sub.i. A color autocorrelogram, which is a restricted version of the color correlogram that considers color pairs of the form (i,i) only, may also be used to identify an image.

  9. Changing the color of textiles with realistic visual rendering

    NASA Astrophysics Data System (ADS)

    Hébert, Mathieu; Henckens, Lambert; Barbier, Justine; Leboulleux, Lucie; Page, Marine; Roujas, Lucie; Cazier, Anthony

    2015-03-01

    Fast and easy preview of a fabric without having to produce samples would be very profitable for textile designers, but remains a technological challenge. As a first step towards this objective, we study the possibility of making images of a real sample, and changing virtually the colors of its yarns while preserving the shine and shadow texture. We consider two types of fabrics: Jacquard weave fabrics made of polyester warp and weft yarns of different colors, and satin ribbons made of polyester and metallic yarns. For the Jacquard fabric, we make a color picture with a scanner on a sample in which the yarns have contrasted colors, threshold this image in order to distinguish the pixels corresponding to each yarn, and accordingly modify their hue and chroma values. This method is simple to operate but do not enable to simulate the angle-dependent shine. A second method, tested on the satin ribbon made of black polyester and achromatic metallic yarns, is based on polarized imaging. We analyze the polarization state of the reflected light which is different for dielectric and metallic materials illuminated by polarized light. We then add a fixed color value to the pixels representing the polyester yarns and modify the hue and chroma of the pixels representing the metallic yarns. This was performed for many incident angles of light, in order to render the twinkling effect displayed by these ribbons. We could verify through a few samples that the simulated previews reproduce real pictures with visually acceptable accuracy.

  10. Spectral optimization of color temperature tunable white LEDs with excellent color rendering and luminous efficacy.

    PubMed

    He, Guoxing; Tang, Ju

    2014-10-01

    The optimization model of limited luminous efficacy (LLE) for correlated color temperature (CCT) tunable phosphor-coated white light-emitting diodes (pc-W LEDs) consisting of blue chips, green and yellow phosphors, and red chips, including downconversion energy loss, has been developed under the constraint of a designated color-rendering index (CRI) and a special CRI of R9 for strong red. The optimal spectra of pc-W LEDs are obtained with a nonlinear program for maximizing LLE under conditions of both CRI and R9 above 90, 95, and 98 at CCTs of 2700-6500 K. The pc-W LEDs with LLE>301  lm/W for both CRI and R9 above 90, LLE>290  lm/W for both CRI and R9 above 95, and LLE>276  lm/W for both CRI and R9 above 98 could be achieved at CCTs of 2700-6500 K. The recommended peak wavelengths and full widths at half-maximum (FWHMs) for the current LEDs and phosphors and their photometric and colorimetric performances are presented. PMID:25360930

  11. Improving color saturation for color managed images rendered using the perceptual intent

    NASA Astrophysics Data System (ADS)

    Marcu, Gabriel G.

    2008-01-01

    In many cases, rendering images using color management approach may result in unsatisfactory color, particularly for cases when the gamut mismatch is large and the source / destination profile pair does not lead to a satisfactory color. This more often the case when images on laptop computer screens with limited color gamut are transferred to print and color management is used. For those cases, we present a method of improving image quality by manipulating the display profile such that the color quality of the printouts is not compromised by the small gamut of the portable display and color management. The basic idea consists of using in the color management pipeline of a virtual gamut that has the role of either the source or of the destination depending on the type of transformation and the gamut size of the source and destination in the color management pipeline. In case the mismatch between the source and destination gamut is under a threshold the virtual gamut is not used. This virtual gamut is constructed directly in the CIE 1931 chromaticity diagram, although other color spaces may be used. A procedure to derive a constant hue line from two adjacent lines is presented. The chromaticities of the virtual gamut are computed based on the replaced gamut chromaticities and a weighting factor computed automatically at the time of rendering. The method proves to give very pleasing results in prints for example and the boost in saturation approximates very well the color enhancement achieved in silver halide photographic prints even for relatively modest print media.

  12. Using nanoimprint lithography to improve the light extraction efficiency and color rendering of dichromatic white light-emitting diodes.

    PubMed

    Lee, Yang-Chun; Chen, Hsuen-Li; Lu, Chih-Yu; Wu, Hung-Sen; Chou, Yung-Fang; Chen, Szu-Huang

    2015-10-21

    Despite the efficiency of gallium nitride (GaN)-based blue light-emitting diodes (LEDs), the light extraction arising from the packaging of the phosphor remains an important issue when enhancing the performance of dichromatic white LEDs. In this study, we employed a simple, inexpensive nanoimprinting process to increase both the light extraction efficiency and color rendering of dichromatic white LEDs. We employed the rigorous coupled wave approach (RCWA) to optimize the light extraction efficiency of yellow and blue light. We found that the presence of the light extracting structures could also improve the color rendering of the dichromatic white LEDs, due to the different light extraction efficiencies of the textured structures at different wavelengths. After fabricating inverted pyramid structures on the surface of the encapsulation layer, the intensity of the blue light at 455 nm increased by 20%. When we further considered the color rendering and correlated color temperature (CCT), the enhancement of blue light was 15% and that of yellow light was 4%. Meanwhile, the light extraction of the intensity dip near 490 nm was enhanced significantly (by 25%), resulting in an increased dip-intensity of light at 490 nm relative to the intensities of the blue and yellow light. Accordingly, the color rendering index (CRI) of this dichromatic white LED increased from 69 to 73. Because it improved both the light extraction efficiency and color rendering of dichromatic white LEDs, this simple method should be very helpful for enhancing their applications in solid state illumination. PMID:26381707

  13. A two-metric proposal to specify the color-rendering properties of light sources for retail lighting

    NASA Astrophysics Data System (ADS)

    Freyssinier, Jean Paul; Rea, Mark

    2010-08-01

    Lighting plays an important role in supporting retail operations, from attracting customers, to enabling the evaluation of merchandise, to facilitating the completion of the sale. Lighting also contributes to the identity, comfort, and visual quality of a retail store. With the increasing availability and quality of white LEDs, retail lighting specifiers are now considering LED lighting in stores. The color rendering of light sources is a key factor in supporting retail lighting goals and thus influences a light source's acceptance by users and specifiers. However, there is limited information on what consumers' color preferences are, and metrics used to describe the color properties of light sources often are equivocal and fail to predict preference. The color rendering of light sources is described in the industry solely by the color rendering index (CRI), which is only indirectly related to human perception. CRI is intended to characterize the appearance of objects illuminated by the source and is increasingly being challenged because new sources are being developed with increasingly exotic spectral power distributions. This paper discusses how CRI might be augmented to better use it in support of the design objectives for retail merchandising. The proposed guidelines include the use of gamut area index as a complementary metric to CRI for assuring good color rendering.

  14. Spectral optimization of phosphor-conversion light-emitting diodes for ultimate color rendering

    NASA Astrophysics Data System (ADS)

    Žukauskas, A.; Vaicekauskas, R.; Ivanauskas, F.; Vaitkevičius, H.; Shur, M. S.

    2008-08-01

    We apply an optimization scheme based on rendering of all colors of the enhanced Munsell palette to phosphor-conversion (PC) light-emitting diodes (LEDs). This approach yields combinations of peak wavelengths and bandwidths for white PC LEDs with partial and complete conversion that enable lighting with better quality than that obtained using designs based on the standard color-rendering assessment procedure.

  15. Using nanoimprint lithography to improve the light extraction efficiency and color rendering of dichromatic white light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Lee, Yang-Chun; Chen, Hsuen-Li; Lu, Chih-Yu; Wu, Hung-Sen; Chou, Yung-Fang; Chen, Szu-Huang

    2015-10-01

    Despite the efficiency of gallium nitride (GaN)-based blue light-emitting diodes (LEDs), the light extraction arising from the packaging of the phosphor remains an important issue when enhancing the performance of dichromatic white LEDs. In this study, we employed a simple, inexpensive nanoimprinting process to increase both the light extraction efficiency and color rendering of dichromatic white LEDs. We employed the rigorous coupled wave approach (RCWA) to optimize the light extraction efficiency of yellow and blue light. We found that the presence of the light extracting structures could also improve the color rendering of the dichromatic white LEDs, due to the different light extraction efficiencies of the textured structures at different wavelengths. After fabricating inverted pyramid structures on the surface of the encapsulation layer, the intensity of the blue light at 455 nm increased by 20%. When we further considered the color rendering and correlated color temperature (CCT), the enhancement of blue light was 15% and that of yellow light was 4%. Meanwhile, the light extraction of the intensity dip near 490 nm was enhanced significantly (by 25%), resulting in an increased dip-intensity of light at 490 nm relative to the intensities of the blue and yellow light. Accordingly, the color rendering index (CRI) of this dichromatic white LED increased from 69 to 73. Because it improved both the light extraction efficiency and color rendering of dichromatic white LEDs, this simple method should be very helpful for enhancing their applications in solid state illumination.Despite the efficiency of gallium nitride (GaN)-based blue light-emitting diodes (LEDs), the light extraction arising from the packaging of the phosphor remains an important issue when enhancing the performance of dichromatic white LEDs. In this study, we employed a simple, inexpensive nanoimprinting process to increase both the light extraction efficiency and color rendering of dichromatic white

  16. Red-emitting silicon quantum dot phosphors in warm white LEDs with excellent color rendering.

    PubMed

    Tu, Chang-Ching; Hoo, Ji H; Böhringer, Karl F; Lin, Lih Y; Cao, Guozhong

    2014-03-10

    We demonstrate red-emitting silicon quantum dot (SiQD) phosphors as a low-cost and environment-friendly alternative to rare-earth element phosphors or CdSe quantum dots. After surface passivation, the SiQD-phosphors achieve high photoluminescence quantum yield = 51% with 365-nm excitation. The phosphors also have a peak photoluminescence wavelength at 630 nm and a full-width-at-half-maximum of 145 nm. The relatively broadband red emission is ideal for forming the basis of a warm white spectrum. With 365-nm or 405-nm LED pumping and the addition of green- and/or blue-emitting rare-earth element phosphors, warm white LEDs with color rendering index ~95 have been achieved. PMID:24922236

  17. Red-emitting silicon quantum dot phosphors in warm white LEDs with excellent color rendering.

    PubMed

    Tu, Chang-Ching; Hoo, Ji H; Böhringer, Karl F; Lin, Lih Y; Cao, Guozhong

    2014-03-10

    We demonstrate red-emitting silicon quantum dot (SiQD) phosphors as a low-cost and environment-friendly alternative to rare-earth element phosphors or CdSe quantum dots. After surface passivation, the SiQD-phosphors achieve high photoluminescence quantum yield = 51% with 365-nm excitation. The phosphors also have a peak photoluminescence wavelength at 630 nm and a full-width-at-half-maximum of 145 nm. The relatively broadband red emission is ideal for forming the basis of a warm white spectrum. With 365-nm or 405-nm LED pumping and the addition of green- and/or blue-emitting rare-earth element phosphors, warm white LEDs with color rendering index ~95 have been achieved. PMID:24800283

  18. Energy-Efficient, High-Color-Rendering LED Lamps Using Oxyfluoride and Fluoride Phosphors

    SciTech Connect

    Setlur, A.; Radkov, E; Henderson, C; Her, J; Srivastava, A; Karkada, N; Kishore, M; Kumar, N; Aesram, D; et al.

    2010-01-01

    LED lamps using phosphor downconversion can be designed to replace incandescent or halogen sources with a 'warm-white' correlated color temperature (CCT) of 2700-3200 K and a color rendering index (CRI) greater than 90. However, these lamps have efficacies of {approx}70% of standard 'cool-white' LED packages (CCT = 4500-6000 K; CRI = 75-80). In this report, we describe structural and luminescence properties of fluoride and oxyfluoride phosphors, specifically a (Sr,Ca){sub 3}(Al,Si)O{sub 4}(F,O):Ce{sup 3+} yellow-green phosphor and a K{sub 2}TiF{sub 6}:Mn{sup 4+} red phosphor, that can reduce this gap and therefore meet the spectral and efficiency requirements for high-efficacy LED lighting. LED lamps with a warm-white color temperature (3088 K), high CRI (90), and an efficacy of {approx}82 lm/W are demonstrated using these phosphors. This efficacy is {approx}85% of comparable cool-white lamps using typical Y{sub 3}Al{sub 5}O{sub 12}:Ce{sup 3+}-based phosphors, significantly reducing the efficacy gap between warm-white and cool-white LED lamps that use phosphor downconversion.

  19. On ratio-based color indexing.

    PubMed

    Adjeroh, D A; Lee, M C

    2001-01-01

    The color ratio approach to indexing has been found to be robust and effective in indexing image and video databases, in different color spaces, and when using transformed color features, such as those from the Karhunen-Loeve transform (KLT) or the discrete cosine transform (DCT). However, the reason for the superior performance of the color ratio model, especially on different color spaces or with transformed color features has, at best, been speculative. This paper develops a generalized form for the color ratio model, based on which we characterize the general distribution of the color ratios. From the distribution, we present a theory that explains and supports the performance of the color ratio approach in image and video indexing. It is shown that the same theory accounts for its effectiveness in different color spaces and in the transform domain. Some general problems encountered in using the original retinex lightness algorithm, and some other issues specific to ratio-based color indexing are discussed in the light of the theory. Results are presented which show that the proposed theory is supported by empirical evidence. PMID:18249595

  20. High Dynamic Range Image rendering of color in chameleons' camouflage using optical thin films

    NASA Astrophysics Data System (ADS)

    Prusten, Mark

    2008-08-01

    High Dynamic Range Image (HDRI) rendering and animation of color in the camouflage of chameleons is developed utilizing thin film optics. Chameleons are a lizard species, and have the ability to change their skin color. This change in color is an expression of the physical and physiological conditions of the lizard, and plays a part in communication. The different colors that can be produced depending on the species include pink, blue, red, orange, green, black, brown and yellow. The modeling, simulation, and rendering of the color, which their skin incorporates, thin film optical stacks. The skin of a chameleon has four layers, which together produce various colors. The outside transparent layer has chromatophores cells, of two kinds of color, yellow and red. Next there are two more layers that reflect light: one blue and the other white. The innermost layer contains dark pigment granules or melanophore cells that influences the amount of reflected light. All of these pigment cells can rapidly relocate their pigments, thereby influencing the color of the chameleon. Techniques like subsurface scattering, the simulation of volumetric scattering of light underneath the objects surface, and final gathering are defined in custom shaders and material phenomena for the renderer. The workflow developed to model the chameleon's skin is also applied to simulation and rendering of hair and fur camouflage, which does not exist in nature.

  1. Near-ultraviolet LED of the External Quantum Efficiency Over 45% and its Application to High-color Rendering Phosphor Conversion White LEDs

    NASA Astrophysics Data System (ADS)

    Sakuta, Hiroaki; Fukui, Takeshi; Miyachi, Tsutomu; Kamon, Kunihito; Hayashi, Hideki; Nakamura, Nobutaka; Uchida, Yuji; Kurai, Satoshi; Taguchi, Tsunemasa

    Highly luminous efficiency and color rendering index (CRI) of 70 lm/W and 95 under low correlated color temperature (CCT) of 3177 K has been obtained by phosphor conversion (PC) white light-emitting diodes (LEDs) using near-ultra violet (n-UV) LEDs with the external quantum efficiency (EQE) of 46.7%. The homogeneous spatial color uniformity on chromaticity of PC white LEDs excited by n-UV LEDs are particularly adequate to the general lighting applications.

  2. Accelerating Time-Varying Hardware Volume Rendering Using TSP Trees and Color-Based Error Metrics

    NASA Technical Reports Server (NTRS)

    Ellsworth, David; Chiang, Ling-Jen; Shen, Han-Wei; Kwak, Dochan (Technical Monitor)

    2000-01-01

    This paper describes a new hardware volume rendering algorithm for time-varying data. The algorithm uses the Time-Space Partitioning (TSP) tree data structure to identify regions within the data that have spatial or temporal coherence. By using this coherence, the rendering algorithm can improve performance when the volume data is larger than the texture memory capacity by decreasing the amount of textures required. This coherence can also allow improved speed by appropriately rendering flat-shaded polygons instead of textured polygons, and by not rendering transparent regions. To reduce the polygonization overhead caused by the use of the hierarchical data structure, we introduce an optimization method using polygon templates. The paper also introduces new color-based error metrics, which more accurately identify coherent regions compared to the earlier scalar-based metrics. By showing experimental results from runs using different data sets and error metrics, we demonstrate that the new methods give substantial improvements in volume rendering performance.

  3. Ammonium hydroxide modulated synthesis of high-quality fluorescent carbon dots for white LEDs with excellent color rendering properties.

    PubMed

    Wang, Shengda; Zhu, Zhifeng; Chang, Yajing; Wang, Hui; Yuan, Nan; Li, Guopeng; Yu, Dabin; Jiang, Yang

    2016-07-22

    A novel type of aqueous fluorescent carbon dot (CD) was synthesized using citric acid as the only carbon source via an ammonium hydroxide modulated method, providing a blue color gamut. The amino group is considered to be the key factor in the high fluorescence of CDs and a model is established to investigate the mechanism of fluorescence. In addition, white light-emitting diodes (WLEDs) are fabricated by utilizing the prepared CDs and rare earth luminescent materials (SrSi2O2N2:Eu and Sr2Si5N8:Eu) as color conversion layers and UV-LED chips as the excitation light source. The WLEDs produce bright white light with attractive color rendering properties including a color rendering index of up to 95.1, a CIE coordinate of (0.33, 0.37), and a T c of 5447 K under a 100 mA driven current, indicating that the CDs are promising in the field of optoelectronic devices. PMID:27276359

  4. Ammonium hydroxide modulated synthesis of high-quality fluorescent carbon dots for white LEDs with excellent color rendering properties

    NASA Astrophysics Data System (ADS)

    Wang, Shengda; Zhu, Zhifeng; Chang, Yajing; Wang, Hui; Yuan, Nan; Li, Guopeng; Yu, Dabin; Jiang, Yang

    2016-07-01

    A novel type of aqueous fluorescent carbon dot (CD) was synthesized using citric acid as the only carbon source via an ammonium hydroxide modulated method, providing a blue color gamut. The amino group is considered to be the key factor in the high fluorescence of CDs and a model is established to investigate the mechanism of fluorescence. In addition, white light-emitting diodes (WLEDs) are fabricated by utilizing the prepared CDs and rare earth luminescent materials (SrSi2O2N2:Eu and Sr2Si5N8:Eu) as color conversion layers and UV-LED chips as the excitation light source. The WLEDs produce bright white light with attractive color rendering properties including a color rendering index of up to 95.1, a CIE coordinate of (0.33, 0.37), and a T c of 5447 K under a 100 mA driven current, indicating that the CDs are promising in the field of optoelectronic devices.

  5. Fabrication of LED lighting goggle for surgical operation and approach toward high-color rendering performance

    NASA Astrophysics Data System (ADS)

    Kawakami, Yoichi; Shimada, Junichi; Fujita, Shigeo

    2001-12-01

    The first internal shunt operation in the left forearm has successfully been performed using the surgical lighting goggle composed of InGaN-yttrium aluminum garnet (YAG)-based white light emitting diode(LED) arrays. This system supplies a total luminous flux of about 200 lumen for several hours by driving with rechargeable Li-ion batteries. Further increase in luminous flux can be achieved by both the progress of emission efficiency of white LEDs and the development of dense packaging technique of LED chips. Moreover, the color rendering properties of white LEDs are inferior to the standard illuminant especially in violet, green and red spectral range. In this paper, several device structures are proposed for achieving power lighting and for higher color rendering properties. The key technology for power lighting is how to radiate the heat out of LED chips, and that for higher color rendering is how to add desired illumination-spectral-components to LEDs according to the application fields.

  6. High color-rendering warm-white lamps using quantum-dot color conversion films.

    PubMed

    Lien, Jiun-Yi; Chen, Chih-Jung; Chiang, Ray-Kuang; Wang, Sue-Lein

    2016-07-11

    Colloidal quantum dots are promising next-generation phosphors to enhance the color rendition of light-emitting diodes (LEDs) while minimizing the brightness droop. In order to exploit the beneficial tunability of quantum dots for highly efficient devices, optimization and determination of the performance limit are of crucial importance. In this work, a facile preparation process of red-emission quantum dot films and simulation algorithm for fitting this film with two commercial LED flat lamps to the optimized performance are developed. Based on the algorithm, one lamp improves from cold-white light (8669 K) with poor color rendition (Ra = 72) and luminous efficacy (85 lm/W) to warm-white light (2867 K) with Ra = 90.8 and R9 = 74.9, and the other reaches Ra = 93 ∼ 95. Impressively, the brightness droop is only about 15 ∼ 20% and the luminous efficacy of 68 lm/W is achieved. Furthermore, our device shows reliability over 1000 hours with only PET (polyethylene-terephthalate) films as the barrier, indicating that this auxiliary red-emission film can be easily applied to improve the color rendition of most commercial LED flat lamps. PMID:27410891

  7. High color-rendering warm-white lamps using quantum-dot color conversion films

    NASA Astrophysics Data System (ADS)

    Lien, Jiun-Yi; Chen, Chih-Jung; Chiang, Ray-Kuang; Wang, Sue-Lein

    2016-07-01

    Colloidal quantum dots are promising next-generation phosphors to enhance the color rendition of light-emitting devices (LEDs) while minimizing the brightness drop. In order to exploit the beneficial tunability of quantum dots for highly efficient devices, optimization and determination of the performance limit are of crucial importance. In this work, a facile preparation process of red-emission quantum dot films and simulation algorithm for fitting this film with two commercial LED flat lamps to the optimized performance are developed. Based on the algorithm, one lamp improves from cold-white light (8669 K) with poor color rendition ($R_{a}=72$) and luminous efficacy (85 lm/W) to warm-white light (2867 K) with $R_{a}=90.8$ and $R_{9}=74.9$, and the other reaches $R_{a}=93\\sim95$. Impressively, the brightness drop is only about $15\\sim20\\%$. Furthermore, our device shows reliability over 1000 hours with only PET (polyethylene-terephthalate) films as the barrier, indicating that this auxiliary red-emission film can be easily applied to improve the color rendition of most commercial LED flat lamps.

  8. Study on the correlations between color rendering indices and the spectral power distribution.

    PubMed

    Lin, Yue; Deng, Zhonghua; Guo, Ziquan; Liu, Zhuguang; Lan, Hai; Lu, Yijun; Cao, Yongge

    2014-06-30

    The intrinsic spectrally resolved sensitivity (ISRS) of color rendering indices (CRIs) is investigated by using spectral loss simulations. It is demonstrated that R(a) exhibits large sensitivities around 444, 480, 564, and 622 nm, while for R(9) the sensitivity peaks are around 461, 581 and 630 nm, which all shift slightly with the correlated color temperature. If considering the ISRS as a bridge between the spectral power distribution of LED and its CRI, one could obtain a high CRI by minimizing the deviation between the shapes of the illuminant spectrum and the reference spectrum, both after modulations by the ISRS as a weighting function. This approach, recommended as a guideline for the spectra design aiming at a high CRI, is described and justified in depth via a mathematical model. This method is spectra-oriented and could largely facilitate the spectra design. PMID:24978066

  9. High-color rendering indices performance of glass based phosphor-converted white light-emitting diodes for solid state lighting

    NASA Astrophysics Data System (ADS)

    Tsai, Chun-Chin; Cheng, Wei-Chih; Chen, Guan-Hao; Lee, Yu-Chun; Kuo, Cheng Ta; Cheng, Wood-Hi

    2014-02-01

    The high-temperature operation of glass based phosphor-converted warm-white light-emitting diodes (PC-WWLEDs) is demonstrated. The fabrication and characteristics of low-temperature phosphor (Yollow:Ce:3+:YAG, Greed:Tb3+:YAG, Red:CaAlClSiN3:Eu2+) doped glass applied to high color rendering indices warm-white-light-emitting diodes was presented. In this property is color coordinates (x, y) = (0.32, 0.28), quantum yield (QY) = 55%, color rending index (CRI) =85, correlated color temperature (CCT) =3900K. The result showed the PC-WLEDs maintained good thermal stability at the high temperature operation. The QY decay, CRI attenuation and chromaticity shift in glass and silicone based high-power PC-WLEDs under thermal aging at 150°C and 250°C are also presented and compared. The result indicated that the glass based PC-WLEDs exhibited better thermal stability than the silicone. And the color rendering indices (CRI) glass phosphor may have potential used as a phosphor layer for high-performance and low-cost PCWLEDs used in next-generation indoors solid-state lighting applications.

  10. Modeling a color-rendering operator for high dynamic range images using a cone-response function

    NASA Astrophysics Data System (ADS)

    Choi, Ho-Hyoung; Kim, Gi-Seok; Yun, Byoung-Ju

    2015-09-01

    Tone-mapping operators are the typical algorithms designed to produce visibility and the overall impression of brightness, contrast, and color of high dynamic range (HDR) images on low dynamic range (LDR) display devices. Although several new tone-mapping operators have been proposed in recent years, the results of these operators have not matched those of the psychophysical experiments based on the human visual system. A color-rendering model that is a combination of tone-mapping and cone-response functions using an XYZ tristimulus color space is presented. In the proposed method, the tone-mapping operator produces visibility and the overall impression of brightness, contrast, and color in HDR images when mapped onto relatively LDR devices. The tone-mapping resultant image is obtained using chromatic and achromatic colors to avoid well-known color distortions shown in the conventional methods. The resulting image is then processed with a cone-response function wherein emphasis is placed on human visual perception (HVP). The proposed method covers the mismatch between the actual scene and the rendered image based on HVP. The experimental results show that the proposed method yields an improved color-rendering performance compared to conventional methods.

  11. High color rendering white light-emitting-diode illuminator using the red-emitting Eu(2+)-activated CaZnOS phosphors excited by blue LED.

    PubMed

    Kuo, Te-Wen; Liu, Wei-Ren; Chen, Teng-Ming

    2010-04-12

    A red phosphor CaZnOS:Eu(2+) was synthesized by solid state reaction and has been evaluated as a candidate for white LEDs. For this material, the XRD, PL, PL excitation (PLE) and diffuse reflection spectra have also been investigated. CaZnOS:Eu(2+) reveals a broad absorption band and good color purity. By utilizing a mixture of red-emitting CaZnOS:Eu(2+), green-emitting (Ba,Sr)(2)SiO(4):Eu(2+) and yellow-emitting Y(3)Al(5)O(12):Ce(3+) as light converters, an intense white InGaN-based blue-LED (~460 nm) was fabricated to exhibit a high color-rendering index Ra of 85 at a correlated color temperature of 4870 K. Based on the results, we are currently evaluating the potential application of CaZnOS:Eu(2+) as a red-emitting blue-chip convertible phosphor. PMID:20588664

  12. Chromatic settings and the structural color constancy index.

    PubMed

    Roca-Vila, Jordi; Parraga, C Alejandro; Vanrell, Maria

    2013-01-01

    Color constancy is usually measured by achromatic setting, asymmetric matching, or color naming paradigms, whose results are interpreted in terms of indexes and models that arguably do not capture the full complexity of the phenomenon. Here we propose a new paradigm, chromatic setting, which allows a more comprehensive characterization of color constancy through the measurement of multiple points in color space under immersive adaptation. We demonstrated its feasibility by assessing the consistency of subjects' responses over time. The paradigm was applied to two-dimensional (2-D) Mondrian stimuli under three different illuminants, and the results were used to fit a set of linear color constancy models. The use of multiple colors improved the precision of more complex linear models compared to the popular diagonal model computed from gray. Our results show that a diagonal plus translation matrix that models mechanisms other than cone gain might be best suited to explain the phenomenon. Additionally, we calculated a number of color constancy indices for several points in color space, and our results suggest that interrelations among colors are not as uniform as previously believed. To account for this variability, we developed a new structural color constancy index that takes into account the magnitude and orientation of the chromatic shift in addition to the interrelations among colors and memory effects. PMID:23479473

  13. Spectral estimation from laser scanner data for accurate color rendering of objects

    NASA Astrophysics Data System (ADS)

    Baribeau, Rejean

    2002-06-01

    Estimation methods are studied for the recovery of the spectral reflectance across the visible range from the sensing at just three discrete laser wavelengths. Methods based on principal component analysis and on spline interpolation are judged based on the CIE94 color differences for some reference data sets. These include the Macbeth color checker, the OSA-UCS color charts, some artist pigments, and a collection of miscellaneous surface colors. The optimal three sampling wavelengths are also investigated. It is found that color can be estimated with average accuracy ΔE94 = 2.3 when optimal wavelengths 455 nm, 540 n, and 610 nm are used.

  14. Virtual Exploration and Comparison of Linear Mastoid Drilling Trajectories with True-Color Volume Rendering and the Visible Ear Dataset

    PubMed Central

    KAHRS, Lueder A.; LABADIE, Robert F.

    2015-01-01

    This paper provides instructions for a virtual exploration and self-study of surgical approaches within the temporal bone. Linear drilling trajectories in the sense of keyhole accesses are compared with free true-color rendering techniques to introduce and evaluate new otologic approaches. On the basis of free cyro-histology image data from a temporal bone six different drill canals are presented. Such a virtual method has the potential to be a first step of investigation of new surgical approaches before moving to cadaver testing. PMID:23400159

  15. Effect of phosphor geometry on the luminous efficiency of high-power white light-emitting diodes with excellent color rendering property.

    PubMed

    Won, Yu-Ho; Jang, Ho Seong; Cho, Kyoung Woo; Song, Yong Seon; Jeon, Duk Young; Kwon, Ho Ki

    2009-01-01

    High-power white light-emitting diodes (LEDs) are fabricated by combining blue LEDs and green (Ba,Sr)(2)SiO(4):Eu(2+) and red CaAlSiN(3):Eu(2+) phosphors with varying phosphor geometry. The white LED having separated the phosphor layer by the silicone gel layer between green and red phosphor layers shows superior optical properties. The luminous efficiency (eta(L)) is improved by a decrease of reabsorption of green light by red phosphor owing to a difference among refractive indices. The white LED shows very high eta(L) of 51 lm/W and a high color rendering index of 95 under 350 mA. In addition, improved luminous properties of the white LED including a separated phosphor layer are confirmed via ray-trace simulation. PMID:19109620

  16. Usage of Data-Encoded Web Maps with Client Side Color Rendering for Combined Data Access, Visualization and Modeling Purposes

    NASA Technical Reports Server (NTRS)

    Pliutau, Denis; Prasad, Narashimha S.

    2013-01-01

    Current approaches to satellite observation data storage and distribution implement separate visualization and data access methodologies which often leads to the need in time consuming data ordering and coding for applications requiring both visual representation as well as data handling and modeling capabilities. We describe an approach we implemented for a data-encoded web map service based on storing numerical data within server map tiles and subsequent client side data manipulation and map color rendering. The approach relies on storing data using the lossless compression Portable Network Graphics (PNG) image data format which is natively supported by web-browsers allowing on-the-fly browser rendering and modification of the map tiles. The method is easy to implement using existing software libraries and has the advantage of easy client side map color modifications, as well as spatial subsetting with physical parameter range filtering. This method is demonstrated for the ASTER-GDEM elevation model and selected MODIS data products and represents an alternative to the currently used storage and data access methods. One additional benefit includes providing multiple levels of averaging due to the need in generating map tiles at varying resolutions for various map magnification levels. We suggest that such merged data and mapping approach may be a viable alternative to existing static storage and data access methods for a wide array of combined simulation, data access and visualization purposes.

  17. Warm-white light-emitting diodes integrated with colloidal quantum dots for high luminous efficacy and color rendering: reply to comment

    NASA Astrophysics Data System (ADS)

    Nizamoglu, Sedat; Erdem, Talha; Sun, Xiao Wei; Demir, Hilmi Volkan

    2011-08-01

    The correlated color temperatures and the corresponding color rendering indices calculated using actual experimental data (and not any prediction) in the original Letter [Opt. Lett. 35, 3372 (2010)] are correct. In addition, here the color rendering of our white LEDs integrated with nanocrystal quantum dots (NQDs) is provided for all test samples. Also, a new NQD-LED design with both high luminous efficacy of optical radiation and CRI is presented to have a chromaticity point in the quadrangle stated in the comment Letter [Opt. Lett. 36, 2851 (2011)]. The points made in the original Letter and all the calculation results provided therein are valid.

  18. Volumetric rendering and metrology of spherical gradient refractive index lens imaged by angular scan optical coherence tomography system.

    PubMed

    Yao, Jianing; Thompson, Kevin P; Ma, Bin; Ponting, Michael; Rolland, Jannick P

    2016-08-22

    In this paper, we develop the methodology, including the refraction correction, geometrical thickness correction, coordinate transformation, and layer segmentation algorithms, for 3D rendering and metrology of a layered spherical gradient refractive index (S-GRIN) lens based on the imaging data collected by an angular scan optical coherence tomography (OCT) system. The 3D mapping and rendering enables direct 3D visualization and internal defect inspection of the lens. The metrology provides assessment of the surface geometry, the lens thickness, the radii of curvature of the internal layer interfaces, and the misalignment of the internal S-GRIN distribution with respect to the lens surface. The OCT metrology results identify the manufacturing defects, and enable targeted process development for optimizing the manufacturing parameters. The newly fabricated S-GRIN lenses show up to a 7x spherical aberration reduction that allows a significantly increased utilizable effective aperture. PMID:27557217

  19. Concentric ring phosphor geometry on the luminous efficiency of white-light-emitting diodes with excellent color rendering property.

    PubMed

    Ying, Shang-Ping; Shen, Jian-Yu

    2016-05-01

    This study presents a novel remote phosphor design involving a concentric ring remote phosphor layer in which green and red phosphors are separated. The green and red phosphor rings were separately illuminated by blue light emitted from the light-emitting diode (LED), causing low reabsorption in phosphor-converted LEDs (pcLEDs) using green and red phosphors. The experimental results revealed that the pcLEDs with green and red phosphors showed high color rendering, indicating that the LEDs are suitable for certain medical applications and architectural lighting. Moreover, for given green/red phosphor ratio and weights of the green and red phosphors, the output power and luminous flux of the pcLED with a concentric ring remote phosphor layer were greater than those of the pcLED with a mixed remote phosphor layer. The reduction in the reabsorption of green emission by red phosphor in pcLED with a concentric ring remote phosphor layer was responsible for the high luminous flux and indicated a high correlated color temperature of pcLED. PMID:27128056

  20. Influence of junction temperature on chromaticity and color-rendering properties of trichromatic white-light sources based on light-emitting diodes

    NASA Astrophysics Data System (ADS)

    Chhajed, S.; Xi, Y.; Li, Y.-L.; Gessmann, Th.; Schubert, E. F.

    2005-03-01

    Trichromatic white-light sources based on light-emitting diodes (LEDs) offer a high luminous efficacy of radiation, a broad range of color temperatures and excellent color-rendering properties with color-rendering indices (CRIs) exceeding 85. An analysis of the luminous efficacy and CRI of a trichromatic light source is performed for a very broad range of wavelength combinations. The peak emission wavelength, spectral width, and the output power of LEDs strongly depend on temperature and the dependencies for red, green, and blue LEDs are established. A detailed analysis of the temperature dependence of trichromatic white LED sources reveals that the luminous efficacy decreases, the color temperature increases, the CRI decreases and the chromaticity point shifts towards the blue as the junction temperature increases. A high CRI >80 can be maintained, by adjusting the LED power ratio so that the chromaticity point is conserved.

  1. Dual emissive manganese and copper Co-doped Zn-In-S quantum dots as a single color-converter for high color rendering white-light-emitting diodes.

    PubMed

    Yuan, Xi; Ma, Ruixin; Zhang, Wenjin; Hua, Jie; Meng, Xiangdong; Zhong, Xinhua; Zhang, Jiahua; Zhao, Jialong; Li, Haibo

    2015-04-29

    Novel white light emitting diodes (LEDs) with environmentally friendly dual emissive quantum dots (QDs) as single color-converters are one of the most promising high-quality solid-state lighting sources for meeting the growing global demand for resource sustainability. A facile method was developed for the synthesis of the bright green-red-emitting Mn and Cu codoped Zn-In-S QDs with an absorption bangdgap of 2.56 eV (485 nm), a large Stokes shift of 150 nm, and high emission quantum yield up to 75%, which were suitable for warm white LEDs based on blue GaN chips. The wide photoluminescence (PL) spectra composed of Cu-related green and Mn-related red emissions in the codoped QDs could be controlled by varying the doping concentrations of Mn and Cu ions. The energy transfer processes in Mn and Cu codoped QDs were proposed on the basis of the changes in PL intensity and lifetime measured by means of steady-state and time-resolved PL spectra. By integrating these bicolor QDs with commercial GaN-based blue LEDs, the as-fabricated tricolor white LEDs showed bright natural white light with a color rendering index of 95, luminous efficacy of 73.2 lm/W, and color temperature of 5092 K. These results indicated that (Mn,Cu):Zn-In-S/ZnS QDs could be used as a single color-converting material for the next generation of solid-state lighting. PMID:25866991

  2. Color Index Imaging of the Stellar Stream Around NGC 5907

    NASA Astrophysics Data System (ADS)

    Laine, Seppo; Grillmair, Carl J.; Martinez-Delgado, David; Romanowsky, Aaron J.; Capak, Peter; Arendt, Richard G.; Ashby, Matthew; Davies, James E.; Majewski, Steven R.; GaBany, R. Jay

    2015-01-01

    We have obtained deep g, r, and i-band Subaru and ultra-deep 3.6 micron Spitzer/IRAC images of parts of the stellar stream around the nearby edge-on disk galaxy NGC 5907. We report on the color index distribution of the resolved emission along the stream, and indicators of recent star formation associated with the stream. We present scenarios regarding the nature of the disrupted satellite galaxy, based on our data. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This work is based in part on data collected with the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Support for this work was provided by NASA through an award issued by JPL/Caltech.

  3. Color Index Imaging of the Stellar Stream Around NGC 5907

    NASA Astrophysics Data System (ADS)

    Laine, Seppo; Grillmair, Carl J.; Martinez-Delgado, David; Romanowsky, Aaron; Capak, Peter; Arendt, Richard G.; Ashby, M. L. N.; Davies, James; Majewski, Steven; GaBany, R. Jay

    2015-08-01

    We have obtained deep g, r, and i-band Subaru and ultra-deep 3.6 micron Spitzer/IRAC images of parts of the spectacular, multiply-looped stellar stream around the nearby edge-on disk galaxy NGC 5907. We report on the color index distribution of the integrated starlight and the derived stellar populations along the stream. We present scenarios regarding the nature of the disrupted satellite galaxy, based on our data. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under a contract with NASA. This work is based in part on data collected with the Subaru Telescope, which is operated by the National Astronomical Observatory of Japan. Support for this work was provided by NASA through an award issued by JPL/Caltech.

  4. One-Step Preparation of Blue-Emitting (La,Ca)Si3(O,N)5:Ce3+ Phosphors for High-Color Rendering White Light-Emitting Diodes

    NASA Astrophysics Data System (ADS)

    Yaguchi, Atsuro; Suehiro, Takayuki; Sato, Tsugio; Hirosaki, Naoto

    2011-02-01

    Highly phase-pure (La,Ca)Si3(O,N)5:Ce3+ blue-emitting phosphors were successfully synthesized via the one-step solid-state reaction from the system La2O3-CaO-CeO2-Si3N4. The synthesized (La,Ca)Si3(O,N)5:Ce3+ exhibits tunable blue broadband emission with the dominant wavelength of 466-479 nm and the external quantum efficiency up to ˜45% under 380 nm near-UV (NUV) excitation. Spectral simulations of the trichromatic white light-emitting diodes (LEDs) using (La,Ca)Si3(O,N)5:Ce3+ demonstrated markedly higher color rendering index Ra values of 93-95, compared to 76-90 attained by the systems using a conventional BAM:Eu2+ phosphor or InGaN blue LED. The present achievement indicates the promising applicability of (La,Ca)Si3(O,N)5:Ce3+ as a blue luminescent source for NUV-converting high-color rendering white LEDs.

  5. Evaluation of the effectiveness of color attributes for video indexing

    NASA Astrophysics Data System (ADS)

    Chupeau, Bertrand; Forest, Ronan

    2001-10-01

    Color features are reviewed and their effectiveness assessed in the application framework of key-frame clustering for abstracting unconstrained video. Existing color spaces and associated quantization schemes are first studied. Description of global color distribution by means of histograms is then detailed. In our work, 12 combinations of color space and quantization were selected, together with 12 histogram metrics. Their respective effectiveness with respect to picture similarity measurement was evaluated through a query-by-example scenario. For that purpose, a set of still-picture databases was built by extracting key frames from several video clips, including news, documentaries, sports and cartoons. Classical retrieval performance evaluation criteria were adapted to the specificity of our testing methodology.

  6. Evaluation of the effectiveness of color attributes for video indexing

    NASA Astrophysics Data System (ADS)

    Chupeau, Bertrand; Forest, Ronan

    2000-12-01

    Color features are reviewed and their effectiveness assessed in the application framework of key-frame clustering for abstracting unconstrained video. Existing color spaces and associated quantization schemes are first studied. Description of global color distribution by means of histograms is then detailed. In our work, twelve combinations of color space and quantization were selected, together with twelve histogram metrics. Their respective effectiveness with respect to picture similarity measurement was evaluated through a query-be-example scenario. For that purpose, a set of still-picture databases was built by extracting key-frames from several video clips, including news, documentaries, sports and cartoons. Classical retrieval performance evaluation criteria were adapted to the specificity of our testing methodology.

  7. Evaluation of the effectiveness of color attributes for video indexing

    NASA Astrophysics Data System (ADS)

    Chupeau, Bertrand; Forest, Ronan

    2001-01-01

    Color features are reviewed and their effectiveness assessed in the application framework of key-frame clustering for abstracting unconstrained video. Existing color spaces and associated quantization schemes are first studied. Description of global color distribution by means of histograms is then detailed. In our work, twelve combinations of color space and quantization were selected, together with twelve histogram metrics. Their respective effectiveness with respect to picture similarity measurement was evaluated through a query-be-example scenario. For that purpose, a set of still-picture databases was built by extracting key-frames from several video clips, including news, documentaries, sports and cartoons. Classical retrieval performance evaluation criteria were adapted to the specificity of our testing methodology.

  8. SRTM Data Release for Eurasia, Index Map and Colored Height

    NASA Technical Reports Server (NTRS)

    2004-01-01

    , various landforms place constraints upon land use planning for a great population. Volcanoes in the East Indies, the Philippines, Japan, and the Kamchatka Peninsula form the western part of the 'Ring of Fire' around the Pacific Ocean.

    Many of these regions were previously very poorly mapped due to persistent cloud cover or the inaccessibility of the terrain. Digital elevation data, such as provided by SRTM, are particularly in high demand by scientists studying earthquakes, volcanism, and erosion patterns for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there, so elevation data are used in a wide range of applications.

    In this index map color-coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations. The large, very dark green feature in western Asia is the Caspian Sea, which is below sea level. Blue areas on the map represent water within the mapped tiles, each of which includes shorelines or islands.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion

  9. SRTM Data Release for Eurasia, Index Map and Colored Height

    NASA Technical Reports Server (NTRS)

    2004-01-01

    , various landforms place constraints upon land use planning for a great population. Volcanoes in the East Indies, the Philippines, Japan, and the Kamchatka Peninsula form the western part of the 'Ring of Fire' around the Pacific Ocean.

    Many of these regions were previously very poorly mapped due to persistent cloud cover or the inaccessibility of the terrain. Digital elevation data, such as provided by SRTM, are particularly in high demand by scientists studying earthquakes, volcanism, and erosion patterns for use in mapping and modeling hazards to human habitation. But the shape of Earth's surface affects nearly every natural process and human endeavor that occurs there, so elevation data are used in a wide range of applications.

    In this index map color-coding is directly related to topographic height, with green at the lower elevations, rising through yellow and tan, to white at the highest elevations. The large, very dark green feature in western Asia is the Caspian Sea, which is below sea level. Blue areas on the map represent water within the mapped tiles, each of which includes shorelines or islands.

    Elevation data used in this image was acquired by the Shuttle Radar Topography Mission (SRTM) aboard the Space Shuttle Endeavour, launched on February 11, 2000. SRTM used the same radar instrument that comprised the Spaceborne Imaging Radar-C/X-Band Synthetic Aperture Radar (SIR-C/X-SAR) that flew twice on the Space Shuttle Endeavour in 1994. SRTM was designed to collect three-dimensional measurements of the Earth's surface. To collect the 3-D data, engineers added a 60-meter-long (200-foot) mast, installed additional C-band and X-band antennas, and improved tracking and navigation devices. The mission is a cooperative project between the National Aeronautics and Space Administration (NASA), the National Geospatial-Intelligence Agency (NGA) of the U.S. Department of Defense (DoD), and the German and Italian space agencies. It is managed by NASA's Jet Propulsion

  10. Parallel rendering

    NASA Technical Reports Server (NTRS)

    Crockett, Thomas W.

    1995-01-01

    This article provides a broad introduction to the subject of parallel rendering, encompassing both hardware and software systems. The focus is on the underlying concepts and the issues which arise in the design of parallel rendering algorithms and systems. We examine the different types of parallelism and how they can be applied in rendering applications. Concepts from parallel computing, such as data decomposition, task granularity, scalability, and load balancing, are considered in relation to the rendering problem. We also explore concepts from computer graphics, such as coherence and projection, which have a significant impact on the structure of parallel rendering algorithms. Our survey covers a number of practical considerations as well, including the choice of architectural platform, communication and memory requirements, and the problem of image assembly and display. We illustrate the discussion with numerous examples from the parallel rendering literature, representing most of the principal rendering methods currently used in computer graphics.

  11. The site occupation and valence of Mn ions in the crystal lattice of Sr{sub 4}Al{sub 14}O{sub 25} and its deep red emission for high color-rendering white light-emitting diodes

    SciTech Connect

    Chen, Lei; Xue, Shaochan; Chen, Xiuling; Bahader, Ali; Deng, Xiaorong; Zhao, Erlong; Jiang, Yang; Chen, Shifu; Chan, Ting-Shan; Zhao, Zhi; Zhang, Wenhua

    2014-12-15

    Highlights: • Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were identified using XANES and EPR. • Red luminescence was attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. • The Mn{sup 3+} incorporated in the center of AlO{sub 4} tetrahedron was non-luminescent. • The bond-valence theory was used to analyze the effective valences of cations. • A white LED device with CRI up to Ra 93.23 was packaged by using the red phosphor. - Abstract: The synthesis and component of red phosphor, Sr{sub 4}Al{sub 14}O{sub 25}: Mn, were optimized for application in white light-emitting diodes. The microstructure and morphology were investigated by the X-ray diffraction and scanning electron microscopy. Different valences of Mn ions in Sr{sub 4}Al{sub 14}O{sub 25} were discriminated using the electron paramagnetic resonance and X-ray absorption near-edge structure spectroscopy techniques. The bond-valence theory was used to analyze the effective valences of Sr{sup 2+} and Al{sup 3+} in Sr{sub 4}Al{sub 14}O{sub 25}. As a result, the strong covalence of Al{sup 3+} in the AlO{sub 4} tetrahedron other than in the AlO{sub 6} octahedron is disclosed. The deep red emission is attributed to Mn{sup 4+} occupying the center of AlO{sub 6} octahedron. The mechanism of energy transfer is mainly through dipole–dipole interaction, revealed by the analyses of critical distance and concentration quench. A high color rendering white LED prototype with color-rendering index up to Ra 93.23 packaged by using the red phosphor demonstrates its applicability.

  12. Color of kerogen as index of organic maturity

    NASA Technical Reports Server (NTRS)

    Peters, K. E.; Kaplan, I. R.; Ishiwatari, R.

    1977-01-01

    Kerogen from the Tanner basin off southern California was heated under nitrogen at different temperatures and times and subsequently was studied under the transmitted light microscope. Samples darken in color from yellow through shades of brown to black with increasing thermal maturation. The transition from dark brown to very dark brown marks the range of maximum n-alkane generation where the residue attains an atomic H/C of about 0.80 plus or minus 0.05. The apparent activation energy for this transition was about 45 plus or minus 5 kcal per mole.

  13. 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

  14. LETTER TO THE EDITOR: High colour rendering index non-doped-type white organic light-emitting devices with a RGB-stacked multilayer structure

    NASA Astrophysics Data System (ADS)

    Xie, Wenfa; Zhao, Yi; Li, Chuannan; Liu, Shiyong

    2005-12-01

    A non-doped-type white organic light-emitting device with high colour rendering index has been reported. The structure of the device is ITO/NPB (50 nm)/TPBI (3 nm)/Alq3 (d nm)/DCM2 (0.1 nm)/TPBI (40 - d nm)/Alq3 (10 nm)/LiF/Al, where NPB is N, N'-bis-(1-naphthyl)-N, N'-diphenyl-1, 1'-biph-enyl-4, 4'-diamine, TPBI is 2, 2', 2''-(1, 3, 5-phenylene) tris(1-phenyl-1H-benzimidazole), Alq3 is tris (8-hydroxyquinoline) aluminium, DCM2 is [2-methyl-6-[2-(2, 3, 6, 7-tetrahydro-1H, 5H-benzo[ij] quinolizin-9-yl)ethenyl]-4H-pyran-4-ylidene] propane-dinitrile. Through the optimization of d, pure white emission with CIE coordinates of (0.3198, 0.3400) at 9 V was obtained, at which the colour temperature and colour rendering index were 6080 K and 97, respectively. The CIE coordinates of the device change from (0.4552, 0.3867) at 4 V to (0.2864, 0.2865) at 19 V that are well in the white region. Its maximum luminance was 10 855 cd m-2 at 19 V and maximum power efficiency was 1.31 lm W-1 at 5 V.

  15. Quantum rendering

    NASA Astrophysics Data System (ADS)

    Lanzagorta, Marco O.; Gomez, Richard B.; Uhlmann, Jeffrey K.

    2003-08-01

    In recent years, computer graphics has emerged as a critical component of the scientific and engineering process, and it is recognized as an important computer science research area. Computer graphics are extensively used for a variety of aerospace and defense training systems and by Hollywood's special effects companies. All these applications require the computer graphics systems to produce high quality renderings of extremely large data sets in short periods of time. Much research has been done in "classical computing" toward the development of efficient methods and techniques to reduce the rendering time required for large datasets. Quantum Computing's unique algorithmic features offer the possibility of speeding up some of the known rendering algorithms currently used in computer graphics. In this paper we discuss possible implementations of quantum rendering algorithms. In particular, we concentrate on the implementation of Grover's quantum search algorithm for Z-buffering, ray-tracing, radiosity, and scene management techniques. We also compare the theoretical performance between the classical and quantum versions of the algorithms.

  16. Index theorem and Majorana zero modes along a non-Abelian vortex in a color superconductor

    SciTech Connect

    Fujiwara, Takanori; Fukui, Takahiro; Nitta, Muneto; Yasui, Shigehiro

    2011-10-01

    Color superconductivity in high-density QCD exhibits the color-flavor-locked phase. To explore zero modes in the color-flavor-locked phase in the presence of a non-Abelian vortex with an SU(2) symmetry in the vortex core, we apply the index theorem to the Bogoliubov-de Gennes (BdG) Hamiltonian. From the calculation of the topological index, we find that triplet, doublet and singlet sectors of SU(2) have certain number of chiral Majorana zero modes in the limit of vanishing chemical potential. We also solve the BdG equation by the use of the series expansion to show that the number of zero modes and their chirality match the result of the index theorem. From particle-hole symmetry of the BdG Hamiltonian, we conclude that if and only if the index of a given sector is odd, one zero mode survives generically for a finite chemical potential. We argue that this result should hold nonperturbatively even in the high-density limit.

  17. Color-coding Improves Parental Understanding of Body Mass Index Charting

    PubMed Central

    Oettinger, Matthew D.; Finkle, Joanne P.; Esserman, Denise; Whitehead, Lisa; Spain, Thomas K.; Pattishall, Steven R.; Rothman, Russell; Perrin, Eliana M.

    2009-01-01

    Objectives To assess parental understanding of body mass index (BMI) and BMI percentiles using standard versus color-coded charts and investigate how parental literacy and/or numeracy (quantitative skills) impacts that understanding. Methods A convenience sample of 163 parents of children aged 2–8 years at two academic pediatric centers completed a demographics questionnaire, the mathematics portion of the Wide Range Achievement Test (WRAT-3R), the Short Test of Functional Health Literacy in Adults (S-TOFHLA), and an “Understanding BMI” questionnaire, which included parallel BMI charting questions to compare understanding of standard versus color-coded BMI charting. Outcomes included parental-reported versus actual understanding of BMI, the odds (obtained by generalized estimating equations) of answering parallel questions correctly using standard versus color-coded charting, and odds of answering questions correctly based on numeracy and literacy. Results Many parents (60%) reported knowing what BMI was, but only 30% could define it even roughly correctly. Parents using color-coded charts had greater odds of answering parallel BMI charting questions correctly than parents using standard charts (mean 88% vs. 65% correct; pooled AOR=4.32, 95% CI: 3.14–5.95; p<.01). Additionally, parents with lower numeracy (K-5 level) benefited more from color-coded charts (increased from 51% to 81% correct) than did higher numeracy parents (≥ high school level), who performed well using both charts (89% vs. 99% correct). Conclusions Parents consistently performed better using color-coded than standard BMI charts. Color-coding was particularly helpful for lower numeracy parents. Future studies should investigate whether these results translate into offices and whether understanding motivates parents toward important lifestyle change. PMID:19679524

  18. Color applied to printing graphic design: the importance of lighting in the color perception and specification process

    NASA Astrophysics Data System (ADS)

    Goncalves, Berenice S.; Pereira, Alice C.; Pereira, Fernando R.

    2002-06-01

    This work approaches the importance of lighting in the process of chromatic categorization, selection and specification applied to the printed media. Some concepts regarding lighting are presented, such as color temperature, color appearance and color rendering index. Finally, stands out the necessity to evaluate the samples under standard lighting conditions regarding the environment where the final product will be exposed.

  19. A survey on palette reordering methods for improving the compression of color-indexed images.

    PubMed

    Pinho, Armando J; Neves, António J R

    2004-11-01

    Palette reordering is a well-known and very effective approach for improving the compression of color-indexed images. In this paper, we provide a survey of palette reordering methods, and we give experimental results comparing the ability of seven of them in improving the compression efficiency of JPEG-LS and lossless JPEG 2000. We concluded that the pairwise merging heuristic proposed by Memon et al. is the most effective, but also the most computationally demanding. Moreover, we found that the second most effective method is a modified version of Zeng's reordering technique, which was 3%-5% worse than pairwise merging, but much faster. PMID:15540450

  20. Spectral reflectance of conodonts: A step toward quantitative color alteration and thermal maturity indexes

    SciTech Connect

    Deaton, B.C.; Nestell, M.; Balsam, W.L.

    1996-07-01

    Changes in the color of conodonts have long been used to assess thermal maturity. Color is a subjective measure, and color changes in conodonts are related to a subjective scale, the conodont alteration index or CAI. In this paper, we propose a simple, nondestructive method for objectively determining CAI and relating CAI to thermal maturity, the spectral reflectance of conodonts (SRC). The diffuse reflectance of about 30 large conodont fragments arranged on a barium-sulfate slide was determined with a total reflectance spectrophotometer in the wavelength range of 300-850 nm. By examining conodonts that ranged form a CAI of 1 to a CAI of 6 we found that the average slope of the reflectance curve from 550 to 800 nm is a good proxy for CAI. A second-order regression equation estimates CAI from this slope with high accuracy (correlation coefficient = 0.99). These estimates appear most accurate for a CAI of 1 to a CAI of 4, where the slopes change most rapidly, but give reasonable results up to a CAI of 6. Based on the results of our analysis of two samples with known thermal maturities form the Valles Caldera region of New Mexico, we propose a preliminary relationship among SRC slope, CAI, and in-situ alteration temperature.

  1. NONLINEAR COLOR-METALLICITY RELATIONS OF GLOBULAR CLUSTERS. V. NONLINEAR ABSORPTION-LINE INDEX VERSUS METALLICITY RELATIONS AND BIMODAL INDEX DISTRIBUTIONS OF M31 GLOBULAR CLUSTERS

    SciTech Connect

    Kim, Sooyoung; Yoon, Suk-Jin; Chung, Chul; Lee, Young-Wook; Caldwell, Nelson; Schiavon, Ricardo P.; Kang, Yongbeom; Rey, Soo-Chang

    2013-05-10

    Recent spectroscopy on the globular cluster (GC) system of M31 with unprecedented precision witnessed a clear bimodality in absorption-line index distributions of old GCs. Such division of extragalactic GCs, so far asserted mainly by photometric color bimodality, has been viewed as the presence of merely two distinct metallicity subgroups within individual galaxies and forms a critical backbone of various galaxy formation theories. Given that spectroscopy is a more detailed probe into stellar population than photometry, the discovery of index bimodality may point to the very existence of dual GC populations. However, here we show that the observed spectroscopic dichotomy of M31 GCs emerges due to the nonlinear nature of metallicity-to-index conversion and thus one does not necessarily have to invoke two separate GC subsystems. We take this as a close analogy to the recent view that metallicity-color nonlinearity is primarily responsible for observed GC color bimodality. We also demonstrate that the metallicity-sensitive magnesium line displays non-negligible metallicity-index nonlinearity and Balmer lines show rather strong nonlinearity. This gives rise to bimodal index distributions, which are routinely interpreted as bimodal metallicity distributions, not considering metallicity-index nonlinearity. Our findings give a new insight into the constitution of M31's GC system, which could change much of the current thought on the formation of GC systems and their host galaxies.

  2. Interference color modulation, tunable refractive index, and chiroptical electrochromism in a π-conjugated polymer with cholesteric liquid crystal order

    NASA Astrophysics Data System (ADS)

    Goto, Hiromasa

    2009-06-01

    A π-conjugated polymer film prepared by electrolytic polymerization using a cholesteric liquid crystal (CLC) is demonstrated to have a tunable interference function under electrochemical doping and dedoping. The polymer exhibits a CLC-like periodic structure with a potential-dependent refractive index and optical absorption properties. The interference color of the polymer film can thus be modulated dynamically by appropriate application of a voltage in the ±1 V range. This research involves structural chirality and tunable chiroptical properties, doping-dedoping driven tunable refractive index, electrochromism, and interference color modulation for the present polymer. The phenomena demonstrate the possibility of electrochemical photonics.

  3. Color Photographic Index of Fall Chinook Salmon Embryonic Development and Accumulated Thermal Units

    PubMed Central

    Boyd, James W.; Oldenburg, Eric W.; McMichael, Geoffrey A.

    2010-01-01

    Background Knowledge of the relationship between accumulated thermal units and developmental stages of Chinook salmon embryos can be used to determine the approximate date of egg fertilization in natural redds, thus providing insight into oviposition timing of wild salmonids. However, few studies have documented time to different developmental stages of embryonic Chinook salmon and no reference color photographs are available. The objectives of this study were to construct an index relating developmental stages of hatchery-reared fall Chinook salmon embryos to time and temperature (e.g., degree days) and provide high-quality color photographs of each identified developmental stage. Methodology/Principal Findings Fall Chinook salmon eggs were fertilized in a hatchery environment and sampled approximately every 72 h post-fertilization until 50% hatch. Known embryonic developmental features described for sockeye salmon were used to describe development of Chinook salmon embryos. A thermal sums model was used to describe the relationship between embryonic development rate and water temperature. Mean water temperature was 8.0°C (range; 3.9–11.7°C) during the study period. Nineteen stages of embryonic development were identified for fall Chinook salmon; two stages in the cleavage phase, one stage in the gastrulation phase, and sixteen stages in the organogenesis phase. The thermal sums model used in this study provided similar estimates of fall Chinook salmon embryonic development rate in water temperatures varying from 3.9–11.7°C (mean = 8°C) to those from several other studies rearing embryos in constant 8°C water temperature. Conclusions/Significance The developmental index provides a reasonable description of timing to known developmental stages of Chinook salmon embryos and was useful in determining developmental stages of wild fall Chinook salmon embryos excavated from redds in the Columbia River. This index should prove useful to other researchers who

  4. [Research on developping the spectral dataset for Dunhuang typical colors based on color constancy].

    PubMed

    Liu, Qiang; Wan, Xiao-Xia; Liu, Zhen; Li, Chan; Liang, Jin-Xing

    2013-11-01

    The present paper aims at developping a method to reasonably set up the typical spectral color dataset for different kinds of Chinese cultural heritage in color rendering process. The world famous wall paintings dating from more than 1700 years ago in Dunhuang Mogao Grottoes was taken as typical case in this research. In order to maintain the color constancy during the color rendering workflow of Dunhuang culture relics, a chromatic adaptation based method for developping the spectral dataset of typical colors for those wall paintings was proposed from the view point of human vision perception ability. Under the help and guidance of researchers in the art-research institution and protection-research institution of Dunhuang Academy and according to the existing research achievement of Dunhuang Research in the past years, 48 typical known Dunhuang pigments were chosen and 240 representative color samples were made with reflective spectral ranging from 360 to 750 nm was acquired by a spectrometer. In order to find the typical colors of the above mentioned color samples, the original dataset was devided into several subgroups by clustering analysis. The grouping number, together with the most typical samples for each subgroup which made up the firstly built typical color dataset, was determined by wilcoxon signed rank test according to the color inconstancy index comprehensively calculated under 6 typical illuminating conditions. Considering the completeness of gamut of Dunhuang wall paintings, 8 complementary colors was determined and finally the typical spectral color dataset was built up which contains 100 representative spectral colors. The analytical calculating results show that the median color inconstancy index of the built dataset in 99% confidence level by wilcoxon signed rank test was 3.28 and the 100 colors are distributing in the whole gamut uniformly, which ensures that this dataset can provide reasonable reference for choosing the color with highest

  5. Space weathering and the color indexes of minor bodies in the outer Solar System

    NASA Astrophysics Data System (ADS)

    Kaňuchová, Z.; Brunetto, R.; Melita, M.; Strazzulla, G.

    2012-09-01

    We present a model based on laboratory results which contributes to the "nature" versus "nurture" debate on the colors of small bodies in the outer Solar System (OSS). According to our model, objects having suffered the same balance of irradiation and impacts follow specific curves in color-color diagrams. Appropriate combination of composition and weathering can reproduce the whole range of colors observed on OSS small bodies

  6. Conodont color alteration index and upper Paleozoic thermal history of the Amazonas Basin, Brazil

    NASA Astrophysics Data System (ADS)

    Cardoso, Cassiane Negreiros; Sanz-López, Javier; Blanco-Ferrera, Silvia; Lemos, Valesca Brasil; Scomazzon, Ana Karina

    2015-12-01

    The conodont color alteration index (CAI) was determined in elements from core samples of the Frasnian Barreirinha Formation (one well) and of the Pennsylvanian-Permian Tapajós Group (twenty three wells and one limestone quarry) in the Amazonas Basin. The thermal history of the basin is analyzed using the CAI value distribution represented in maps and stratigraphic sections through correlation schemes, and in conjunction with previously published data. The pattern of palaeotemperatures for CAI values of 1.5-3 is coincident with organic matter maturation under a sedimentary overburden providing diagenetic conditions in the oil/gas window. Locally, conodonts show metamorphism (CAI value of 6-7) in relation to the intrusion of diabase bodies in beds including high geothermal gradient evaporites. Microtextural alteration on the surface conodonts commonly shows several types of overgrowth microtextures developed in diagenetic conditions. Locally, recrystallization in conodonts with a high CAI value is congruent with contact metamorphism in relation to Mesozoic intrusions. The CAI values of 1.5 or 2 observed close to the surface in several areas of the basin may be interpreted in relation to a high thermal palaeogradient derived from the magmatic episode or/and to the local denudation of the upper part of the Paleozoic succession prior to this thermal event.

  7. High color rending index and high-efficiency white organic light-emitting diodes based on the control of red phosphorescent dye-doped hole transport layer.

    PubMed

    Zhang, M Y; Wang, F F; Wei, N; Zhou, P C; Peng, K J; Yu, J N; Wang, Z X; Wei, B

    2013-01-14

    We have investigated the transport characteristics of red phosphorescent dye bis(1-(phenyl)isoquinoline) iridium (III) acetylanetonate (Ir(piq)₂acac) doped 4,4',4"-tri(N-carbazolyl)triphenylamine (TCTA), and found that the increasing doping ratio was facilitated to improve the ability of hole transporting. A high color rendering index (CRI) and high-efficiency WOLED was achieved by employing Ir(piq)₂acac doped TCTA film as an effective red emissive layer due to the generation of charge transfer complex (CTC) at the interface. The relative proportion in red: green: blue emission intensity can be controlled by the CTC concentration to obtain high CRI WOLEDs. The WOLED with an optimal red dye doping concentration of 5 wt% exhibits a high CRI of 89 and a power efficiency of 31.2 lm/W and 27.5 lm/W at the initial luminance and 100 cd/m², respectively. The devices show little variation of the Commission Internationale de I'Eclairage coordinates in a wide range of luminance. PMID:23389269

  8. Acquisition of Digital Color-Infrared Photographs for Monitoring Leaf Area Index of Winter Wheat

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Aerial color-infrared photography has the high spatial resolution required for assessing within-field variability of crop growth. We describe a new method for acquiring digital color-infrared photographs for monitoring vegetation on the ground or from Unmanned Airborne Vehicles (UAVs). A red-block...

  9. Space weathering and the color indexes of minor bodies in the outer Solar System

    NASA Astrophysics Data System (ADS)

    Kaňuchová, Zuzana; Brunetto, Rosario; Melita, Mario; Strazzulla, Giovanni

    2012-09-01

    The surfaces of small bodies in the outer Solar System are rich in organic compounds and carbonaceous refractories mixed with ices and silicates. As made clear by dedicated laboratory experiments space weathering (e.g. energetic ion bombardment) can produce red colored materials starting from bright and spectrally flat ices. In a classical scenario, the space weathering processes “nurture” alter the small bodies surface spectra but are in competition with resurfacing agents that restore the original colors, and the result of these competing processes continuously modifying the surfaces is supposed to be responsible for the observed spectral variety of those small bodies. However an alternative point of view is that the different colors are due to “nature” i.e. to the different primordial composition of different objects. In this paper we present a model, based on laboratory results, that gives an original contribution to the “nature” vs. “nurture” debate by addressing the case of surfaces showing different fractions of rejuvenated vs. space weathered surface, and calculating the corresponding color variations. We will show how a combination of increasing dose coupled to different resurfacing can reproduce the whole range of observations of small outer Solar System bodies. Here we demonstrate, for the first time that objects having a fully weathered material turn back in the color-color diagrams. At the same time, object with the different ratio of pristine and weathered surface areas lay on specific lines in color-color diagrams, if exposed to the same amount of irradiation.

  10. Lifetime Reduction and Enhanced Emission of Single Photon Color Centers in Nanodiamond via Surrounding Refractive Index Modification

    PubMed Central

    Khalid, Asma; Chung, Kelvin; Rajasekharan, Ranjith; Lau, Desmond W.M.; Karle, Timothy J.; Gibson, Brant C.; Tomljenovic-Hanic, Snjezana

    2015-01-01

    The negatively-charged nitrogen vacancy (NV−) center in diamond is of great interest for quantum information processing and quantum key distribution applications due to its highly desirable long coherence times at room temperature. One of the challenges for their use in these applications involves the requirement to further optimize the lifetime and emission properties of the centers. Our results demonstrate the reduction of the lifetime of NV− centers, and hence an increase in the emission rate, achieved by modifying the refractive index of the environment surrounding the nanodiamond (ND). By coating the NDs in a polymer film, experimental results and numerical calculations show an average of 63% reduction in the lifetime and an average enhancement in the emission rate by a factor of 1.6. This strategy is also applicable for emitters other than diamond color centers where the particle refractive index is greater than the refractive index of the surrounding media. PMID:26109500

  11. Lifetime Reduction and Enhanced Emission of Single Photon Color Centers in Nanodiamond via Surrounding Refractive Index Modification

    NASA Astrophysics Data System (ADS)

    Khalid, Asma; Chung, Kelvin; Rajasekharan, Ranjith; Lau, Desmond W. M.; Karle, Timothy J.; Gibson, Brant C.; Tomljenovic-Hanic, Snjezana

    2015-06-01

    The negatively-charged nitrogen vacancy (NV-) center in diamond is of great interest for quantum information processing and quantum key distribution applications due to its highly desirable long coherence times at room temperature. One of the challenges for their use in these applications involves the requirement to further optimize the lifetime and emission properties of the centers. Our results demonstrate the reduction of the lifetime of NV- centers, and hence an increase in the emission rate, achieved by modifying the refractive index of the environment surrounding the nanodiamond (ND). By coating the NDs in a polymer film, experimental results and numerical calculations show an average of 63% reduction in the lifetime and an average enhancement in the emission rate by a factor of 1.6. This strategy is also applicable for emitters other than diamond color centers where the particle refractive index is greater than the refractive index of the surrounding media.

  12. North Atlantic Plio-Pliestocene sediment color climate index indicates enhanced 41-k.y. world variability

    NASA Astrophysics Data System (ADS)

    Obrochta, Stephen; Bailey, Ian; Channell, James; Hodell, David; Timmermann, Axel; Tyler, Jonathan; Xuan, Chuang; Yokoyama, Yusuke

    2016-04-01

    Sediment color variations at North Atlantic Site DSDP609/U1308 exhibit a very similar pattern to the water isotope record of the North GRIP ice core. Moving window cross correlation between NGRIP oxygen isotopes and sediment lightness (L*) reveals a consistently high and significant correlation. Based on this relationship, we construct a color-based climate index by calculating color reflectance values from the shipboard line-scanner images. Use of the line-scanner images provides a higher-resolution series (0.01 cm) than the 2-cm shipboard spectrophotometer data and permits for manual removal of disturbed pixels prior to analysis. At present, the composite benthic oxygen isotope and paleomagnetic records at Site U1308 extend to MIS K2, providing age control beyond 3 Ma. The same approach at a more northerly location (IODP Site U1304) yields very similar results, in terms of event pattern, timing, and duration, over the past few glacial cycles, suggesting the much longer Site U1308 record likely reflects conditions over a relatively large spatial area. Rapidity of color variations decreases following the onset of the large amplitude 100-k.y. glaciations. Both Sites U1304 and U1308 exhibit near identical color changes during the penultimate glaciation (MIS 6), which is characterized by fluctuations that are among the most gradual of the entire ~3 Ma record. With the exception of MIS 6, results generally agree with the synthetic Greenland isotope record. Orbital scale color variations are near synchronous with benthic oxygen isotopes at a 41 k.y. period but lag significantly at 100 k.y.

  13. High-accuracy self-correction of refractive index of air using two-color interferometry of optical frequency combs.

    PubMed

    Minoshima, Kaoru; Arai, Kaoru; Inaba, Hajime

    2011-12-19

    Long-path pulse-to-pulse interferometers of two-color frequency combs are developed using fundamental and second harmonics of a mode-locked fiber laser. Interferometric phase difference between two-color frequency combs was precisely measured by stabilizing the fundamental fringe phase by controlling the repetition frequency of the comb, and a stability of 10(-10) for 1000 s was achieved in the measurement of an optical path length difference between two wavelengths. In long-term measurements performed for 10 h, results of phase variation of interferometric measurements were highly consistent with the fluctuations in the calculated difference of refractive indices of air at two wavelengths with an accuracy of 10(-10). The difference between the measured optical distances corresponding to two wavelengths and the optical distance corresponding to the fundamental wavelength were used in the two-color method; high-accuracy self-correction of the fluctuation of refractive index of air was performed with an uncertainty of 5 × 10(-8) for 10-h measurements when the maximum refractive index change was on the order of 10(-6). PMID:22274198

  14. Parallel sphere rendering

    SciTech Connect

    Krogh, M.; Painter, J.; Hansen, C.

    1996-10-01

    Sphere rendering is an important method for visualizing molecular dynamics data. This paper presents a parallel algorithm that is almost 90 times faster than current graphics workstations. To render extremely large data sets and large images, the algorithm uses the MIMD features of the supercomputers to divide up the data, render independent partial images, and then finally composite the multiple partial images using an optimal method. The algorithm and performance results are presented for the CM-5 and the M.

  15. 10 CFR Appendix R to Subpart B of... - Uniform Test Method for Measuring Average Lamp Efficacy (LE), Color Rendering Index (CRI), and...

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Lamps 4.3.1The measurement procedure shall be as described in IESNA LM-20 (see 10 CFR 430.22). Lamps... characterization shall be conducted in accordance with the methods given in IESNA LM-58 and IESNA LM-16 (see 10 CFR... appropriate reference ballast at input voltage specified by the reference circuit as described in ANSI...

  16. 10 CFR Appendix R to Subpart B of... - Uniform Test Method for Measuring Average Lamp Efficacy (LE), Color Rendering Index (CRI), and...

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... Lamps 4.3.1 The measurement procedure shall be as described in IESNA LM-20 (see 10 CFR 430.22). Lamps... reference circuit as described in ANSI C82.3 (incorporated by reference; see § 430.3). If, for a lamp,...

  17. 10 CFR Appendix R to Subpart B of... - Uniform Test Method for Measuring Average Lamp Efficacy (LE), Color Rendering Index (CRI), and...

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... Lamps 4.3.1The measurement procedure shall be as described in IESNA LM-20 (see 10 CFR 430.22). Lamps... characterization shall be conducted in accordance with the methods given in IESNA LM-58 and IESNA LM-16 (see 10 CFR... appropriate reference ballast at input voltage specified by the reference circuit as described in ANSI...

  18. 10 CFR Appendix R to Subpart B of... - Uniform Test Method for Measuring Average Lamp Efficacy (LE), Color Rendering Index (CRI), and...

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... Lamps 4.3.1 The measurement procedure shall be as described in IESNA LM-20 (see 10 CFR 430.22). Lamps... reference circuit as described in ANSI C82.3 (incorporated by reference; see § 430.3). If, for a lamp,...

  19. 10 CFR Appendix R to Subpart B of... - Uniform Test Method for Measuring Average Lamp Efficacy (LE), Color Rendering Index (CRI), and...

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... Lamps 4.3.1The measurement procedure shall be as described in IESNA LM-20 (see 10 CFR 430.22). Lamps... characterization shall be conducted in accordance with the methods given in IESNA LM-58 and IESNA LM-16 (see 10 CFR... appropriate reference ballast at input voltage specified by the reference circuit as described in ANSI...

  20. Integration of Color and Local Derivative Pattern Features for Content-Based Image Indexing and Retrieval

    NASA Astrophysics Data System (ADS)

    Vipparthi, Santosh Kumar; Nagar, Shyam Krishna

    2014-09-01

    This paper presents two new feature descriptors for content based image retrieval (CBIR) application. The proposed two descriptors are named as color local derivative patterns (CLDP) and inter color local derivative pattern (ICLDP). In order to reduce the computational complexity the uniform patterns are applied to both CLDP and ICLDP. Further, uniform CLDP (CLDPu2) and uniform ICLDP (ICLDPu2) are generated respectively. The proposed descriptors are able to exploit individual (R, G and B) spectral channel information and co-relating pair (RG, GB, BR, etc.) of spectral channel information. The retrieval performances of the proposed descriptors (CLDP and ICLDP) are tested by conducting two experiments on Corel-5000 and Corel-10000 benchmark databases. The results after investigation show a significant improvement in terms of precision, average retrieval precision (ARP), recall and average retrieval rate (ARR) as compared to local binary patterns (LBP), local derivative patterns (LDP) and other state-of-the-art techniques for image retrieval.

  1. Integration of Color and Local Derivative Pattern Features for Content-Based Image Indexing and Retrieval

    NASA Astrophysics Data System (ADS)

    Vipparthi, Santosh Kumar; Nagar, Shyam Krishna

    2015-09-01

    This paper presents two new feature descriptors for content based image retrieval (CBIR) application. The proposed two descriptors are named as color local derivative patterns (CLDP) and inter color local derivative pattern (ICLDP). In order to reduce the computational complexity the uniform patterns are applied to both CLDP and ICLDP. Further, uniform CLDP (CLDPu2) and uniform ICLDP (ICLDPu2) are generated respectively. The proposed descriptors are able to exploit individual (R, G and B) spectral channel information and co-relating pair (RG, GB, BR, etc.) of spectral channel information. The retrieval performances of the proposed descriptors (CLDP and ICLDP) are tested by conducting two experiments on Corel-5000 and Corel-10000 benchmark databases. The results after investigation show a significant improvement in terms of precision, average retrieval precision (ARP), recall and average retrieval rate (ARR) as compared to local binary patterns (LBP), local derivative patterns (LDP) and other state-of-the-art techniques for image retrieval.

  2. Multivariate volume rendering

    SciTech Connect

    Crawfis, R.A.

    1996-03-01

    This paper presents a new technique for representing multivalued data sets defined on an integer lattice. It extends the state-of-the-art in volume rendering to include nonhomogeneous volume representations. That is, volume rendering of materials with very fine detail (e.g. translucent granite) within a voxel. Multivariate volume rendering is achieved by introducing controlled amounts of noise within the volume representation. Varying the local amount of noise within the volume is used to represent a separate scalar variable. The technique can also be used in image synthesis to create more realistic clouds and fog.

  3. Parallel sphere rendering

    SciTech Connect

    Krogh, M.; Hansen, C.; Painter, J.; de Verdiere, G.C.

    1995-05-01

    Sphere rendering is an important method for visualizing molecular dynamics data. This paper presents a parallel divide-and-conquer algorithm that is almost 90 times faster than current graphics workstations. To render extremely large data sets and large images, the algorithm uses the MIMD features of the supercomputers to divide up the data, render independent partial images, and then finally composite the multiple partial images using an optimal method. The algorithm and performance results are presented for the CM-5 and the T3D.

  4. Sorting and hardware assisted rendering for volume visualization

    SciTech Connect

    Stein, C.; Becker, B.; Max, N.

    1994-03-01

    We present some techniques for volume rendering unstructured data. Interpolation between vertex colors and opacities is performed using hardware assisted texture mapping, and color is integrated for use with a volume rendering system. We also present an O(n{sup 2}) method for sorting n arbitrarily shaped convex polyhedra prior to visualization. It generalizes the Newell, Newell and Sancha sort for polygons to 3-D volume elements.

  5. A practical approach to spectral volume rendering.

    PubMed

    Bergner, Steven; Möller, Torsten; Tory, Melanie; Drew, Mark S

    2005-01-01

    To make a spectral representation of color practicable for volume rendering, a new low-dimensional subspace method is used to act as the carrier of spectral information. With that model, spectral light material interaction can be integrated into existing volume rendering methods at almost no penalty. In addition, slow rendering methods can profit from the new technique of postillumination-generating spectral images in real-time for arbitrary light spectra under a fixed viewpoint. Thus, the capability of spectral rendering to create distinct impressions of a scene under different lighting conditions is established as a method of real-time interaction. Although we use an achromatic opacity in our rendering, we show how spectral rendering permits different data set features to be emphasized or hidden as long as they have not been entirely obscured. The use of postillumination is an order of magnitude faster than changing the transfer function and repeating the projection step. To put the user in control of the spectral visualization, we devise a new widget, a "light-dial," for interactively changing the illumination and include a usability study of this new light space exploration tool. Applied to spectral transfer functions, different lights bring out or hide specific qualities of the data. In conjunction with postillumination, this provides a new means for preparing data for visualization and forms a new degree of freedom for guided exploration of volumetric data sets. PMID:15747643

  6. Ghostscript color management

    NASA Astrophysics Data System (ADS)

    Vrhel, Michael J.; Johnston, Raymond

    2011-01-01

    This document introduces an updated color architecture that has been designed for Ghostscript. Ghostscript is a well known open source document rendering and conversion engine. Prior to this update, the handling of color in Ghostscript was based primarily upon PostScript color management. The new design results in a flexible ICC-based architecture that works well in Ghostscript's multi-threaded rendering environment.

  7. Method and apparatus for enhanced evanescent fluorescence and color filtering using a high refractive index thin film coating

    DOEpatents

    Kao, Hung Pin; Schoeniger, Joseph; Yang, Nancy

    2001-01-01

    A technique for increasing the excitation and collection of evanescent fluorescence radiation emanating from a fiber optic sensor having a high refractive index (n.sub.r), dielectric thin film coating has been disclosed and described. The invention comprises a clad optical fiber core whose cladding is removed on a distal end, the distal end coated with a thin, non-porous, titanium dioxide sol-gel coating. It has been shown that such a fiber will exhibit increased fluorescence coupling due in part by 1) increasing the intensity of the evanescent field at the fiber core surface by a constructive interference effect on the propagating light, and 2) increasing the depth of penetration of the field in the sample. The interference effect created by the thin film imposes a wavelength dependence on the collection of the fluorescence and also suggests a novel application of thin films for color filtering as well as increasing collected fluorescence in fiber sensors. Collected fluorescence radiation increased by up to 6-fold over that of a bare fused silica fiber having a numerical aperture (N.A.) of O.6.

  8. Rendering the Topological Spines

    SciTech Connect

    Nieves-Rivera, D.

    2015-05-05

    Many tools to analyze and represent high dimensional data already exits yet most of them are not flexible, informative and intuitive enough to help the scientists make the corresponding analysis and predictions, understand the structure and complexity of scientific data, get a complete picture of it and explore a greater number of hypotheses. With this in mind, N-Dimensional Data Analysis and Visualization (ND²AV) is being developed to serve as an interactive visual analysis platform with the purpose of coupling together a number of these existing tools that range from statistics, machine learning, and data mining, with new techniques, in particular with new visualization approaches. My task is to create the rendering and implementation of a new concept called topological spines in order to extend ND²AV's scope. Other existing visualization tools create a representation preserving either the topological properties or the structural (geometric) ones because it is challenging to preserve them both simultaneously. Overcoming such challenge by creating a balance in between them, the topological spines are introduced as a new approach that aims to preserve them both. Its render using OpenGL and C++ and is currently being tested to further on be implemented on ND²AV. In this paper I will present what are the Topological Spines and how they are rendered.

  9. Using color management in color document processing

    NASA Astrophysics Data System (ADS)

    Nehab, Smadar

    1995-04-01

    Color Management Systems have been used for several years in Desktop Publishing (DTP) environments. While this development hasn't matured yet, we are already experiencing the next generation of the color imaging revolution-Device Independent Color for the small office/home office (SOHO) environment. Though there are still open technical issues with device independent color matching, they are not the focal point of this paper. This paper discusses two new and crucial aspects in using color management in color document processing: the management of color objects and their associated color rendering methods; a proposal for a precedence order and handshaking protocol among the various software components involved in color document processing. As color peripherals become affordable to the SOHO market, color management also becomes a prerequisite for common document authoring applications such as word processors. The first color management solutions were oriented towards DTP environments whose requirements were largely different. For example, DTP documents are image-centric, as opposed to SOHO documents that are text and charts centric. To achieve optimal reproduction on low-cost SOHO peripherals, it is critical that different color rendering methods are used for the different document object types. The first challenge in using color management of color document processing is the association of rendering methods with object types. As a result of an evolutionary process, color matching solutions are now available as application software, as driver embedded software and as operating system extensions. Consequently, document processing faces a new challenge, the correct selection of the color matching solution while avoiding duplicate color corrections.

  10. 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.

  11. Vector quantization for volume rendering

    NASA Technical Reports Server (NTRS)

    Ning, Paul; Hesselink, Lambertus

    1992-01-01

    Volume rendering techniques typically process volumetric data in raw, uncompressed form. As algorithmic and architectural advances improve rendering speeds, however, larger data sets will be evaluated requiring consideration of data storage and transmission issues. In this paper, we analyze the data compression requirements for volume rendering applications and present a solution based on vector quantization. The proposed system compresses volumetric data and then renders images directly from the new data format. Tests on a fluid flow data set demonstrate that good image quality may be achieved at a compression ratio of 17:1 with only a 5 percent cost in additional rendering time.

  12. Enriching text with images and colored light

    NASA Astrophysics Data System (ADS)

    Sekulovski, Dragan; Geleijnse, Gijs; Kater, Bram; Korst, Jan; Pauws, Steffen; Clout, Ramon

    2008-01-01

    We present an unsupervised method to enrich textual applications with relevant images and colors. The images are collected by querying large image repositories and subsequently the colors are computed using image processing. A prototype system based on this method is presented where the method is applied to song lyrics. In combination with a lyrics synchronization algorithm the system produces a rich multimedia experience. In order to identify terms within the text that may be associated with images and colors, we select noun phrases using a part of speech tagger. Large image repositories are queried with these terms. Per term representative colors are extracted using the collected images. Hereto, we either use a histogram-based or a mean shift-based algorithm. The representative color extraction uses the non-uniform distribution of the colors found in the large repositories. The images that are ranked best by the search engine are displayed on a screen, while the extracted representative colors are rendered on controllable lighting devices in the living room. We evaluate our method by comparing the computed colors to standard color representations of a set of English color terms. A second evaluation focuses on the distance in color between a queried term in English and its translation in a foreign language. Based on results from three sets of terms, a measure of suitability of a term for color extraction based on KL Divergence is proposed. Finally, we compare the performance of the algorithm using either the automatically indexed repository of Google Images and the manually annotated Flickr.com. Based on the results of these experiments, we conclude that using the presented method we can compute the relevant color for a term using a large image repository and image processing.

  13. Software for Acoustic Rendering

    NASA Technical Reports Server (NTRS)

    Miller, Joel D.

    2003-01-01

    SLAB is a software system that can be run on a personal computer to simulate an acoustic environment in real time. SLAB was developed to enable computational experimentation in which one can exert low-level control over a variety of signal-processing parameters, related to spatialization, for conducting psychoacoustic studies. Among the parameters that can be manipulated are the number and position of reflections, the fidelity (that is, the number of taps in finite-impulse-response filters), the system latency, and the update rate of the filters. Another goal in the development of SLAB was to provide an inexpensive means of dynamic synthesis of virtual audio over headphones, without need for special-purpose signal-processing hardware. SLAB has a modular, object-oriented design that affords the flexibility and extensibility needed to accommodate a variety of computational experiments and signal-flow structures. SLAB s spatial renderer has a fixed signal-flow architecture corresponding to a set of parallel signal paths from each source to a listener. This fixed architecture can be regarded as a compromise that optimizes efficiency at the expense of complete flexibility. Such a compromise is necessary, given the design goal of enabling computational psychoacoustic experimentation on inexpensive personal computers.

  14. Sea modeling and rendering

    NASA Astrophysics Data System (ADS)

    Cathala, Thierry; Latger, Jean

    2010-10-01

    More and more defence and civil applications require simulation of marine synthetic environment. Currently, the "Future Anti-Surface-Guided-Weapon" (FASGW) or "anti-navire léger" (ANL) missile needs this kind of modelling. This paper presents a set of technical enhancement of the SE-Workbench that aim at better representing the sea profile and the interaction with targets. The operational scenario variability is a key criterion: the generic geographical area (e.g. Persian Gulf, coast of Somalia,...), the type of situation (e.g. peace keeping, peace enforcement, anti-piracy, drug interdiction,...)., the objectives (political, strategic, or military objectives), the description of the mission(s) (e.g. antipiracy) and operation(s) (e.g. surveillance and reconnaissance, escort, convoying) to achieve the objectives, the type of environment (Weather, Time of day, Geography [coastlines, islands, hills/mountains]). The paper insists on several points such as the dual rendering using either ray tracing [and the GP GPU optimization] or rasterization [and GPU shaders optimization], the modelling of sea-surface based on hypertextures and shaders, the wakes modelling, the buoyancy models for targets, the interaction of coast and littoral, the dielectric infrared modelling of water material.

  15. Parallel hierarchical radiosity rendering

    SciTech Connect

    Carter, M.

    1993-07-01

    In this dissertation, the step-by-step development of a scalable parallel hierarchical radiosity renderer is documented. First, a new look is taken at the traditional radiosity equation, and a new form is presented in which the matrix of linear system coefficients is transformed into a symmetric matrix, thereby simplifying the problem and enabling a new solution technique to be applied. Next, the state-of-the-art hierarchical radiosity methods are examined for their suitability to parallel implementation, and scalability. Significant enhancements are also discovered which both improve their theoretical foundations and improve the images they generate. The resultant hierarchical radiosity algorithm is then examined for sources of parallelism, and for an architectural mapping. Several architectural mappings are discussed. A few key algorithmic changes are suggested during the process of making the algorithm parallel. Next, the performance, efficiency, and scalability of the algorithm are analyzed. The dissertation closes with a discussion of several ideas which have the potential to further enhance the hierarchical radiosity method, or provide an entirely new forum for the application of hierarchical methods.

  16. The physics of volume rendering

    NASA Astrophysics Data System (ADS)

    Peters, Thomas

    2014-11-01

    Radiation transfer is an important topic in several physical disciplines, probably most prominently in astrophysics. Computer scientists use radiation transfer, among other things, for the visualization of complex data sets with direct volume rendering. In this article, I point out the connection between physical radiation transfer and volume rendering, and I describe an implementation of direct volume rendering in the astrophysical radiation transfer code RADMC-3D. I show examples for the use of this module on analytical models and simulation data.

  17. Time-Critical Volume Rendering

    NASA Technical Reports Server (NTRS)

    Kaufman, Arie

    1998-01-01

    For the past twelve months, we have conducted and completed a joint research entitled "Time- Critical Volume Rendering" with NASA Ames. As expected, High performance volume rendering algorithms have been developed by exploring some new faster rendering techniques, including object presence acceleration, parallel processing, and hierarchical level-of-detail representation. Using our new techniques, initial experiments have achieved real-time rendering rates of more than 10 frames per second of various 3D data sets with highest resolution. A couple of joint papers and technique reports as well as an interactive real-time demo have been compiled as the result of this project.

  18. 11. Photographic copy of rendering (February 15, 1913, original rendering ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    11. Photographic copy of rendering (February 15, 1913, original rendering in Archives, Public Affairs Department, Sears Merchandise Group, Hoffman Estates, Illinois), Artist unknown. OVERALL VIEW OF MAIL ORDER PLANT, VIEW TO SOUTH - Sears Roebuck & Company Mail Order Plant, Bounded by Lexington & Grenshaw Streets, Kedzie Avenue & Independence Boulevard, Chicago, Cook County, IL

  19. Massively parallel visualization: Parallel rendering

    SciTech Connect

    Hansen, C.D.; Krogh, M.; White, W.

    1995-12-01

    This paper presents rendering algorithms, developed for massively parallel processors (MPPs), for polygonal, spheres, and volumetric data. The polygon algorithm uses a data parallel approach whereas the sphere and volume renderer use a MIMD approach. Implementations for these algorithms are presented for the Thinking Machines Corporation CM-5 MPP.

  20. New Uses for Rendered Protein

    Technology Transfer Automated Retrieval System (TEKTRAN)

    The history of rendering shows that current uses for rendered protein are a result of value-adding research. Feed nutritionists discovered how to use this formerly very low value by-product as an important component of formulated livestock feed. Today the feed market is mature and has been severel...

  1. Progress in characterizing the multidimensional color quality properties of white LED light sources

    NASA Astrophysics Data System (ADS)

    Teunissen, Kees; Hoelen, Christoph

    2016-03-01

    With the introduction of solid state light sources, the variety in emission spectra is almost unlimited. However, the set of standardized parameters to characterize a white LED light source, such as correlated color temperature (CCT) and CIE general color rendering index (Ra), is known to be limited and insufficient for describing perceived differences between light sources. Several characterization methods have been proposed over the past decades, but their contribution to perceived color quality has not always been validated. To gain more insight in the relevant characteristics of the emission spectra for specific applications, we have conducted a perception experiment to rate the attractiveness of three sets of objects, including fresh food, packaging materials and skin tones. The objects were illuminated with seven different combinations of Red, Green, Blue, Amber and White LEDs, all with the same CCT and illumination level, but with differences in Ra and color saturation. The results show that, in general, object attractiveness does not correlate well with Ra, but shows a positive correlation with saturation increase for two out of three applications. There is no clear relation between saturation and skin tone attractiveness, partly due to differences in preference between males and females. A relative gamut area index (Ga) represents the average change in saturation and a complementary color vector graphic shows the direction and magnitude of chromatic differences for the eight CIE-1974 test-color samples. Together with the CIE general color rendering index (Ra) they provide useful information for designing and optimizing application specific emission spectra.

  2. Color M-mode Doppler flow propagation velocity is a preload insensitive index of left ventricular relaxation: animal and human validation

    NASA Technical Reports Server (NTRS)

    Garcia, M. J.; Smedira, N. G.; Greenberg, N. L.; Main, M.; Firstenberg, M. S.; Odabashian, J.; Thomas, J. D.

    2000-01-01

    OBJECTIVES: To determine the effect of preload in color M-mode Doppler flow propagation velocity (v(p)). BACKGROUND: The interpretation of Doppler filling patterns is limited by confounding effects of left ventricular (LV) relaxation and preload. Color M-mode v(p) has been proposed as a new index of LV relaxation. METHODS: We studied four dogs before and during inferior caval (IVC) occlusion at five different inotropic stages and 14 patients before and during partial cardiopulmonary bypass. Left ventricular (LV) end-diastolic volumes (LV-EDV), the time constant of isovolumic relaxation (tau), left atrial (LA) pre-A and LV end-diastolic pressures (LV-EDP) were measured. Peak velocity during early filling (E) and v(p) were extracted by digital analysis of color M-mode Doppler images. RESULTS: In both animals and humans, LV-EDV and LV-EDP decreased significantly from baseline to IVC occlusion (both p < 0.001). Peak early filling (E) velocity decreased in animals from 56 +/- 21 to 42 +/- 17 cm/s (p < 0.001) without change in v(p) (from 35 +/- 15 to 35 +/- 16, p = 0.99). Results were similar in humans (from 69 +/- 15 to 53 +/- 22 cm/s, p < 0.001, and 37 +/- 12 to 34 +/- 16, p = 0.30). In both species, there was a strong correlation between LV relaxation (tau) and v(p) (r = 0.78, p < 0.001, r = 0.86, p < 0.001). CONCLUSIONS: Our results indicate that color M-mode Doppler v(p) is not affected by preload alterations and confirms that LV relaxation is its main physiologic determinant in both animals during varying lusitropic conditions and in humans with heart disease.

  3. Exposure Render: An Interactive Photo-Realistic Volume Rendering Framework

    PubMed Central

    Kroes, Thomas; Post, Frits H.; Botha, Charl P.

    2012-01-01

    The field of volume visualization has undergone rapid development during the past years, both due to advances in suitable computing hardware and due to the increasing availability of large volume datasets. Recent work has focused on increasing the visual realism in Direct Volume Rendering (DVR) by integrating a number of visually plausible but often effect-specific rendering techniques, for instance modeling of light occlusion and depth of field. Besides yielding more attractive renderings, especially the more realistic lighting has a positive effect on perceptual tasks. Although these new rendering techniques yield impressive results, they exhibit limitations in terms of their exibility and their performance. Monte Carlo ray tracing (MCRT), coupled with physically based light transport, is the de-facto standard for synthesizing highly realistic images in the graphics domain, although usually not from volumetric data. Due to the stochastic sampling of MCRT algorithms, numerous effects can be achieved in a relatively straight-forward fashion. For this reason, we have developed a practical framework that applies MCRT techniques also to direct volume rendering (DVR). With this work, we demonstrate that a host of realistic effects, including physically based lighting, can be simulated in a generic and flexible fashion, leading to interactive DVR with improved realism. In the hope that this improved approach to DVR will see more use in practice, we have made available our framework under a permissive open source license. PMID:22768292

  4. Color perception under illumination by quadrichromatic solid-state lamp

    NASA Astrophysics Data System (ADS)

    Stanikunas, Rytis; Vaitkevicius, Henrikas; Svegzda, Algimantas; Viliunas, Vilius; Bliznikas, Zenius; Breive, Kestutis; Vaicekauskas, Rimantas; Novickovas, Algirdas; Kurilcik, Genadij; Zukauskas, Arturas; Gaska, Remis; Shur, Michael S.

    2004-10-01

    Lighting based on sources of light composed of colored light-emitting diodes (LEDs) offers versatile control of color and a possibility of trade-off between efficiency and color rendering. However, psychophysical issues related to such polychromatic solid-state sources have to be addressed. In this work, studies of the perception of standard colors under illumination with a quadrichromatic red-amber-green-blue (RAGB) solid-state source were carried out. An RAGB lamp containing primary LEDs with the emission peaks at 638 nm, 594 nm, 523 nm, and 441 nm and optimized for the highest value of the general color rendering index (86 points) was investigated and compared to a tungsten lamp. 40 standard Munsell samples of value 6, chroma /6, and hue incremented by 2.5 were used in the investigation. Changes in the saturation and hue of the Munsell samples illuminated by the RAGB lamp versus tungsten lamp (both with the correlated temperature of 2600 K) were obtained by colorimetric calculation comparisons and by psychophysical experiments on subjective matching of the samples. Subjective differences in hue and subjective color discrimination differences under the tungsten and RAGB lamps were found in the wavelength range of 440-500 nm and 560-580 nm. We attribute these differences to non-optimal peak wavelengths of the primary LEDs and to the narrow-band components of the RAGB spectrum.

  5. Scalable rendering on PC clusters

    SciTech Connect

    WYLIE,BRIAN N.; LEWIS,VASILY; SHIRLEY,DAVID NOYES; PAVLAKOS,CONSTANTINE

    2000-04-25

    This case study presents initial results from research targeted at the development of cost-effective scalable visualization and rendering technologies. The implementations of two 3D graphics libraries based on the popular sort-last and sort-middle parallel rendering techniques are discussed. An important goal of these implementations is to provide scalable rendering capability for extremely large datasets (>> 5 million polygons). Applications can use these libraries for either run-time visualization, by linking to an existing parallel simulation, or for traditional post-processing by linking to an interactive display program. The use of parallel, hardware-accelerated rendering on commodity hardware is leveraged to achieve high performance. Current performance results show that, using current hardware (a small 16-node cluster), they can utilize up to 85% of the aggregate graphics performance and achieve rendering rates in excess of 20 million polygons/second using OpenGL{reg_sign} with lighting, Gouraud shading, and individually specified triangles (not t-stripped).

  6. Efficient volume rendering using octree space subdivision

    NASA Astrophysics Data System (ADS)

    Krumhauer, Peter; Tsygankov, Michael; Reich, Christian; Evgrafov, Anton

    1999-03-01

    This paper describes a discrete ray-tracing algorithm, which employs the adaptive hierarchical spatial subdivision (octree) technique for 3D uniform binary voxel space representation. The binary voxel space contains voxels of two kinds: 'surface' and 'non-surface.' Surface voxels include property information like the surface normal and color. The usage of octrees dramatically reduces the memory amount required to store 3D models. The average compression ratio is in the range between 1:24 up to 1:50 compared to uncompressed voxels. A fast ray casting algorithm called BOXER was developed, which allows rendering 256 X 256 X 256 and 512 X 512 X 512 volumes nearly in real-time on standard Intel-based PCs.

  7. Fast data parallel polygon rendering

    SciTech Connect

    Ortega, F.A.; Hansen, C.D.

    1993-09-01

    This paper describes a parallel method for polygonal rendering on a massively parallel SIMD machine. This method, based on a simple shading model, is targeted for applications which require very fast polygon rendering for extremely large sets of polygons such as is found in many scientific visualization applications. The algorithms described in this paper are incorporated into a library of 3D graphics routines written for the Connection Machine. The routines are implemented on both the CM-200 and the CM-5. This library enables a scientists to display 3D shaded polygons directly from a parallel machine without the need to transmit huge amounts of data to a post-processing rendering system.

  8. RenderMan design principles

    NASA Technical Reports Server (NTRS)

    Apodaca, Tony; Porter, Tom

    1989-01-01

    The two worlds of interactive graphics and realistic graphics have remained separate. Fast graphics hardware runs simple algorithms and generates simple looking images. Photorealistic image synthesis software runs slowly on large expensive computers. The time has come for these two branches of computer graphics to merge. The speed and expense of graphics hardware is no longer the barrier to the wide acceptance of photorealism. There is every reason to believe that high quality image synthesis will become a standard capability of every graphics machine, from superworkstation to personal computer. The significant barrier has been the lack of a common language, an agreed-upon set of terms and conditions, for 3-D modeling systems to talk to 3-D rendering systems for computing an accurate rendition of that scene. Pixar has introduced RenderMan to serve as that common language. RenderMan, specifically the extensibility it offers in shading calculations, is discussed.

  9. Study of Perovskite QD Down-Converted LEDs and Six-Color White LEDs for Future Displays with Excellent Color Performance.

    PubMed

    Yoon, Hee Chang; Kang, Heejoon; Lee, Soyoung; Oh, Ji Hye; Yang, Heesun; Do, Young Rag

    2016-07-20

    A narrow-emitting red, green, and blue (RGB) perovskite quantum dot (PeQD)-based tricolored display system can widen the color gamut over the National Television System Committee (NTSC) to 120%, but this value is misleading with regard to the color perception of cyan and yellow reproduced in the narrow RGB spectra. We propose that a PeQD-based six-color display system can reproduce true-to-life spectral distributions with high fidelity, widen the color gamut, and close the cyan and yellow gap in the RGB tricolored display by adding cyan (Cy), yellowish green (Yg), and orange colors (Or). In this study, we demonstrated pure-colored CsPbX3 (X = Cl, Br, I, or their halide mixtures; Cl/Br and Br/I) PeQD-based monochromatic down-converted light-emitting diodes (DC-LED) for the first time, and we incorporated PeQDs with UV-curable binders and long-wavelength-pass-dichroic filters (LPDFs). CsPbX3 PeQD-based pure Cy-, G-, Yg-, Or-, R-emitting monochromatic DC-LED provide luminous efficacy (LE) values of 81, 184, 79, 80, and 35 lm/W, respectively, at 20 mA. We also confirmed the suitability and the possibility of access to future color-by-blue backlights for field-sequential-color liquid crystal displays, using six-color multipackage white LEDs, as well as future six-colored light-emitting devices with high vision and color performance. The fabricated six-color multipackage white LEDs exhibited an appropriate LE (62 lm/W at total 120 mA), excellent color qualities (color rendering index (CRI) = 96, special CRI for red (R9) = 97) at a correlated color temperature (CCT) of 6500 K, and a wide color gamut covering the NTSC up to 145% in the 1931 Commission International de l'Eclairage (CIE) color coordinates space. PMID:27349270

  10. Development of the IES method for evaluating the color rendition of light sources

    DOE PAGESBeta

    David, Aurelien; Fini, Paul T.; Houser, Kevin W.; Ohno, Yoshi; Royer, Michael P.; USA, Richland Washington; Smet, Kevin A. G.; Wei, Minchen; Whitehead, Lorne

    2015-06-08

    We have developed a two-measure system for evaluating light sources’ color rendition that builds upon conceptual progress of numerous researchers over the last two decades. The system quantifies the color fidelity and color gamut (change in object chroma) of a light source in comparison to a reference illuminant. The calculations are based on a newly developed set of reflectance data from real samples uniformly distributed in color space (thereby fairly representing all colors) and in wavelength space (thereby precluding artificial optimization of the color rendition scores by spectral engineering). The color fidelity score Rf is an improved version of themore » CIE color rendering index. The color gamut score Rg is an improved version of the Gamut Area Index. In combination, they provide two complementary assessments to guide the optimization of future light sources. This method summarizes the findings of the Color Metric Task Group of the Illuminating Engineering Society of North America (IES). It is adopted in the upcoming IES TM-30-2015, and is proposed for consideration with the International Commission on Illumination (CIE).« less

  11. Development of the IES method for evaluating the color rendition of light sources

    SciTech Connect

    David, Aurelien; Fini, Paul T.; Houser, Kevin W.; Ohno, Yoshi; Royer, Michael P.; USA, Richland Washington; Smet, Kevin A. G.; Whitehead, Lorne

    2015-06-08

    We have developed a two-measure system for evaluating light sources’ color rendition that builds upon conceptual progress of numerous researchers over the last two decades. The system quantifies the color fidelity and color gamut (change in object chroma) of a light source in comparison to a reference illuminant. The calculations are based on a newly developed set of reflectance data from real samples uniformly distributed in color space (thereby fairly representing all colors) and in wavelength space (thereby precluding artificial optimization of the color rendition scores by spectral engineering). The color fidelity score Rf is an improved version of the CIE color rendering index. The color gamut score Rg is an improved version of the Gamut Area Index. In combination, they provide two complementary assessments to guide the optimization of future light sources. This method summarizes the findings of the Color Metric Task Group of the Illuminating Engineering Society of North America (IES). It is adopted in the upcoming IES TM-30-2015, and is proposed for consideration with the International Commission on Illumination (CIE).

  12. Text Rendering: Beginning Literary Response.

    ERIC Educational Resources Information Center

    Robertson, Sandra L.

    1990-01-01

    Argues that "text rendering"--responding to oral readings by saying back remembered words or phrases--forces students to prolong their initial responses to texts and opens initial response to the influence of other readers. Argues that silence following oral readings allows words to sink into students' minds, creating individual images and…

  13. Color image simulation for underwater optics.

    PubMed

    Boffety, Matthieu; Galland, Frédéric; Allais, Anne-Gaëlle

    2012-08-10

    Underwater optical image simulation is a valuable tool for oceanic science, especially for the characterization of image processing techniques such as color restoration. In this context, simulating images with a correct color rendering is crucial. This paper presents an extension of existing image simulation models to RGB imaging. The influence of the spectral discretization of the model parameters on the color rendering of the simulated images is studied. It is especially shown that, if only RGB data of the scene chosen for simulations are available, a spectral reconstruction step prior to the simulations improves the image color rendering. PMID:22885575

  14. Compressive rendering: a rendering application of compressed sensing.

    PubMed

    Sen, Pradeep; Darabi, Soheil

    2011-04-01

    Recently, there has been growing interest in compressed sensing (CS), the new theory that shows how a small set of linear measurements can be used to reconstruct a signal if it is sparse in a transform domain. Although CS has been applied to many problems in other fields, in computer graphics, it has only been used so far to accelerate the acquisition of light transport. In this paper, we propose a novel application of compressed sensing by using it to accelerate ray-traced rendering in a manner that exploits the sparsity of the final image in the wavelet basis. To do this, we raytrace only a subset of the pixel samples in the spatial domain and use a simple, greedy CS-based algorithm to estimate the wavelet transform of the image during rendering. Since the energy of the image is concentrated more compactly in the wavelet domain, less samples are required for a result of given quality than with conventional spatial-domain rendering. By taking the inverse wavelet transform of the result, we compute an accurate reconstruction of the desired final image. Our results show that our framework can achieve high-quality images with approximately 75 percent of the pixel samples using a nonadaptive sampling scheme. In addition, we also perform better than other algorithms that might be used to fill in the missing pixel data, such as interpolation or inpainting. Furthermore, since the algorithm works in image space, it is completely independent of scene complexity. PMID:21311092

  15. Equivalent Colorings with "Maple"

    ERIC Educational Resources Information Center

    Cecil, David R.; Wang, Rongdong

    2005-01-01

    Many counting problems can be modeled as "colorings" and solved by considering symmetries and Polya's cycle index polynomial. This paper presents a "Maple 7" program link http://users.tamuk.edu/kfdrc00/ that, given Polya's cycle index polynomial, determines all possible associated colorings and their partitioning into equivalence classes. These…

  16. Microbial pathogen quality criteria of rendered products.

    PubMed

    Pandey, Pramod K; Biswas, Sagor; Kass, Philip

    2016-06-01

    The North American rendering industry processes approximately 24 million metric tons (Mt) of raw materials and produces more than 8 million Mt of rendered products. More than 85 % of rendered products produced annually in the USA are used for producing animal feed. Pathogen contamination in rendered products is an important and topical issue. Although elevated temperatures (115-140 °C) for 40-90 min during the standard rendering processes are mathematically sufficient to completely destroy commonly found pathogens, the presence of pathogens in rendered products has nevertheless been reported. Increased concern over the risk of microbial contamination in rendered products may require additional safeguards for producing pathogen-free rendered products. This study provides an overview of rendered products, existing microbial pathogen quality criteria of rendered products (MPQCR), limitations, and the scope of improving the MPQCR. PMID:27121572

  17. GPU-based Volume Rendering for Medical Image Visualization.

    PubMed

    Heng, Yang; Gu, Lixu

    2005-01-01

    During the quick advancements of medical image visualization and augmented virtual reality application, the low performance of the volume rendering algorithm is still a "bottle neck". To facilitate the usage of well developed hardware resource, a novel graphics processing unit (GPU)-based volume ray-casting algorithm is proposed in this paper. Running on a normal PC, it performs an interactive rate while keeping the same image quality as the traditional volume rendering algorithm does. Recently, GPU-accelerated direct volume rendering has positioned itself as an efficient tool for the display and visual analysis of volume data. However, for large sized medical image data, it often shows low efficiency for too large memories requested. Furthermore, it always holds a drawback of writing color buffers multi-times per frame. The proposed algorithm improves the situation by implementing ray casting operation completely in GPU. It needs only one slice plane from CPU and one 3Dtexture to store data when GPU calculates the two terminals of the ray and carries out the color blending operation in its pixel programs. So both the rendering speed and the memories consumed are improved, and the algorithm can deal most medical image data on normal PCs in the interactive speed. PMID:17281405

  18. Color temperature tunable white light emitting diodes packaged with an omni-directional reflector.

    PubMed

    Su, Jung-Chieh; Lu, Chun-Lin

    2009-11-23

    This study proposed a correlated color temperature (CCT) tunable phosphor-converted white light emitting diode (LED) with an omni-directional reflector (ODR). Applying current to each individual InGaN based ultraviolet, purple and blue source LED chip of the white LED package, we can achieve the CCT tunability. The optimum color properties of the resulting white light are (0.3347, 0.3384), 5398 K, 81, 3137-8746 K for color coordinates, CCT, color rendering index (CRI) and CCT tuning range, respectively. Roughening the ODR substrate, we solve the non-uniformity color distribution caused by the reflectance of the ODR and positioning of source LED chips. PMID:19997380

  19. Tuning the correlated color temperature of white LED with a guest-host liquid crystal.

    PubMed

    Chen, Haiwei; Luo, Zhenyue; Zhu, Ruidong; Hong, Qi; Wu, Shin-Tson

    2015-05-18

    We demonstrate an electro-optic method to tune the correlated color temperature (CCT) of white light-emitting-diode (WLED) with a color conversion film, consisting of fluorescent dichroic dye doped in a liquid crystal host. By controlling the molecular reorientation of dichroic dyes, the power ratio of the transmitted blue and red lights of the white light can be accurately manipulated, resulting in different CCT. In a proof-of-concept experiment, we showed that the CCT of a yellow phosphor-converted WLED can be tuned from 3200 K to 4100 K. With further optimizations, the tuning range could be enlarged to 2500 K with fairly good color performance: luminous efficacy of radiation (LER) > 300 lm/W, color rendering index (CRI) > 75, and Duv < 0.005. Besides, the operation voltage is lower than 5 V and good angular color uniformity is achieved with remote-phosphor coating. This approach is promising for next generation smart lighting. PMID:26074559

  20. Color rendition engine.

    PubMed

    Zukauskas, Artūras; Vaicekauskas, Rimantas; Vitta, Pranciškus; Tuzikas, Arūnas; Petrulis, Andrius; Shur, Michael

    2012-02-27

    A source of white light with continuously tuned color rendition properties, such as color fidelity, as well as color saturating and color dulling ability has been developed. The source, which is composed of red (R), amber (A), green (G), and blue (B) light-emitting diodes, has a spectral power distribution varied as a weighted sum of "white" RGB and AGB blends. At the RGB and AGB end-points, the source has a highest color saturating and color dulling ability, respectively, as follows from the statistical analysis of the color-shift vectors for 1269 Munsell samples. The variation of the weight parameter allows for continuously traversing all possible metameric RAGB blends, including that with the highest color fidelity. The source was used in a psychophysical experiment on the estimation of the color appearance of familiar objects, such as vegetables, fruits, and soft-drink cans of common brands, at correlated color temperatures of 3000 K, 4500 K, and 6500 K. By continuously tuning the weight parameter, each of 100 subjects selected RAGB blends that, to their opinion, matched lighting characterized as "most saturating," "most dulling," "most natural," and "preferential". The end-point RGB and AGB blends have been almost unambiguously attributed to "most saturating" and "most dulling" lighting, respectively. RAGB blends that render a highest number of colors with high fidelity have, on average, been attributed to "most natural" lighting. The "preferential" color quality of lighting has, on average, been matched to RAGB blends that provide color rendition with fidelity somewhat reduced in favor of a higher saturation. Our results infer that tunable "color rendition engines" can validate color rendition metrics and provide lighting meeting specific needs and preferences to color quality. PMID:22418343

  1. Image space adaptive volume rendering

    NASA Astrophysics Data System (ADS)

    Corcoran, Andrew; Dingliana, John

    2012-01-01

    We present a technique for interactive direct volume rendering which provides adaptive sampling at a reduced memory requirement compared to traditional methods. Our technique exploits frame to frame coherence to quickly generate a two-dimensional importance map of the volume which guides sampling rate optimisation and allows us to provide interactive frame rates for user navigation and transfer function changes. In addition our ray casting shader detects any inconsistencies in our two-dimensional map and corrects them on the fly to ensure correct classification of important areas of the volume.

  2. Impact of cross-regional differences on color rendition evaluation of white light sources.

    PubMed

    Smet, Kevin A G; Hanselaer, Peter

    2015-11-16

    In a study, involving laboratories from seven geographic regions, the memory colors of eleven familiar objects were investigated. Based on that study, one global and seven regional memory color rendition indices (MCRIs) are created and the impact of cross-regional differences on the evaluation of color rendition was investigated. A first analysis focuses on the impact on MCRI index values by comparing the regional index values, calculated for 401 light sources, with those of the global index. A second analysis examines the impact on predictive performance in terms of the visual appreciation and naturalness of rendered objects colors as evaluated in respectively twenty-one and fifteen experiments published in literature. Both analyses show that, although there are small differences in absolute level of color rendition, the regional metrics are generally comparable in terms of predicting light source rank order and correlation with visual data. Therefore, ànd considering between-region variability to be smaller than or of the same size as the within-region variability, a globally valid memory color rendition metric can be proposed without introducing substantial errors. Finally, Smet's Rm index, obtained using real objects, is suggested as a good approximation to that globally valid metric. PMID:26698502

  3. Color naming: color scientists do it between Munsell sheets of color

    NASA Astrophysics Data System (ADS)

    Beretta, Giordano B.; Moroney, Nathan M.

    2010-01-01

    With the advent of high dynamic range imaging and wide gamut color spaces, gamut mapping algorithms have to nudge image colors much more drastically to constrain them within a rendering device's gamut. Classical colorimetry is concerned with color matching and the developed color difference metrics are for small distances. For larger distances, categorization becomes a more useful concept. In the gamut mapping case, lexical distance induced by color names is a more useful metric, which translates to the condition that a nudged color may not cross a name boundary. The new problem is to find these color name boundaries. We compare the experimental procedures used for color naming by linguists, ethnologists, and color scientists and propose a methodology that leads to robust repeatable experiments.

  4. Linked-View Parallel Coordinate Plot Renderer

    Energy Science and Technology Software Center (ESTSC)

    2011-06-28

    This software allows multiple linked views for interactive querying via map-based data selection, bar chart analytic overlays, and high dynamic range (HDR) line renderings. The major component of the visualization package is a parallel coordinate renderer with binning, curved layouts, shader-based rendering, and other techniques to allow interactive visualization of multidimensional data.

  5. Volume Rendering of Heliospheric Data

    NASA Astrophysics Data System (ADS)

    Hick, P. P.; Jackson, B. V.; Bailey, M. J.; Buffington, A.

    2001-12-01

    We demonstrate some of the techniques we currently use for the visualization of heliospheric volume data. Our 3D volume data usually are derived from tomographic reconstructions of the solar wind density and velocity from remote sensing observations (e.g., Thomson scattering and interplanetary scintillation observations). We show examples of hardware-based volume rendering using the Volume Pro PCI board (from TeraRecon, Inc.). This board updates the display at a rate of up to 30 frames per second using a parallel projection algorithm, allowing the manipulation of volume data in real-time. In addition, the manipulation of 4D volume data (the 4th dimension usually representing time) enables the visualization in real-time of an evolving (time-dependent) data set. We also show examples of perspective projections using IDL. This work was supported through NASA grant NAG5-9423.

  6. Volume Rendering of AMR Simulations

    NASA Astrophysics Data System (ADS)

    Labadens, M.; Pomarède, D.; Chapon, D.; Teyssier, R.; Bournaud, F.; Renaud, F.; Grandjouan, N.

    2013-04-01

    High-resolution simulations often rely on the Adaptive Mesh Resolution (AMR) technique to optimize memory consumption versus attainable precision. While this technique allows for dramatic improvements in terms of computing performance, the analysis and visualization of its data outputs remain challenging. The lack of effective volume renderers for the octree-based AMR used by the RAMSES simulation program has led to the development of the solutions presented in this paper. Two custom algorithms are discussed, based on the splatting and the ray-casting techniques. Their usage is illustrated in the context of the visualization of a high-resolution, 6000-processor simulation of a Milky Way-like galaxy. Performance obtained in terms of memory management and parallelism speedup are presented.

  7. Matching rendered and real world images by digital image processing

    NASA Astrophysics Data System (ADS)

    Mitjà, Carles; Bover, Toni; Bigas, Miquel; Escofet, Jaume

    2010-05-01

    Recent advances in computer-generated images (CGI) have been used in commercial and industrial photography providing a broad scope in product advertising. Mixing real world images with those rendered from virtual space software shows a more or less visible mismatching between corresponding image quality performance. Rendered images are produced by software which quality performance is only limited by the resolution output. Real world images are taken with cameras with some amount of image degradation factors as lens residual aberrations, diffraction, sensor low pass anti aliasing filters, color pattern demosaicing, etc. The effect of all those image quality degradation factors can be characterized by the system Point Spread Function (PSF). Because the image is the convolution of the object by the system PSF, its characterization shows the amount of image degradation added to any taken picture. This work explores the use of image processing to degrade the rendered images following the parameters indicated by the real system PSF, attempting to match both virtual and real world image qualities. The system MTF is determined by the slanted edge method both in laboratory conditions and in the real picture environment in order to compare the influence of the working conditions on the device performance; an approximation to the system PSF is derived from the two measurements. The rendered images are filtered through a Gaussian filter obtained from the taking system PSF. Results with and without filtering are shown and compared measuring the contrast achieved in different final image regions.

  8. Rendering-oriented multiview video coding based on chrominance information reconstruction

    NASA Astrophysics Data System (ADS)

    Shao, Feng; Yu, Mei; Jiang, Gangyi; Zhang, Zhaoyang

    2010-05-01

    Three-dimensional (3-D) video systems are expected to be a next-generation visual application. Since multiview video for 3-D video systems is composed of color and associated depth information, its huge requirement for data storage and transmission is an important problem. We propose a rendering-oriented multiview video coding (MVC) method based on chrominance information reconstruction that incorporates the rendering technique into the MVC process. The proposed method discards certain chrominance information to reduce bitrates, and performs reasonable bitrate allocation between color and depth videos. At the decoder, a chrominance reconstruction algorithm is presented to achieve accurate reconstruction by warping the neighboring views and colorizing the luminance-only pixels. Experimental results show that the proposed method can save nearly 20% on bitrates against the results without discarding the chrominance information. Moreover, under a fixed bitrate budget, the proposed method can greatly improve the rendering quality.

  9. A novel method for designing dichroic color filter transmittance curves for lighting applications

    NASA Astrophysics Data System (ADS)

    Qi, Rui; Shum, Frank

    2014-09-01

    This paper focuses on designing dichroic filters for changing the color of light-emitting diode (LED) lamps. Dichroic filters are composed of multiple dielectric layers on a substrate. By applying a dichroic filter, some of the LED's spectral energy is reflected and some is transmitted, which changes the lamp's color. Conventional methods to obtain spectral transmittance curves have shortcomings. The design criteria for the transmittance curves are incompatible with the metrics used in lighting applications, such as correlated color temperature (CCT) and color rendering index (CRI). Thus, the color rendering performance and the optical transmission of a lighting system are not optimized. This observation leads to the development of a proposed method for designing dichroic filter transmittance curves to provide accurate color shift, high CRI, and sufficient optical transmission. The method initially uses the transmittance curve of an existing color filter that provides a roughly close color shift for the LED lamp to calculate the transmittance curve that causes an accurate color shift by polynomial approximation. Based on the approximated curve, a preliminary transmittance curve without the effect of the LED lamp's secondary optics is derived and verified in thin-film design and optical design software tools. Further, the derived preliminary transmittance curve is optimized by applying an algorithm to loop through a large amount of representative curves fluctuating near the preliminary curve. The resulting dichroic filter provides an accurate color shift (ΔCCT = -800±50K, Duv = ±0.003), high CRI (Ra and R9 <= 95), and sufficient luminous flux transmission (<= 70%).

  10. Progress in color night vision

    NASA Astrophysics Data System (ADS)

    Toet, Alexander; Hogervorst, Maarten A.

    2012-01-01

    We present an overview of our recent progress and the current state-of-the-art techniques of color image fusion for night vision applications. Inspired by previously developed color opponent fusing schemes, we initially developed a simple pixel-based false color-mapping scheme that yielded fused false color images with large color contrast and preserved the identity of the input signals. This method has been successfully deployed in different areas of research. However, since this color mapping did not produce realistic colors, we continued to develop a statistical color-mapping procedure that would transfer the color distribution of a given example image to a multiband nighttime image. This procedure yields a realistic color rendering. However, it is computationally expensive and achieves no color constancy since the mapping depends on the relative amounts of the different materials in the scene. By applying the statistical mapping approach in a color look-up-table framework, we finally achieved both color constancy and computational simplicity. This sample-based color transfer method is specific for different types of materials in a scene and can be easily adapted for the intended operating theatre and the task at hand. The method can be implemented as a look-up-table transform and is highly suitable for real-time implementations.

  11. Volume rendering for interactive 3D segmentation

    NASA Astrophysics Data System (ADS)

    Toennies, Klaus D.; Derz, Claus

    1997-05-01

    Combined emission/absorption and reflection/transmission volume rendering is able to display poorly segmented structures from 3D medical image sequences. Visual cues such as shading and color let the user distinguish structures in the 3D display that are incompletely extracted by threshold segmentation. In order to be truly helpful, analyzed information needs to be quantified and transferred back into the data. We extend our previously presented scheme for such display be establishing a communication between visual analysis and the display process. The main tool is a selective 3D picking device. For being useful on a rather rough segmentation, the device itself and the display offer facilities for object selection. Selective intersection planes let the user discard information prior to choosing a tissue of interest. Subsequently, a picking is carried out on the 2D display by casting a ray into the volume. The picking device is made pre-selective using already existing segmentation information. Thus, objects can be picked that are visible behind semi-transparent surfaces of other structures. Information generated by a later connected- component analysis can then be integrated into the data. Data examination is continued on an improved display letting the user actively participate in the analysis process. Results of this display-and-interaction scheme proved to be very effective. The viewer's ability to extract relevant information form a complex scene is combined with the computer's ability to quantify this information. The approach introduces 3D computer graphics methods into user- guided image analysis creating an analysis-synthesis cycle for interactive 3D segmentation.

  12. RenderToolbox3: MATLAB tools that facilitate physically based stimulus rendering for vision research

    PubMed Central

    Heasly, Benjamin S.; Cottaris, Nicolas P.; Lichtman, Daniel P.; Xiao, Bei; Brainard, David H.

    2014-01-01

    RenderToolbox3 provides MATLAB utilities and prescribes a workflow that should be useful to researchers who want to employ graphics in the study of vision and perhaps in other endeavors as well. In particular, RenderToolbox3 facilitates rendering scene families in which various scene attributes and renderer behaviors are manipulated parametrically, enables spectral specification of object reflectance and illuminant spectra, enables the use of physically based material specifications, helps validate renderer output, and converts renderer output to physical units of radiance. This paper describes the design and functionality of the toolbox and discusses several examples that demonstrate its use. We have designed RenderToolbox3 to be portable across computer hardware and operating systems and to be free and open source (except for MATLAB itself). RenderToolbox3 is available at https://github.com/DavidBrainard/RenderToolbox3. PMID:24511145

  13. Direct Volume Rendering of Curvilinear Volumes

    NASA Technical Reports Server (NTRS)

    Vaziri, Arsi; Wilhelms, J.; Challinger, J.; Alper, N.; Ramamoorthy, S.; Kutler, Paul (Technical Monitor)

    1998-01-01

    Direct volume rendering can visualize sampled 3D scalar data as a continuous medium, or extract features. However, it is generally slow. Furthermore, most algorithms for direct volume rendering have assumed rectilinear gridded data. This paper discusses methods for using direct volume rendering when the original volume is curvilinear, i.e. is divided into six-sided cells which are not necessarily equilateral hexahedra. One approach is to ray-cast such volumes directly. An alternative approach is to interpolate the sample volumes to a rectilinear grid, and use this regular volume for rendering. Advantages and disadvantages of the two approaches in terms of speed and image quality are explored.

  14. Color Blindness

    MedlinePlus

    ... rose in full bloom. If you have a color vision defect, you may see these colors differently than most people. There are three main kinds of color vision defects. Red-green color vision defects are the ...

  15. Color Blindness

    MedlinePlus

    ... rose in full bloom. If you have a color vision defect, you may see these colors differently than most people. There are three main kinds of color vision defects. Red-green color vision defects are the most ...

  16. Color Blindness

    MedlinePlus

    ... three color cone cells to determine our color perception. Color blindness can occur when one or more ... Anyone who experiences a significant change in color perception should see an ophthalmologist (Eye M.D.). Next ...

  17. Hierarchical image-based rendering using texture mapping hardware

    SciTech Connect

    Max, N

    1999-01-15

    Multi-layered depth images containing color and normal information for subobjects in a hierarchical scene model are precomputed with standard z-buffer hardware for six orthogonal views. These are adaptively selected according to the proximity of the viewpoint, and combined using hardware texture mapping to create ''reprojected'' output images for new viewpoints. (If a subobject is too close to the viewpoint, the polygons in the original model are rendered.) Specific z-ranges are selected from the textures with the hardware alpha test to give accurate 3D reprojection. The OpenGL color matrix is used to transform the precomputed normals into their orientations in the final view, for hardware shading.

  18. Applying Color.

    ERIC Educational Resources Information Center

    Burton, David

    1984-01-01

    Most schools teach the triadic color system, utilizing red, blue, and yellow as primary colors. Other systems, such as additive and subtractive color systems, Munsell's Color Notation System, and the Hering Opponent Color Theory, can broaden children's concepts and free them to better choose color in their own work. (IS)

  19. Color temperature tunable white light LED system

    NASA Astrophysics Data System (ADS)

    Speier, Ingo; Salsbury, Marc

    2006-08-01

    Efficient white light LED systems with continuously tunable color temperature (CT) over a range of 3000 K to 6500 K are reviewed. Typically, white light sources have a fixed CT and color rendering index (CRI). White light with user-specified color temperatures is currently generated by solid-state systems with red green blue ("R/G/B"), red green blue amber ("R/G/B/A"), and warm white cool white ("WW/CW") LED combinations, but their performance is suboptimal for architectural lighting applications. We propose and discuss an LED module with a combination of warm white, green and blue ("WW/G/B") LEDs. In this scenario, the white LEDs have fixed intensity, while the blue and green LED intensities are adjusted to shift the LED module chromaticity along the blackbody locus. We also propose and discuss an LED module with a combination of red, green, blue, and cool white ("R/G/B/CW") LEDs. The white LEDs still have a fixed intensity, while the intensities of the red, green, and blue LEDs are again adjusted to shift the LED module chromaticity along the blackbody locus. The white LEDs ensure that an improved CRI is maintained in comparison to a simple "R/G/B" solution.

  20. OLED-based physiologically-friendly very low-color temperature illumination for night

    NASA Astrophysics Data System (ADS)

    Jou, Jwo-Huei; Shen, Shih-Ming; Tang, Ming-Chun; Chen, Pin-Chu; Chen, Szu-Hao; Wang, Yi-Shan; Chen, Chien-Chih; Wang, Ching-Chun; Hsieh, Chun-Yu; Lin, Chin-Chiao; Chen, Chien-Tien

    2012-09-01

    Numerous medical research studies reveal intense white or blue light to drastically suppress at night the secretion of melatonin (MLT), a protective oncostatic hormone. Lighting devices with lower color-temperature (CT) possess lesser MLT suppression effect based on the same luminance, explaining why physicians have long been calling for the development of lighting sources with low CT or free from blue emission for use at night to safeguard human health. We will demonstrate in the presentation the fabrication of OLED devices with very-low CT, especially those with CT much lower than that of incandescent bulbs (2500K) or even candles (2000K). Without any light extraction method, OLEDs with an around 1800K CT are easily obtainable with an efficacy of 30 lm/W at 1,000 nits. To also ensure high color-rendering to provide visual comfort, low CT OLEDs composing long wavelength dominant 5-spectrum emission have been fabricated. While keeping the color-rendering index as high as 85 and CT as low as 2100K, the resulting efficacy can also be much greater than that of incandescent bulbs (15 lm/W), proving these low CT OLED devices to be also capable of being energy-saving and high quality. The color-temperature can be further decreased to 1700K or lower upon removing the undesired short wavelength emission but on the cost of losing some color rendering index. It is hoped that the devised energy-saving, high quality low CT OLED could properly echo the call for a physiologically-friendly illumination for night, and more attention could be drawn to the development of MLT suppression-less non-white light.

  1. Parallel rendering techniques for massively parallel visualization

    SciTech Connect

    Hansen, C.; Krogh, M.; Painter, J.

    1995-07-01

    As the resolution of simulation models increases, scientific visualization algorithms which take advantage of the large memory. and parallelism of Massively Parallel Processors (MPPs) are becoming increasingly important. For large applications rendering on the MPP tends to be preferable to rendering on a graphics workstation due to the MPP`s abundant resources: memory, disk, and numerous processors. The challenge becomes developing algorithms that can exploit these resources while minimizing overhead, typically communication costs. This paper will describe recent efforts in parallel rendering for polygonal primitives as well as parallel volumetric techniques. This paper presents rendering algorithms, developed for massively parallel processors (MPPs), for polygonal, spheres, and volumetric data. The polygon algorithm uses a data parallel approach whereas the sphere and volume render use a MIMD approach. Implementations for these algorithms are presented for the Thinking Ma.chines Corporation CM-5 MPP.

  2. Capturing, processing, and rendering real-world scenes

    NASA Astrophysics Data System (ADS)

    Nyland, Lars S.; Lastra, Anselmo A.; McAllister, David K.; Popescu, Voicu; McCue, Chris; Fuchs, Henry

    2000-12-01

    While photographs vividly capture a scene from a single viewpoint, it is our goal to capture a scene in such a way that a viewer can freely move to any viewpoint, just as he or she would in an actual scene. We have built a prototype system to quickly digitize a scene using a laser rangefinder and a high-resolution digital camera that accurately captures a panorama of high-resolution range and color information. With real-world scenes, we have provided data to fuel research in many area, including representation, registration, data fusion, polygonization, rendering, simplification, and reillumination. The real-world scene data can be used for many purposes, including immersive environments, immersive training, re-engineering and engineering verification, renovation, crime-scene and accident capture and reconstruction, archaeology and historic preservation, sports and entertainment, surveillance, remote tourism and remote sales. We will describe our acquisition system, the necessary processing to merge data from the multiple input devices and positions. We will also describe high quality rendering using the data we have collected. Issues about specific rendering accelerators and algorithms will also be presented. We will conclude by describing future uses and methods of collection for real- world scene data.

  3. 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.

  4. Color uniformity and data simulation in high-power RGB LED modules using different LED-chips arrays

    NASA Astrophysics Data System (ADS)

    Tu, Yan; Jin, Shangzhong; Wang, Yanhua; Dou, Liangliang

    2007-11-01

    The continuing research efforts in white light created by mixing red, green and blue light emitting diodes (RGB LED) will allow their applications in high quality lighting systems in the (near) future. There are still many issues to tackle in this kind of light source, for instance the color uniformity and the change of color-render property owing to the change of LED's temperature. In this paper we simulate the effects on color uniformity of the near-field light distribution due to different LED-chips arrays (at optimum packaging density for uniform irradiance) using High-Power RGB LED-chips. The results showing the color uniformity of near-field which can be achieved with different RGB LED-chips arrays are presented. Several configurations of RGB LED-chips arrays and relevant data for color variation are given respectively. An analysis of luminous efficacy of radiation (LER) and color rendering index (CRI) of this source is performed, which are affected by the peak wavelength, spectral width, and the output peak emission power ratio of LED-chips.

  5. Object-oriented parallel polygon rendering

    SciTech Connect

    Heiland, R.W.

    1994-09-01

    Since many scientific datasets can be visualized using some polygonal representation, a polygon renderer has broad use for scientific visualization. With today`s high performance computing applications producing very large datasets, a parallel polygon renderer is a necessary tool for keeping the compute-visualize cycle at a minimum. This paper presents a DOIV on renderer that combines the shared-memory and message-passing models of parallel programming. It uses the Global Arrays library, a shared-memory programming toolkit for distributed memory machines. The experience of using an object oriented approach for software design and development is also discussed.

  6. High-quality anatomical structure enhancement for cardiac image dynamic volume rendering

    NASA Astrophysics Data System (ADS)

    Zhang, Qi; Eagleson, Roy; Guiraudon, Gerard M.; Peters, Terry M.

    2008-03-01

    Dynamic volume rendering of the beating heart is an important element in cardiac disease diagnosis and therapy planning, providing the clinician with insight into the internal cardiac structure and functional behavior. Most clinical applications tend to focus upon a particular set of organ structures, and in the case of cardiac imaging, it would be helpful to embed anatomical features into the dynamic volume that are of particular importance to an intervention. A uniform transfer function (TF), such as is generally employed in volume rendering, cannot effectively isolate such structures because of the lack of spatial information and the small intensity differences between adjacent tissues. Explicit segmentation is a powerful way to approach this problem, which usually yields a single binary mask volume (MV), where a unit value in a voxel within the MV acts as a tag label representing the anatomical structure of interest (ASOI). These labels are used to determine the TF employed to adjust the ASOI display. Traditional approaches for rendering such segmented volumetric datasets usually deliver unsatisfactory results, such as noninteractive rendering speed, low image quality, intermixing artifacts along the rendered subvolume boundaries, and speckle noise. In this paper, we introduce a new "color coding" approach, based on the graphics processing unit (GPU) accelerated raycasting algorithm and a pre-integrated voxel classification method, to address this problem. The mask tag labels derived from segmentation are first smoothed with a Gaussian filter, and multiple TFs are designed for each of the MVs and the source cardiac volume respectively, mapping the voxel's intensity to color and opacity at each sampling point along the casting ray. The resultant values are composited together using a boundary color adjustment technique, which acts as "coding" the segmented anatomical structure information into the rendered source volume of the beating heart. Our algorithm

  7. Fast volume rendering for medical image.

    PubMed

    Ying, Hu; Xin-He, Xu

    2005-01-01

    In orders to improve the rendering speed of ray casting and make this technique a practical routine in medical applications, two new and improved techniques are described in this paper. First, an integrated method using "proximity clouds" technique is applied to speed up ray casting. The second technique for speeding up the 3D rendering is done through a parallel implementation based on "single computer multi CPU" model Four groups of CT data sets have been used to validate the improvement of the rendering speed. The result shown that the interactive rendering speed is up to 6-10 fps, which is almost real-time making our algorithm practical in medical visualization routine. PMID:17281409

  8. Color blindness

    MedlinePlus

    ... have trouble telling the difference between red and green. This is the most common type of color ... color blindness often have problems seeing reds and greens, too. The most severe form of color blindness ...

  9. Color blindness

    MedlinePlus

    ... care provider or eye specialist can check your color vision in several ways. Testing for color blindness is ... Adams AJ, Verdon WA, Spivey BE. Color vision. In: Tasman W, Jaeger EA, eds. ... PA: Lippincott Williams & Wilkins; 2013:vol. 2, chap ...

  10. Foundations for Measuring Volume Rendering Quality

    NASA Technical Reports Server (NTRS)

    Williams, Peter L.; Uselton, Samuel P.; Chancellor, Marisa K. (Technical Monitor)

    1997-01-01

    The goal of this paper is to provide a foundation for objectively comparing volume rendered images. The key elements of the foundation are: (1) a rigorous specification of all the parameters that need to be specified to define the conditions under which a volume rendered image is generated; (2) a methodology for difference classification, including a suite of functions or metrics to quantify and classify the difference between two volume rendered images that will support an analysis of the relative importance of particular differences. The results of this method can be used to study the changes caused by modifying particular parameter values, to compare and quantify changes between images of similar data sets rendered in the same way, and even to detect errors in the design, implementation or modification of a volume rendering system. If one has a benchmark image, for example one created by a high accuracy volume rendering system, the method can be used to evaluate the accuracy of a given image.

  11. NASA 1981 photography index

    NASA Technical Reports Server (NTRS)

    1982-01-01

    An index of representative photographs is presented. Color transparencies and black and white glossies of major launches, Mariner spacecraft, Pioneer spacecraft, planets and other space phenomena, Skylab, space shuttle, Viking spacecraft, and Voyager spacecraft are included.

  12. Polymeric Inverse Glasses for Development of Noniridescent Structural Colors in Full Visible Range.

    PubMed

    Lee, Gun Ho; Sim, Jae Young; Kim, Shin-Hyun

    2016-05-18

    Amorphous colloidal array with short-range order displays noniridescent structural colors due to the isotropic nature of the colloidal arrangement. The low angle dependence renders the colloidal glasses, which is promising for various coloration applications. Nevertheless, the colloidal glasses are difficult to develop red structural color due to strong cavity-like resonance from individual particles in the blue region. To suppress the cavity mode and develop the colors in the full visible range, we prepare inverse glasses composed of amorphous array of air cavities with short-range order. To produce the structures in a simple and reproducible manner, monodisperse silica particles are dispersed in a photocurable resin of poly(ethylene glycol) dimethacrylate (PEGDMA) at a volume fraction of 0.3. The particles spontaneously form the amorphous array with short-range order, which is rapidly captured in polymeric films by photopolymerization of the resin. Selective removal of silica particles from the polymerized resin leaves behind amorphous array of air cavities. The inverse glasses display structural colors with negligible backscattering in blue due to short optical path and low index in each cavity. Therefore, the colors can be tuned in full visible range by simply controlling the cavity size. The photocurable suspensions of silica particles can be patterned by photolithography, which enables the production of freestanding films containing patterned inverse glasses with noniridescent structural colors. PMID:27124719

  13. Image-based rendering method for mapping endoscopic video onto CT-based endoluminal views

    NASA Astrophysics Data System (ADS)

    Rai, Lav; Higgins, William E.

    2006-03-01

    One of the indicators of early lung cancer is a color change in airway mucosa. Bronchoscopy of the major airways can provide high-resolution color video of the airway tree's mucosal surfaces. In addition, 3D MDCT chest images provide 3D structural information of the airways. Unfortunately, the bronchoscopic video contains no explicit 3D structural and position information, and the 3D MDCT data captures no color or textural information of the mucosa. A fusion of the topographical information from the 3D CT data and the color information from the bronchoscopic video, however, enables realistic 3D visualization, navigation, localization, and quantitative color-topographic analysis of the airways. This paper presents a method for topographic airway-mucosal surface mapping from bronchoscopic video onto 3D MDCT endoluminal views. The method uses registered video images and CT-based virtual endoscopic renderings of the airways. The visibility and depth data are also generated by the renderings. Uniform sampling and over-scanning of the visible triangles are done before they are packed into a texture space. The texels are then re-projected onto video images and assigned color values based on depth and illumination data obtained from renderings. The texture map is loaded into the rendering engine to enable real-time navigation through the combined 3D CT surface and bronchoscopic video data. Tests were performed on pre-recorded bronchoscopy patient video and associated 3D MDCT scans. Results show that we can effectively accomplish mapping over a continuous sequence of airway images spanning several generations of airways.

  14. Color correction optimization with hue regularization

    NASA Astrophysics Data System (ADS)

    Zhang, Heng; Liu, Huaping; Quan, Shuxue

    2011-01-01

    Previous work has suggested that observers are capable of judging the quality of an image without any knowledge of the original scene. When no reference is available, observers can extract the apparent objects in an image and compare them with the typical colors of similar objects recalled from their memories. Some generally agreed upon research results indicate that although perfect colorimetric rendering is not conspicuous and color errors can be well tolerated, the appropriate rendition of certain memory colors such as skin, grass, and sky is an important factor in the overall perceived image quality. These colors are appreciated in a fairly consistent manner and are memorized with slightly different hues and higher color saturation. The aim of color correction for a digital color pipeline is to transform the image data from a device dependent color space to a target color space, usually through a color correction matrix which in its most basic form is optimized through linear regressions between the two sets of data in two color spaces in the sense of minimized Euclidean color error. Unfortunately, this method could result in objectionable distortions if the color error biased certain colors undesirably. In this paper, we propose a color correction optimization method with preferred color reproduction in mind through hue regularization and present some experimental results.

  15. Skin Cancer in Skin of Color

    PubMed Central

    Bradford, Porcia T.

    2009-01-01

    Skin cancers in skin of color often present atypically or with advanced stage in comparison to Caucasian patients. Health care providers must maintain a high index of suspicion when examining skin lesions in skin of color. PMID:19691228

  16. Standardized rendering from IR surveillance motion imagery

    NASA Astrophysics Data System (ADS)

    Prokoski, F. J.

    2014-06-01

    Government agencies, including defense and law enforcement, increasingly make use of video from surveillance systems and camera phones owned by non-government entities.Making advanced and standardized motion imaging technology available to private and commercial users at cost-effective prices would benefit all parties. In particular, incorporating thermal infrared into commercial surveillance systems offers substantial benefits beyond night vision capability. Face rendering is a process to facilitate exploitation of thermal infrared surveillance imagery from the general area of a crime scene, to assist investigations with and without cooperating eyewitnesses. Face rendering automatically generates greyscale representations similar to police artist sketches for faces in surveillance imagery collected from proximate locations and times to a crime under investigation. Near-realtime generation of face renderings can provide law enforcement with an investigation tool to assess witness memory and credibility, and integrate reports from multiple eyewitnesses, Renderings can be quickly disseminated through social media to warn of a person who may pose an immediate threat, and to solicit the public's help in identifying possible suspects and witnesses. Renderings are pose-standardized so as to not divulge the presence and location of eyewitnesses and surveillance cameras. Incorporation of thermal infrared imaging into commercial surveillance systems will significantly improve system performance, and reduce manual review times, at an incremental cost that will continue to decrease. Benefits to criminal justice would include improved reliability of eyewitness testimony and improved accuracy of distinguishing among minority groups in eyewitness and surveillance identifications.

  17. Colorful Chemistry.

    ERIC Educational Resources Information Center

    Williams, Suzanne

    1991-01-01

    Described is an color-making activity where students use food coloring, eyedroppers, and water to make various colored solutions. Included are the needed materials and procedures. Students are asked to write up the formulas for making their favorite color. (KR)

  18. Feature-driven data exploration for volumetric rendering.

    PubMed

    Woo, Insoo; Maciejewski, Ross; Gaither, Kelly P; Ebert, David S

    2012-10-01

    We have developed an intuitive method to semiautomatically explore volumetric data in a focus-region-guided or value-driven way using a user-defined ray through the 3D volume and contour lines in the region of interest. After selecting a point of interest from a 2D perspective, which defines a ray through the 3D volume, our method provides analytical tools to assist in narrowing the region of interest to a desired set of features. Feature layers are identified in a 1D scalar value profile with the ray and are used to define default rendering parameters, such as color and opacity mappings, and locate the center of the region of interest. Contour lines are generated based on the feature layer level sets within interactively selected slices of the focus region. Finally, we utilize feature-preserving filters and demonstrate the applicability of our scheme to noisy data. PMID:22291153

  19. Depth remapping using seam carving for depth image based rendering

    NASA Astrophysics Data System (ADS)

    Tsubaki, Ikuko; Iwauchi, Kenichi

    2015-03-01

    Depth remapping is a technique to control depth range of stereo images. Conventional remapping which uses a transform function in the whole image has a stable characteristic, however it sometimes reduces the 3D appearance too much. To cope with this problem, a depth remapping method which preserves the details of depth structure is proposed. We apply seam carving, which is an effective technique for image retargeting, to depth remapping. An extended depth map is defined as a space-depth volume, and a seam surface which is a 2D monotonic and connected manifold is introduced. The depth range is reduced by removing depth values on the seam surface from the space-depth volume. Finally a stereo image pair is synthesized from the corrected depth map and an input color image by depth image based rendering.

  20. A Parallel Rendering Algorithm for MIMD Architectures

    NASA Technical Reports Server (NTRS)

    Crockett, Thomas W.; Orloff, Tobias

    1991-01-01

    Applications such as animation and scientific visualization demand high performance rendering of complex three dimensional scenes. To deliver the necessary rendering rates, highly parallel hardware architectures are required. The challenge is then to design algorithms and software which effectively use the hardware parallelism. A rendering algorithm targeted to distributed memory MIMD architectures is described. For maximum performance, the algorithm exploits both object-level and pixel-level parallelism. The behavior of the algorithm is examined both analytically and experimentally. Its performance for large numbers of processors is found to be limited primarily by communication overheads. An experimental implementation for the Intel iPSC/860 shows increasing performance from 1 to 128 processors across a wide range of scene complexities. It is shown that minimal modifications to the algorithm will adapt it for use on shared memory architectures as well.

  1. Smooth transitions between bump rendering algorithms

    SciTech Connect

    Becker, B.G. Max, N.L. |

    1993-01-04

    A method is described for switching smoothly between rendering algorithms as required by the amount of visible surface detail. The result will be more realism with less computation for displaying objects whose surface detail can be described by one or more bump maps. The three rendering algorithms considered are bidirectional reflection distribution function (BRDF), bump-mapping, and displacement-mapping. The bump-mapping has been modified to make it consistent with the other two. For a given viewpoint, one of these algorithms will show a better trade-off between quality, computation time, and aliasing than the other two. Thus, it needs to be determined for any given viewpoint which regions of the object(s) will be rendered with each algorithm The decision as to which algorithm is appropriate is a function of distance, viewing angle, and the frequency of bumps in the bump map.

  2. Collaborative Graphic Rendering for Improving Visual Experience

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoxin; Pei, Guodong

    Handheld devices such as UMPC, though convenient, bear weakness of size constraint for display. To mitigate such a problem and enhance user experience for owners of small devices, in this paper we design a collaborative rendering platform. When running game graphic applications at a handheld, the generated OpenGL graphic commands are intercepted and then delivered to a device with a larger display. The graphics are rendered and displayed at that device. The performance of the collaborative rendering platform is determined by graphic computing resources and network bandwidth. Analysis and simulation prove that other than providing a better display, the collaborative system can improve game experience also by increasing frame rates. In particular, at a low computing cost, a further collaboration between GPUs of collaborators can improve frame rate by eliminating the negative impact from network delay on applications that require GPU feedback.

  3. Mobile Volume Rendering: Past, Present and Future.

    PubMed

    Noguera, José M; Jiménez, J Roberto

    2016-02-01

    Volume rendering has been a relevant topic in scientific visualization for the last decades. However, the exploration of reasonably big volume datasets requires considerable computing power, which has limited this field to the desktop scenario. But the recent advances in mobile graphics hardware have motivated the research community to overcome these restrictions and to bring volume graphics to these ubiquitous handheld platforms. This survey presents the past and present work on mobile volume rendering, and is meant to serve as an overview and introduction to the field. It proposes a classification of the current efforts and covers aspects such as advantages and issues of the mobile platforms, rendering strategies, performance and user interfaces. The paper ends by highlighting promising research directions to motivate the development of new and interesting mobile volume solutions. PMID:26731459

  4. Interactive stereoscopic rendering of volumetric environments.

    PubMed

    Wan, Ming; Zhang, Nan; Qu, Huamin; Kaufman, Arie E

    2004-01-01

    We present an efficient stereoscopic rendering algorithm supporting interactive navigation through large-scale 3D voxel-based environments. In this algorithm, most of the pixel values of the right image are derived from the left image by a fast 3D warping based on a specific stereoscopic projection geometry. An accelerated volumetric ray casting then fills the remaining gaps in the warped right image. Our algorithm has been parallelized on a multiprocessor by employing effective task partitioning schemes and achieved a high cache coherency and load balancing. We also extend our stereoscopic rendering to include view-dependent shading and transparency effects. We have applied our algorithm in two virtual navigation systems, flythrough over terrain and virtual colonoscopy, and reached interactive stereoscopic rendering rates of more than 10 frames per second on a 16-processor SGI Challenge. PMID:15382695

  5. Color tunable LED spot lighting

    NASA Astrophysics Data System (ADS)

    Hoelen, C.; Ansems, J.; Deurenberg, P.; van Duijneveldt, W.; Peeters, M.; Steenbruggen, G.; Treurniet, T.; Valster, A.; ter Weeme, J. W.

    2006-08-01

    A new trend in illumination is to use dynamic light to set or dynamically vary the ambience of a room or office. For this we need color tunable spots that can reliably vary over at least a wide range of color temperatures, and preferably also more saturated colors. LEDs are in principle ideally suited for this application thanks to their nature of emitting light in a relatively narrow band. For color tunable spot lighting based on the concept of mixing RGB LED colors, the key results have been presented before. Limitations of these 3-intrinsic-color mixing systems with high color rendering properties are found in a limited operating temperature range due to wavelength shifts, a limited color temperature range, and a low maximum operating temperature due to a strong flux decrease with increasing temperature. To overcome these limitations, a 3-color R pcGB system with phosphor-converted red (R pc) and a 4-color RAGB system have been investigated. With both systems, a CRI of at least 80 can be maintained over the relevant color temperature range of approximately 2700 K to 6500 K. In this paper we compare these concepts on overall system aspects and report on the performance of prototype spot lamps. The main features of the RAGB and R pcGB spot lamp concepts can be summarized as: 1) The RAGB spot overcomes CRI and gamut shortcomings of RGB light sources and gives much freedom in wavelength selection, but suffers from temperature sensitivity and complex controls; 2) The R pcGB spot overcomes shortcomings concerning CRI and thermal dependence of RGB sources and enables relatively simple controls, but needs an improved overall red efficacy. With both color concepts, prototype spot lamps have been built. The amber to red emitting nitridosilicate-based phosphors can be wavelength-tuned for optimal performance, which is found at a peak emission around 610 nm for high color quality systems. This results in a simple and very robust system with good color consistency. For the

  6. Fast polyhedral cell sorting for interactive rendering of unstructured grids

    SciTech Connect

    Combra, J; Klosowski, J T; Max, N; Silva, C T; Williams, P L

    1998-10-30

    Direct volume rendering based on projective methods works by projecting, in visibility order, the polyhedral cells of a mesh onto the image plane, and incrementally compositing the cell's color and opacity into the final image. Crucial to this method is the computation of a visibility ordering of the cells. If the mesh is ''well-behaved'' (acyclic and convex), then the MPVO method of Williams provides a very fast sorting algorithm; however, this method only computes an approximate ordering in general datasets, resulting in visual artifacts when rendered. A recent method of Silva et al. removed the assumption that the mesh is convex, by means of a sweep algorithm used in conjunction with the MPVO method; their algorithm is substantially faster than previous exact methods for general meshes. In this paper we propose a new technique, which we call BSP-XMPVO, which is based on a fast and simple way of using binary space partitions on the boundary elements of the mesh to augment the ordering produced by MPVO. Our results are shown to be orders of magnitude better than previous exact methods of sorting cells.

  7. Direct Volume Rendering with Shading via Three-Dimensional Textures

    NASA Technical Reports Server (NTRS)

    Van Gelder, Allen; Kim, Kwansik

    1996-01-01

    A new and easy-to-implement method for direct volume rendering that uses 3D texture maps for acceleration, and incorporates directional lighting, is described. The implementation, called Voltx, produces high-quality images at nearly interactive speeds on workstations with hardware support for three-dimensional texture maps. Previously reported methods did not incorporate a light model, and did not address issues of multiple texture maps for large volumes. Our research shows that these extensions impact performance by about a factor of ten. Voltx supports orthographic, perspective, and stereo views. This paper describes the theory and implementation of this technique, and compares it to the shear-warp factorization approach. A rectilinear data set is converted into a three-dimensional texture map containing color and opacity information. Quantized normal vectors and a lookup table provide efficiency. A new tesselation of the sphere is described, which serves as the basis for normal-vector quantization. A new gradient-based shading criterion is described, in which the gradient magnitude is interpreted in the context of the field-data value and the material classification parameters, and not in isolation. In the rendering phase, the texture map is applied to a stack of parallel planes, which effectively cut the texture into many slabs. The slabs are composited to form an image.

  8. Volume Rendering for Curvilinear and Unstructured Grids

    SciTech Connect

    Max, N; Williams, P; Silva, C; Cook, R

    2003-03-05

    We discuss two volume rendering methods developed at Lawrence Livermore National Laboratory. The first, cell projection, renders the polygons in the projection of each cell. It requires a global visibility sort in order to composite the cells in back to front order, and we discuss several different algorithms for this sort. The second method uses regularly spaced slice planes perpendicular to the X, Y, or Z axes, which slice the cells into polygons. Both methods are supplemented with anti-aliasing techniques to deal with small cells that might fall between pixel samples or slice planes, and both have been parallelized.

  9. Efficient hardware accelerated rendering of multiple volumes by data dependent local render functions

    NASA Astrophysics Data System (ADS)

    Lehmann, Helko; Geller, Dieter; Weese, Jürgen; Kiefer, Gundolf

    2007-03-01

    The inspection of a patient's data for diagnostics, therapy planning or therapy guidance involves an increasing number of 3D data sets, e.g. acquired by different imaging modalities, with different scanner settings or at different times. To enable viewing of the data in one consistent anatomical context fused interactive renderings of multiple 3D data sets are desirable. However, interactive fused rendering of typical medical data sets using standard computing hardware remains a challenge. In this paper we present a method to render multiple 3D data sets. By introducing local rendering functions, i.e. functions that are adapted to the complexity of the visible data contained in the different regions of a scene, we can ensure that the overall performance for fused rendering of multiple data sets depends on the actual amount of visible data. This is in contrast to other approaches where the performance depends mainly on the number of rendered data sets. We integrate the method into a streaming rendering architecture with brick-based data representations of the volume data. This enables efficient handling of data sets that do not fit into the graphics board memory and a good utilization of the texture caches. Furthermore, transfer and rendering of volume data that does not contribute to the final image can be avoided. We illustrate the benefits of our method by experiments with clinical data.

  10. How colorful! A feature it is, isn't it?

    NASA Astrophysics Data System (ADS)

    Lebowsky, Fritz

    2015-01-01

    A display's color subpixel geometry provides an intriguing opportunity for improving readability of text. True type fonts can be positioned at the precision of subpixel resolution. With such a constraint in mind, how does one need to design font characteristics? On the other hand, display manufactures try hard in addressing the color display's dilemma: smaller pixel pitch and larger display diagonals strongly increase the total number of pixels. Consequently, cost of column and row drivers as well as power consumption increase. Perceptual color subpixel rendering using color component subsampling may save about 1/3 of color subpixels (and reduce power dissipation). This talk will try to elaborate the following questions, based on simulation of several different layouts of subpixel matrices: Up to what level are display device constraints compatible with software specific ideas of rendering text? How much of color contrast will remain? How to best consider preferred viewing distance for readability of text? How much does visual acuity vary at 20/20 vision? Can simplified models of human visual color perception be easily applied to text rendering on displays? How linear is human visual contrast perception around band limit of a display's spatial resolution? How colorful does the rendered text appear on the screen? How much does viewing angle influence the performance of subpixel layouts and color subpixel rendering?

  11. Solid-state lamps with optimized color saturation ability.

    PubMed

    Zukauskas, Artūras; Vaicekauskas, Rimantas; Shur, Michael

    2010-02-01

    Spectral power distribution of trichromatic clusters of light-emitting diodes (LEDs) was optimized for rendering the highest number of colors with a perceptually noticeable gain in chroma (color saturation) out of 1269 Munsell samples. The basic tradeoffs of the number of colors rendered with increased saturation with the number of colors rendered with high fidelity and with luminous efficacy of radiation were established. High-saturation RGB clusters composed of commercially available AlGaInP and InGaN LEDs were modeled for a standard set of correlated color temperatures and the stability of the color saturation ability of the clusters against the drift of peak wavelengths was investigated. PMID:20174057

  12. Text What?! What Is Text Rendering?

    ERIC Educational Resources Information Center

    Davis-Haley, Rachel

    2004-01-01

    Text rendering is a method of deconstructing text that allows students to make decisions regarding the importance of the text, select the portions that are most meaningful to them, and then share it with classmates--all without fear of being ridiculed. The research on students constructing meaning from text is clear. In order for knowledge to…

  13. 3-D Volume Rendering of Sand Specimen

    NASA Technical Reports Server (NTRS)

    2004-01-01

    Computed tomography (CT) images of resin-impregnated Mechanics of Granular Materials (MGM) specimens are assembled to provide 3-D volume renderings of density patterns formed by dislocation under the external loading stress profile applied during the experiments. Experiments flown on STS-79 and STS-89. Principal Investigator: Dr. Stein Sture

  14. Rendering Visible: Painting and Sexuate Subjectivity

    ERIC Educational Resources Information Center

    Daley, Linda

    2015-01-01

    In this essay, I examine Luce Irigaray's aesthetic of sexual difference, which she develops by extrapolating from Paul Klee's idea that the role of painting is to render the non-visible rather than represent the visible. This idea is the premise of her analyses of phenomenology and psychoanalysis and their respective contributions to understanding…

  15. Rapid Decimation for Direct Volume Rendering

    NASA Technical Reports Server (NTRS)

    Gibbs, Jonathan; VanGelder, Allen; Verma, Vivek; Wilhelms, Jane

    1997-01-01

    An approach for eliminating unnecessary portions of a volume when producing a direct volume rendering is described. This reduction in volume size sacrifices some image quality in the interest of rendering speed. Since volume visualization is often used as an exploratory visualization technique, it is important to reduce rendering times, so the user can effectively explore the volume. The methods presented can speed up rendering by factors of 2 to 3 with minor image degradation. A family of decimation algorithms to reduce the number of primitives in the volume without altering the volume's grid in any way is introduced. This allows the decimation to be computed rapidly, making it easier to change decimation levels on the fly. Further, because very little extra space is required, this method is suitable for the very large volumes that are becoming common. The method is also grid-independent, so it is suitable for multiple overlapping curvilinear and unstructured, as well as regular, grids. The decimation process can proceed automatically, or can be guided by the user so that important regions of the volume are decimated less than unimportant regions. A formal error measure is described based on a three-dimensional analog of the Radon transform. Decimation methods are evaluated based on this metric and on direct comparison with reference images.

  16. Shapes and textures for rendering coral

    SciTech Connect

    Max, N.L. ); Wyvill, G. )

    1990-10-18

    A growth algorithm has been developed to build coral shapes out of a tree of spheres. A volume density defined by the spheres is contoured to give a soft object.'' The resulting contour surfaces are rendered by ray tracing, using a generalized volume texture to produce shading and bump mapped'' normal perturbations. 16 refs., 8 figs.

  17. Uncalibrated color

    NASA Astrophysics Data System (ADS)

    Moroney, Nathan

    2006-01-01

    Color calibration or the use of color measurement processes to characterize the color properties of a device or workflow is often expected or assumed for many color reproduction applications. However it is interesting to consider applications or situations in which color calibration is not as critical. In the first case it is possible to imagine an implicit color calibration resulting from a standardization or convergence of the colorant and substrate spectrum. In the second case it is possible to imagine cases where the device color variability is significantly less than the user color thresholds or expectations for color consistency. There are still general requirements for this form of pragmatic color but they are generally lower than for the higher end of digital color reproduction. Finally it is possible to imagine an implicit calibration that leverages in some way the highly accurate memory color for the hue of common objects. This scenario culminates with a challenge to create a natural capture calibration standard that does not require individual calibration, is spectrally diverse, is inexpensive and is environmentally friendly.

  18. Color realism and color science.

    PubMed

    Byrne, Alex; Hilbert, David R

    2003-02-01

    The target article is an attempt to make some progress on the problem of color realism. Are objects colored? And what is the nature of the color properties? We defend the view that physical objects (for instance, tomatoes, radishes, and rubies) are colored, and that colors are physical properties, specifically, types of reflectance. This is probably a minority opinion, at least among color scientists. Textbooks frequently claim that physical objects are not colored, and that the colors are "subjective" or "in the mind." The article has two other purposes: First, to introduce an interdisciplinary audience to some distinctively philosophical tools that are useful in tackling the problem of color realism and, second, to clarify the various positions and central arguments in the debate. The first part explains the problem of color realism and makes some useful distinctions. These distinctions are then used to expose various confusions that often prevent people from seeing that the issues are genuine and difficult, and that the problem of color realism ought to be of interest to anyone working in the field of color science. The second part explains the various leading answers to the problem of color realism, and (briefly) argues that all views other than our own have serious difficulties or are unmotivated. The third part explains and motivates our own view, that colors are types of reflectances and defends it against objections made in the recent literature that are often taken as fatal. PMID:14598439

  19. A multi-zoned white organic light-emitting diode with high CRI and low color temperature

    PubMed Central

    Zhang, Tao; He, Shou-Jie; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

    2016-01-01

    White organic light emitting diodes (WOLEDs) is becoming a new platform technology for a range of applications such as flat-panel displays, solid-state lightings etc., and are under intensive research. For general solid-state illumination applications, a WOLED’s color rendering index (CRI) and correlated color temperature (CCT) are two crucial parameters. This paper reports that WOLED device structures can be constructed using four stacked emission layers which independently emit lights at blue, green, yellow and red color respectively. The intensity of each emission layer is then engineered by funneling excitons to the targeted emission layer to achieve an ultrahigh 92 CRI at 5000 cd/m2, and to reduce CCT to below 2500 K. PMID:26842934

  20. A multi-zoned white organic light-emitting diode with high CRI and low color temperature

    NASA Astrophysics Data System (ADS)

    Zhang, Tao; He, Shou-Jie; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

    2016-02-01

    White organic light emitting diodes (WOLEDs) is becoming a new platform technology for a range of applications such as flat-panel displays, solid-state lightings etc., and are under intensive research. For general solid-state illumination applications, a WOLED’s color rendering index (CRI) and correlated color temperature (CCT) are two crucial parameters. This paper reports that WOLED device structures can be constructed using four stacked emission layers which independently emit lights at blue, green, yellow and red color respectively. The intensity of each emission layer is then engineered by funneling excitons to the targeted emission layer to achieve an ultrahigh 92 CRI at 5000 cd/m2, and to reduce CCT to below 2500 K.

  1. A multi-zoned white organic light-emitting diode with high CRI and low color temperature.

    PubMed

    Zhang, Tao; He, Shou-Jie; Wang, Deng-Ke; Jiang, Nan; Lu, Zheng-Hong

    2016-01-01

    White organic light emitting diodes (WOLEDs) is becoming a new platform technology for a range of applications such as flat-panel displays, solid-state lightings etc., and are under intensive research. For general solid-state illumination applications, a WOLED's color rendering index (CRI) and correlated color temperature (CCT) are two crucial parameters. This paper reports that WOLED device structures can be constructed using four stacked emission layers which independently emit lights at blue, green, yellow and red color respectively. The intensity of each emission layer is then engineered by funneling excitons to the targeted emission layer to achieve an ultrahigh 92 CRI at 5000 cd/m(2), and to reduce CCT to below 2500 K. PMID:26842934

  2. Color To Colorant Conversions In A Colorimetric Separation System

    NASA Astrophysics Data System (ADS)

    Holub, Richard; Kearsley, Wayne

    1990-06-01

    Within several years of establishment of the CIE's Standard Observer, Neugebauer based upon it a device-independent interpretation of ink mixture in halftone color reproduction. Despite limitations of the model, his approach is of fundamental importance at a time in which document preparation in distributed computing environments is coming of age. Fruition of this technology demands a device independent or colorimetric method for representing and rendering color. A commercial, digital system for implementing such an approach (Kodak Designmaster 8000) has been described and will be reviewed here with particular regard to the output of color imagery on four-color printers. Inversion of Neugebauer's model for conversion of color to device specific signals must be constrained by the color gamut of the output medium and the utilization of the black printer (Gray Component Replacement). The interaction of the black printer with the device gamut and its effect on image quality and metamerism will receive detailed consideration. It will be shown that colorimetry is a powerful tool in maintaining accurate color reproduction during substitution of black for chromatic components, but that properties of the colorants must also be considered in order to realize commercially acceptable GCR. Section 7 of the paper is an enumeration of summary conclusions.

  3. Multi-chip color variable LED spot modules

    NASA Astrophysics Data System (ADS)

    Hoelen, C.; Ansems, J.; Deurenberg, P.; Treurniet, T.; van Lier, E.; Chao, O.; Mercier, V.; Calon, G.; van Os, K.; Lijten, G.; Sondag-Huethorst, J.

    2005-09-01

    The unique features of light emitting diodes (LEDs) such as intrinsic color generation and relative low temperature operation enable completely new lighting concepts. The ongoing increase in performance of LEDs reaching efficacy levels of more than 30 lm/W for illumination grade white light with the promise of reaching over 75 lm/W makes them also applicable for higher luminous applications such as spot and flood lighting, accent lighting and architectural lighting. For the new lighting feature of ambiance creation, which requires at least variation of the color temperature of the light and preferably also selection of more saturated colors, LEDs are ideally suited. In this paper we report on the overall system aspects to color variable LED spot lighting and on the performance of prototype spot modules. Mixing of the light is performed within the lighting module by a combination of dense packing of red/amber, green and blue emitting dice, and light collimation with facetted optics and small angle diffusion, resulting in a homogeneous appearance of the light source and a color point inhomogeneity Δu'v' in the beam (>90% of total flux) of less than 0.01. A color rendering index (Ra8) of over 80 can be obtained over a large temperature and color temperature range with the 3-color system for a specific combination of 5 nm wide wavelength bins. In the prototype spot modules, between 9 and 14 dice are mounted on a common substrate and integrated with the primary collimating optics that is based on total internal reflection. Nominal power of the spot module is 10W. The average thermal resistance between the die junctions and the housing is 2 K/W. The optical efficiency of the module is 70%. The maximum luminous flux in the beam, which has a full width at half maximum (FWHM) of 20-25°, is about 200 lm. The system has thermal and optical sensors that provide the signals for a closed control loop to compensate for run-up and differential ageing effects. The resulting color

  4. Seeing Color

    ERIC Educational Resources Information Center

    Texley, Juliana

    2005-01-01

    Colors are powerful tools for engaging children, from the youngest years onward. We hang brightly patterned mobiles above their cribs and help them learn the names of colors as they begin to record their own ideas in pictures and words. Colors can also open the door to an invisible world of electromagnetism, even when children can barely imagine…

  5. Remote interactive direct volume rendering of AMR data

    SciTech Connect

    Kreylos, Oliver; Weber, Gunther H.; Bethel, E. Wes; Shalf, John M.; Hamann, Bernd; Joy, Kenneth I.

    2002-03-28

    We describe a framework for direct volume rendering of adaptive mesh refinement (AMR) data that operates directly on the hierarchical grid structure, without the need to resample data onto a single, uniform rectilinear grid. The framework can be used for a range of renderers optimized for particular hardware architectures: a hardware-assisted renderer for single-processor graphics workstations, and a massively parallel software-only renderer for supercomputers. It is also possible to use the framework for distributed rendering servers. By exploiting the multiresolution structure of AMR data, the hardware-assisted renderers can render large AMR data sets at interactive rates, even if the data is stored remotely.

  6. A rendering approach for stereoscopic web pages

    NASA Astrophysics Data System (ADS)

    Zhang, Jianlong; Wang, Wenmin; Wang, Ronggang; Chen, Qinshui

    2014-03-01

    Web technology provides a relatively easy way to generate contents for us to recognize the world, and with the development of stereoscopic display technology, the stereoscopic devices will become much more popular. The combination of web technology and stereoscopic display technology will bring revolutionary visual effect. The Stereoscopic 3D (S3D) web pages, in which text, image and video may have different depth, can be displayed on stereoscopic display devices. This paper presents the approach about how to render two viewing S3D web pages including text, images, widgets: first, an algorithm should be developed in order to display stereoscopic elements like text, widgets by using 2D graphic library; second, a method should be presented to render stereoscopic web page based on current framework of the browser; third, a rough solution is invented to fix the problem that comes out in the method.

  7. Remote rendering using vtk and vic.

    SciTech Connect

    Olson, R.; Papka, M.E.

    2000-09-19

    This paper presents a remote rendering application that involves the extension of the Visualization Toolkit (vtk) and the Video Conferencing Tool (vie) for use in remote rendering complete with interaction from the remote site using the vie user interface. Vtk is an open source C++ library, with Tel, Python, and Java bindings for computer graphics, image processing, and visualization [3]. Vtk provides a higher level of support, beyond the traditional low-level libraries, for creating visualization applications. Vtk includes algorithms to support the visualization of scalars, vectors, and tensors. Vic is a flexible tool built by Lawrence Berkeley National Laboratory for real-time video conferencing over the Internet [2]. Vie's user interface is built as Tcl/Tk script embedded in the applications. This allows developers to prototype changes to the interface in a simple and straightforward manner.

  8. A Task Adaptive parallel graphics renderer

    SciTech Connect

    Whitman, S.

    1992-12-21

    This paper presents a graphics renderer which incorporates new partitioning methodologies of memory and work for efficient execution on a parallel computer. The Task Adaptive domain decomposition scheme is an image space method involving dynamic partitioning of rectangular pixel area tasks. The author shows that this method requires little overhead, allows coherence within a parallel context, handles worst case scenarios effectively, and executes efficiently with little processor synchronization necessary. Previous research in the area of memory and work decompositions for graphics rendering has been primarily limited to simulation studies and little practical experience. The algorithm presented here has been implemented on a scalable distributed memory multiprocessor and tested on a variety of input scenes. The author presents a theoretical and practical analysis in order to contrast its predicted and actual success. The implementation analysis indicates that load imbalance is the major cause of performance degradation at the higher processor counts. Even so, on a variety of test scenes, an average rendering speedup of 79 was achieved utilizing 96 processors on the BBN TC2000 multiprocessor with a processor efficiency range of 66% to 94%.

  9. Color Categories and Color Appearance

    ERIC Educational Resources Information Center

    Webster, Michael A.; Kay, Paul

    2012-01-01

    We examined categorical effects in color appearance in two tasks, which in part differed in the extent to which color naming was explicitly required for the response. In one, we measured the effects of color differences on perceptual grouping for hues that spanned the blue-green boundary, to test whether chromatic differences across the boundary…

  10. Color Terms and Color Concepts

    ERIC Educational Resources Information Center

    Davidoff, Jules

    2006-01-01

    In their lead articles, both Kowalski and Zimiles (2006) and O'Hanlon and Roberson (2006) declare a general relation between color term knowledge and the ability to conceptually represent color. Kowalski and Zimiles, in particular, argue for a priority for the conceptual representation in color term acquisition. The complexities of the interaction…

  11. Pet fur color and texture classification

    NASA Astrophysics Data System (ADS)

    Yen, Jonathan; Mukherjee, Debarghar; Lim, SukHwan; Tretter, Daniel

    2007-01-01

    Object segmentation is important in image analysis for imaging tasks such as image rendering and image retrieval. Pet owners have been known to be quite vocal about how important it is to render their pets perfectly. We present here an algorithm for pet (mammal) fur color classification and an algorithm for pet (animal) fur texture classification. Per fur color classification can be applied as a necessary condition for identifying the regions in an image that may contain pets much like the skin tone classification for human flesh detection. As a result of the evolution, fur coloration of all mammals is caused by a natural organic pigment called Melanin and Melanin has only very limited color ranges. We have conducted a statistical analysis and concluded that mammal fur colors can be only in levels of gray or in two colors after the proper color quantization. This pet fur color classification algorithm has been applied for peteye detection. We also present here an algorithm for animal fur texture classification using the recently developed multi-resolution directional sub-band Contourlet transform. The experimental results are very promising as these transforms can identify regions of an image that may contain fur of mammals, scale of reptiles and feather of birds, etc. Combining the color and texture classification, one can have a set of strong classifiers for identifying possible animals in an image.

  12. Volume rendering segmented data using 3D textures: a practical approach for intra-operative visualization

    NASA Astrophysics Data System (ADS)

    Subramanian, Navneeth; Mullick, Rakesh; Vaidya, Vivek

    2006-03-01

    Volume rendering has high utility in visualization of segmented datasets. However, volume rendering of the segmented labels along with the original data causes undesirable intermixing/bleeding artifacts arising from interpolation at the sharp boundaries. This issue is further amplified in 3D textures based volume rendering due to the inaccessibility of the interpolation stage. We present an approach which helps minimize intermixing artifacts while maintaining the high performance of 3D texture based volume rendering - both of which are critical for intra-operative visualization. Our approach uses a 2D transfer function based classification scheme where label distinction is achieved through an encoding that generates unique gradient values for labels. This helps ensure that labelled voxels always map to distinct regions in the 2D transfer function, irrespective of interpolation. In contrast to previously reported algorithms, our algorithm does not require multiple passes for rendering and supports greater than 4 masks. It also allows for real-time modification of the colors/opacities of the segmented structures along with the original data. Additionally, these capabilities are available with minimal texture memory requirements amongst comparable algorithms. Results are presented on clinical and phantom data.

  13. Automatic Perceptual Color Map Generation for Realistic Volume Visualization

    PubMed Central

    Silverstein, Jonathan C.; Parsad, Nigel M.; Tsirline, Victor

    2008-01-01

    Advances in computed tomography imaging technology and inexpensive high performance computer graphics hardware are making high-resolution, full color (24-bit) volume visualizations commonplace. However, many of the color maps used in volume rendering provide questionable value in knowledge representation and are non-perceptual thus biasing data analysis or even obscuring information. These drawbacks, coupled with our need for realistic anatomical volume rendering for teaching and surgical planning, has motivated us to explore the auto-generation of color maps that combine natural colorization with the perceptual discriminating capacity of grayscale. As evidenced by the examples shown that have been created by the algorithm described, the merging of perceptually accurate and realistically colorized virtual anatomy appears to insightfully interpret and impartially enhance volume rendered patient data. PMID:18430609

  14. Does correlated color temperature affect the ability of humans to identify veins?

    PubMed

    Argyraki, Aikaterini; Clemmensen, Line Katrine Harder; Petersen, Paul Michael

    2016-01-01

    In the present study we provide empirical evidence and demonstrate statistically that white illumination settings can affect the human ability to identify veins in the inner hand vasculature. A special light-emitting diode lamp with high color rendering index (CRI 84-95) was developed and the effect of correlated color temperature was evaluated, in the range between 2600 and 5700 K at an illuminance of 40±9  lx on the ability of adult humans to identify veins. It is shown that the ability to identify veins can, on average, be increased up to 24% when white illumination settings that do not resemble incandescent light are applied. The illuminance reported together with the effect of white illumination settings on direct visual perception of biosamples are relevant for clinical investigations during the night. PMID:26831595

  15. Very low color-temperature organic light-emitting diodes for lighting at night

    NASA Astrophysics Data System (ADS)

    Jou, Jwo-Huei; Tang, Ming-Chun; Chen, Pin-Chu; Chen, Szu-Hao; Shen, Shih-Ming; Chen, Chien-Chih; Wang, Ching-Chiun; Chen, Chien-Tien

    2011-12-01

    Light sources with low color temperature (CT) are essential for their markedly less suppression effect on the secretion of melatonin, and high power efficiency is crucial for energy-saving. To provide visual comfort, the light source should also have a reasonably high color rendering index (CRI). In this report, we demonstrate the design and fabrication of low CT and high efficiency organic light-emitting diodes. The best resultant device exhibits a CT of 1,880 K, much lower than that of incandescent bulbs (2,000-2,500 K) and even as low as that of candles, (1,800-2,000 K), a beyond theoretical limit external quantum efficiency 22.7 %, and 36.0 lm/W at 100 cd/m 2. The high efficiency of the proposed device may be attributed to its interlayer, which helps effectively distribute the entering carriers into the available recombination zones.

  16. Color Analysis

    NASA Astrophysics Data System (ADS)

    Wrolstad, Ronald E.; Smith, Daniel E.

    Color, flavor, and texture are the three principal quality attributes that determine food acceptance, and color has a far greater influence on our judgment than most of us appreciate. We use color to determine if a banana is at our preferred ripeness level, and a discolored meat product can warn us that the product may be spoiled. The marketing departments of our food corporations know that, for their customers, the color must be "right." The University of California Davis scorecard for wine quality designates four points out of 20, or 20% of the total score, for color and appearance (1). Food scientists who establish quality control specifications for their product are very aware of the importance of color and appearance. While subjective visual assessment and use of visual color standards are still used in the food industry, instrumental color measurements are extensively employed. Objective measurement of color is desirable for both research and industrial applications, and the ruggedness, stability, and ease of use of today's color measurement instruments have resulted in their widespread adoption.

  17. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  18. a Cache Design Method for Spatial Information Visualization in 3d Real-Time Rendering Engine

    NASA Astrophysics Data System (ADS)

    Dai, X.; Xiong, H.; Zheng, X.

    2012-07-01

    A well-designed cache system has positive impacts on the 3D real-time rendering engine. As the amount of visualization data getting larger, the effects become more obvious. They are the base of the 3D real-time rendering engine to smoothly browsing through the data, which is out of the core memory, or from the internet. In this article, a new kind of caches which are based on multi threads and large file are introduced. The memory cache consists of three parts, the rendering cache, the pre-rendering cache and the elimination cache. The rendering cache stores the data that is rendering in the engine; the data that is dispatched according to the position of the view point in the horizontal and vertical directions is stored in the pre-rendering cache; the data that is eliminated from the previous cache is stored in the eliminate cache and is going to write to the disk cache. Multi large files are used in the disk cache. When a disk cache file size reaches the limit length(128M is the top in the experiment), no item will be eliminated from the file, but a new large cache file will be created. If the large file number is greater than the maximum number that is pre-set, the earliest file will be deleted from the disk. In this way, only one file is opened for writing and reading, and the rest are read-only so the disk cache can be used in a high asynchronous way. The size of the large file is limited in order to map to the core memory to save loading time. Multi-thread is used to update the cache data. The threads are used to load data to the rendering cache as soon as possible for rendering, to load data to the pre-rendering cache for rendering next few frames, and to load data to the elimination cache which is not necessary for the moment. In our experiment, two threads are designed. The first thread is to organize the memory cache according to the view point, and created two threads: the adding list and the deleting list, the adding list index the data that should be

  19. Biomimetics, color, and the arts

    NASA Astrophysics Data System (ADS)

    Schenk, Franziska

    2015-03-01

    Color as dramatic, dynamic and dazzling as the iridescent hues on the wings of certain butterflies has never been encountered in the art world. Unlike and unmatched by the chemical pigments of the artists' palette, this changeable color is created by transparent, colorless nanostructures that, as with prisms, diffract and reflect light to render spectral color visible. Until now, iridescent colors, by their very nature, have defied artists' best efforts to fully capture these rainbow hues. Now, for the first time, the artist and researcher Franziska Schenk employs latest nature-inspired color-shift technology to actually simulate the iridescence of butterflies and beetles on canvas. Crucially, studying the ingenious ways in which a range of such displays are created by insects has provided the artist with vital clues on how to adapt and adopt these challenging optical nano-materials for painting. And indeed, after years of meticulous and painstaking research both in the lab and studio, the desired effect is achieved. The resulting paintings, like an iridescent insect, do in fact fluctuate in perceived color - depending on the light and viewing angle. In tracing the artist's respective biomimetic approach, the paper not only provides an insight into the new color technology's evolution and innovative artistic possibilities, but also suggests what artists can learn from nature.

  20. [Hair colorants].

    PubMed

    Urbanek-Karłowska, B; Luks, E; Jedra, M; Kiss, E; Malanowska, M

    1997-01-01

    The properties, mode of action and its duration of the preparations used for hair dyeing are described, together with their chemical components, and also preparations of herbal origin. The chemical reactions are described in detail which lead the development of a color polymer occurring during hair dyeing. The studies are presented which are used for toxicological assessment of the raw materials which are the components of the colorants, and the list is included of hair colorants permitted for use in Poland. PMID:9562811

  1. Phosphor in glass with Eu3+ and Pr3+-doped silicate glasses for LED color conversion

    NASA Astrophysics Data System (ADS)

    Park, Hyun-A.; Lee, Yl Kwon; Im, Won Bin; Heo, Jong; Chung, Woon Jin

    2015-03-01

    Phosphor-in-glasses (PiGs) with rare earth (RE) doped SiO2-B2O3-RO glasses were prepared by embedding YAG:Ce3+ as the yellow phosphor. Eu3+ and Pr3+ were used to dope the glass, varying their concentrations in order to provide red emissions for possible chromaticity-control of white-light emitting diodes (WLEDs). The glass-to-phosphor mixing ratio was also varied to find the proper combination for color-controlled white LEDs. PiGs with RE-doped glasses were sintered at 750 °C and polished to 250 μm in thickness for blue LED color conversion. The photoluminescence spectra of the PiGs were monitored after they were mounted on commercial blue LED chips. Variation of color coordination, color rendering index and correlated color temperature were observed due to red emissions from the doped RE-ions. The spectral contribution of Eu3+ and Pr3+ ions to white LEDs under 450 nm LED excitation was discussed. The spatial distribution of phosphors within the glass matrix, and their possible interaction, was inspected by SEM. The thermal quenching effect was also investigated.

  2. Polar Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 3 May 2004 This nighttime visible color image was collected on January 1, 2003 during the Northern Summer season near the North Polar Troughs.

    This daytime visible color image was collected on September 4, 2002 during the Northern Spring season in Vastitas Borealis. The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude 79, Longitude 346 East (14 West). 19 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with

  3. Quantum Color

    ScienceCinema

    Lincoln, Don

    2016-07-16

    The idea of electric charges and electricity in general is a familiar one to the science savvy viewer. However, electromagnetism is but one of the four fundamental forces and not the strongest one. The strongest of the fundamental forces is called the strong nuclear force and it has its own associated charge. Physicists call this charge ?color? in analogy with the primary colors, although there is no real connection with actual color. In this video, Fermilab?s Dr. Don Lincoln explains why it is that we live in a colorful world.

  4. The Colors of Saturn

    NASA Astrophysics Data System (ADS)

    DeVogel, Kayla; Chanover, Nancy; Thelen, Alexander

    2015-11-01

    Very little is known about the coloring agents, or chromophores, that color the clouds of Saturn’s belts and zones. Although the clouds of Saturn are more muted in their coloration and do not exhibit the more striking variations seen among Jupiter’s belts, zones, and cyclonic storm features, the physical processes that render Saturn’s clouds a yellowish hue are likely similar to those at work on Jupiter. Thus, a comprehensive color study that includes both Jupiter and Saturn is warranted to advance our understanding of chromophores in the giant planet atmospheres. Here we report on our efforts to characterize the colors of Saturn’s clouds.This study involves the analysis of two imaging data sets: those from Cassini’s Imaging Science Subsystem (ISS), and Wide Field Planetary Camera 2 images taken with the Hubble Space Telescope (HST). The HST data were acquired in 1994, 1998, 2002 and 2004 using eleven different filters spanning 255-973 nm. After the images were photometrically and geometrically calibrated, we used them to create low resolution spectra for six different latitude regions: the Equatorial Zone, the Equatorial Belt, the South Equatorial Belt, the South Temperate Zone, the South Temperate Belt and the South South Temperate Belt. The Cassini ISS images were acquired in 2004 and 2011 using twelve different filters spanning 258-938 nm, and corresponding low resolution spectra of the same latitude regions were generated using the ISS images. We compare these low resolution spectra to Saturn’s full-disk spectrum (Karkoschka, E., 1994, Icarus 111, 174) to examine colors of discrete latitudes versus the full-disk spectrum of Saturn. The extensive temporal coverage afforded by the combination of the HST and ISS images will enable us to explore possible seasonal variations in Saturn’s cloud colors. Finally, we examine the color evolution of the major 2011 storm on Saturn using the ISS data.This work was supported by the Discovery Scholars Program in

  5. Anatomical annotation on vascular structure in volume rendered images.

    PubMed

    Jiang, Zhengang; Nimura, Yukitaka; Hayashi, Yuichiro; Kitasaka, Takayuki; Misawa, Kazunari; Fujiwara, Michitaka; Kajita, Yasukazu; Wakabayashi, Toshihiko; Mori, Kensaku

    2013-03-01

    The precise annotation of vascular structure is desired in computer-assisted systems to help surgeons identify each vessel branch. This paper proposes a method that annotates vessels on volume rendered images by rendering their names on them using a two-pass rendering process. In the first rendering pass, vessel surface models are generated using such properties as centerlines, radii, and running directions. Then the vessel names are drawn on the vessel surfaces. Finally, the vessel name images and the corresponding depth buffer are generated by a virtual camera at the viewpoint. In the second rendering pass, volume rendered images are generated by a ray casting volume rendering algorithm that considers the depth buffer generated in the first rendering pass. After the two-pass rendering is finished, an annotated image is generated by blending the volume rendered image with the surface rendered image. To confirm the effectiveness of our proposed method, we performed a computer-assisted system for the automated annotation of abdominal arteries. The experimental results show that vessel names can be drawn on the corresponding vessel surface in the volume rendered images at a computing cost that is nearly the same as that by volume rendering only. The proposed method has enormous potential to be adopted to annotate the vessels in the 3D medical images in clinical applications, such as image-guided surgery. PMID:23562139

  6. Colored Chaos

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 7 May 2004 This daytime visible color image was collected on May 30, 2002 during the Southern Fall season in Atlantis Chaos.

    The THEMIS VIS camera is capable of capturing color images of the martian surface using its five different color filters. In this mode of operation, the spatial resolution and coverage of the image must be reduced to accommodate the additional data volume produced from the use of multiple filters. To make a color image, three of the five filter images (each in grayscale) are selected. Each is contrast enhanced and then converted to a red, green, or blue intensity image. These three images are then combined to produce a full color, single image. Because the THEMIS color filters don't span the full range of colors seen by the human eye, a color THEMIS image does not represent true color. Also, because each single-filter image is contrast enhanced before inclusion in the three-color image, the apparent color variation of the scene is exaggerated. Nevertheless, the color variation that does appear is representative of some change in color, however subtle, in the actual scene. Note that the long edges of THEMIS color images typically contain color artifacts that do not represent surface variation.

    Image information: VIS instrument. Latitude -34.5, Longitude 183.6 East (176.4 West). 38 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of

  7. Acoustic-tactile rendering of visual information

    NASA Astrophysics Data System (ADS)

    Silva, Pubudu Madhawa; Pappas, Thrasyvoulos N.; Atkins, Joshua; West, James E.; Hartmann, William M.

    2012-03-01

    In previous work, we have proposed a dynamic, interactive system for conveying visual information via hearing and touch. The system is implemented with a touch screen that allows the user to interrogate a two-dimensional (2-D) object layout by active finger scanning while listening to spatialized auditory feedback. Sound is used as the primary source of information for object localization and identification, while touch is used both for pointing and for kinesthetic feedback. Our previous work considered shape and size perception of simple objects via hearing and touch. The focus of this paper is on the perception of a 2-D layout of simple objects with identical size and shape. We consider the selection and rendition of sounds for object identification and localization. We rely on the head-related transfer function for rendering sound directionality, and consider variations of sound intensity and tempo as two alternative approaches for rendering proximity. Subjective experiments with visually-blocked subjects are used to evaluate the effectiveness of the proposed approaches. Our results indicate that intensity outperforms tempo as a proximity cue, and that the overall system for conveying a 2-D layout is quite promising.

  8. Volume rendering of segmented image objects.

    PubMed

    Bullitt, Elizabeth; Aylward, Stephen R

    2002-08-01

    This paper describes a new method of combining ray-casting with segmentation. Volume rendering is performed at interactive rates on personal computers, and visualizations include both "superficial" ray-casting through a shell at each object's surface and "deep" ray-casting through the confines of each object. A feature of the approach is the option to smoothly and interactively dilate segmentation boundaries along all axes. This ability, when combined with selective "turning off" of extraneous image objects, can help clinicians detect and evaluate segmentation errors that may affect surgical planning. We describe both a method optimized for displaying tubular objects and a more general method applicable to objects of arbitrary geometry. In both cases, select three-dimensional points are projected onto a modified z buffer that records additional information about the projected objects. A subsequent step selectively volume renders only through the object volumes indicated by the z buffer. We describe how our approach differs from other reported methods for combining segmentation with ray-casting, and illustrate how our method can be useful in helping to detect segmentation errors. PMID:12472272

  9. A Multiresolution Image Cache for Volume Rendering

    SciTech Connect

    LaMar, E; Pascucci, V

    2003-02-27

    The authors discuss the techniques and implementation details of the shared-memory image caching system for volume visualization and iso-surface rendering. One of the goals of the system is to decouple image generation from image display. This is done by maintaining a set of impostors for interactive display while the production of the impostor imagery is performed by a set of parallel, background processes. The system introduces a caching basis that is free of the gap/overlap artifacts of earlier caching techniques. instead of placing impostors at fixed, pre-defined positions in world space, the technique is to adaptively place impostors relative to the camera viewpoint. The positions translate with the camera but stay aligned to the data; i.e., the positions translate, but do not rotate, with the camera. The viewing transformation is factored into a translation transformation and a rotation transformation. The impostor imagery is generated using just the translation transformation and visible impostors are displayed using just the rotation transformation. Displayed image quality is improved by increasing the number of impostors and the frequency that impostors are re-rendering is improved by decreasing the number of impostors.

  10. 6. Photocopy of architectural rendering off front facade, circa 1849. ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    6. Photocopy of architectural rendering off front facade, circa 1849. Original rendering at Fair Street Reformed Dutch Church, Kingston, New York. - Second Reformed Dutch Church, 209 Fair Street, Kingston, Ulster County, NY