Science.gov

Sample records for achromatic color perception

  1. Simultaneous contrast and gamut relativity in achromatic color perception.

    PubMed

    Vladusich, Tony

    2012-09-15

    Simultaneous contrast refers to the respective whitening or blackening of physically identical image regions surrounded by regions of low or high luminance, respectively. A common method of measuring the strength of this effect is achromatic color matching, in which subjects adjust the luminance of a target region to achieve an achromatic color match with another region. Here I present psychophysical data questioning the assumption--built into many models of achromatic color perception--that achromatic colors are represented as points in a one-dimensional (1D) perceptual space, or an absolute achromatic color gamut. I present an alternative model in which the achromatic color gamut corresponding to a target region is defined relatively, with respect to surround luminance. Different achromatic color gamuts in this model correspond to different 1D lines through a 2D perceptual space composed of blackness and whiteness dimensions. Each such line represents a unique gamut of achromatic colors ranging from black to white. I term this concept gamut relativity. Achromatic color matches made between targets surrounded by regions of different luminance are shown to reflect the relative perceptual distances between points lying on different gamut lines. The model suggests a novel geometrical approach to simultaneous contrast and achromatic color matching in terms of the vector summation of local luminance and contrast components, and sets the stage for a unified computational theory of achromatic color perception.

  2. Flexible color perception depending on the shape and positioning of achromatic contours

    PubMed Central

    Vergeer, Mark; Anstis, Stuart; van Lier, Rob

    2015-01-01

    In this study, we present several demonstrations of color averaging between luminance boundaries. In each of the demonstrations, different black outlines are superimposed on one and the same colored surface. Whereas perception without these outlines comprises a blurry colored gradient, superimposing the outlines leads to a much clearer binary color percept, with different colors perceived on each side of the boundary. These demonstrations show that the color of the perceived surfaces is flexible, depending on the exact shape of the outlines that define the surface, and that different positioning of the outlines can lead to different, distinct color percepts. We argue that the principle of color averaging described here is crucial for the brain in building a useful model of the distal world, in which differences within object surfaces are perceptually minimized, while differences between surfaces are perceptually enhanced. PMID:26042060

  3. The achromatic locus: effect of navigation direction in color space.

    PubMed

    Chauhan, Tushar; Perales, Esther; Xiao, Kaida; Hird, Emily; Karatzas, Dimosthenis; Wuerger, Sophie

    2014-01-24

    An achromatic stimulus is defined as a patch of light that is devoid of any hue. This is usually achieved by asking observers to adjust the stimulus such that it looks neither red nor green and at the same time neither yellow nor blue. Despite the theoretical and practical importance of the achromatic locus, little is known about the variability in these settings. The main purpose of the current study was to evaluate whether achromatic settings were dependent on the task of the observers, namely the navigation direction in color space. Observers could either adjust the test patch along the two chromatic axes in the CIE u*v* diagram or, alternatively, navigate along the unique-hue lines. Our main result is that the navigation method affects the reliability of these achromatic settings. Observers are able to make more reliable achromatic settings when adjusting the test patch along the directions defined by the four unique hues as opposed to navigating along the main axes in the commonly used CIE u*v* chromaticity plane. This result holds across different ambient viewing conditions (Dark, Daylight, Cool White Fluorescent) and different test luminance levels (5, 20, and 50 cd/m(2)). The reduced variability in the achromatic settings is consistent with the idea that internal color representations are more aligned with the unique-hue lines than the u* and v* axes.

  4. Lightness dependence of achromatic loci in color-appearance coordinates

    PubMed Central

    Kuriki, Ichiro

    2015-01-01

    Shifts in the appearance of color under different illuminant chromaticity are known to be incomplete, and fit nicely with a simple linear transformation of cone responses that aligns the achromatic points under two illuminants. Most chromaticity-transfer functions with von-Kries-like transformations use only one set of values to fit the color shifts from one illuminant to another. However, an achromatic point shifts its chromaticity depending on the lightness of the test stimulus. This lightness dependence of the achromatic-point locus is qualitatively similar to a phenomenon known as the Helson-Judd effect. The present study suggests that the lightness dependency of achromatic points appears to be a general trend, which is supported by the results from deriving the optimal von-Kries coefficients for different lightness levels that best fit the color shifts under a different illuminant chromaticity. Further, we report that such a lightness dependence of the achromatic-point loci can be represented simply as a straight line in coordinates defined using color-appearance models such as CIECAM when normalized for daylight. PMID:25713543

  5. Selection of achromatic and non-neutral colors to fill lacunae in frescoes guided by a variational model of perceived contrast

    NASA Astrophysics Data System (ADS)

    Grementieri, Luca; Provenzi, Edoardo

    2017-02-01

    Many ancient paintings, in particular frescoes, have some parts ruined by time and events. Sometimes one or more non-negligible regions are completely lost, leaving a blank that is called by restaurateurs a `lacuna'. The general restoration philosophy adopted in these cases is to paint the interior part of the lacuna with an achromatic or non-neutral uniform color carefully selected in order to minimize its overall perception. In this paper, we present a computational model, based on a well-established variational theory of color perception, that may facilitate the job of a restaurateur by providing both achromatic and non-neutral colors which minimize the local contrast with the surrounding parts of the fresco.

  6. Signals for color and achromatic contrast in the goldfish inner retina.

    PubMed

    Burkhardt, Dwight A

    2014-11-01

    A moving stimulus paradigm was designed to investigate color contrast encoding in the retina. Recently, this paradigm yielded suggestive evidence for color contrast encoding in zebrafish but the significance and generality remain uncertain since the properties of color coding in the zebrafish inner retina are largely unknown. Here, the question of color contrast is pursued in the goldfish retina where there is much accumulated evidence for retinal mechanisms of color vision and opponent color-coding, in particular. Recordings of a sensitive local field potential of the inner retina, the proximal negative response, were made in the intact, superfused retina in the light-adapted state. Responses to color contrast and achromatic contrast were analyzed by comparing responses to a green moving bar on green versus red backgrounds. The quantitative form of the irradiance/response curves was distinctly different under a range of conditions in 32 retinas, thereby providing robust evidence for red-green color contrast. The color contrast is based on successive contrast, occurs in the absence of overt color opponency, and clearly differs from previous findings in the goldfish retina for simultaneous color contrast mediated by color-opponent neurons. The form of the irradiance/response curves suggests that successive color contrast is particularly important when achromatic contrast is low, as often occurs in natural environments. The present results provide a parallel with the well-known principle of human color vision, first proposed by Kirschmann as the third law of color contrast, and may also have implications for the evolution of vertebrate color vision.

  7. Revisitation of the luminance conditions for the occurrence of the achromatic neon color spreading illusion.

    PubMed

    Bressan, P

    1993-07-01

    This paper develops the idea (Bressan, 1993) that neon spreading derives from the perceptual scissioning of ordinary assimilation color, a process identical to that occurring with nonillusory colors in phenomenal transparency. It is commonly held that the critical elements in achromatic neon spreading patterns must be of luminance intermediate between that of the embedding lines and of the background. The interpretation of neon spreading on the basis of color scissioning, however, predicts that neon spreading should also be observed for different luminance hierarchies, provided that these are compatible with transparency. This prediction found experimental support in the present work. The results suggest that (1) the widespread notion that chromatic and achromatic neon spreading must be mediated by separate mechanisms is unwarranted; (2) the widespread notion that color spreading in ordinary assimilation patterns and color spreading in neon patterns must be mediated by separate mechanisms is unwarranted; and (3) other than pointing to the way in which the overall organization of a scene affects the mode of color appearance, the neon spreading effect may not convey any extra theoretical relevance.

  8. A significant enhancement of color transition from an on-off type achromatic colorimetric nanosensor for highly sensitive multi-analyte detection with the naked eye.

    PubMed

    Heo, Jun Hyuk; Yi, Gyu Sung; Lee, Byoung Sang; Cho, Hui Hun; Lee, Jin Woong; Lee, Jung Heon

    2016-11-03

    Here, we report the development of an achromatic nanoparticle-based colorimetric sensor (achromatic nanosensor) with an on-off type color change that significantly enhances the color transition and increases the sensitivity of the sensor for naked-eye inspection. The achromatic nanosensor was prepared via a modified CMYK (CRYK) subtractive color model by combining DNA-functionalized gold nanoparticles (AuNPs-DNA), silver nanoparticles (AgNPs-DNA), and gold nanorods (AuNRs-DNA). The initially black-colored achromatic nanosensor not only allowed multiplexed detection by generating target-specific diverse color changes, but also improved the recognition of color changes by the naked eye. Thus, this on-off type color change enabled analysis near the limit of detection (LOD) with the naked eye. In addition, we developed a new image processing method adapted for this achromatic sensor. By quantifying the saturation value of the color images of the achromatic sensor, we could significantly amplify the color signal of the samples, which is difficult to achieve with general colorimetric sensors. The practical application of this achromatic nanosensor for biomarker detection was demonstrated with thrombin and platelet-derived growth factor (PDGF) in human blood plasma. These results provide a new sensing platform that is applicable to most NP-based colorimetric sensing systems for a wide range of applications, including biomolecular diagnosis, chemical pollutant sensing, environmental monitoring, etc.

  9. Plasmonic Color-Graded Nanosystems with Achromatic Subwavelength Architectures for Light Filtering and Advanced SERS Detection.

    PubMed

    Proietti Zaccaria, Remo; Bisio, Francesco; Das, Gobind; Maidecchi, Giulia; Caminale, Michael; Vu, Chinh Duc; De Angelis, Francesco; Di Fabrizio, Enzo; Toma, Andrea; Canepa, Maurizio

    2016-03-01

    Plasmonic color-graded systems are devices featuring a spatially variable plasmonic response over their surface. They are widely used as nanoscale color filters; their typical size is small enough to allow integration with miniaturized electronic circuits, paving the way to realize novel nanophotonic devices. Currently, most plasmonic color-graded systems are intrinsically discrete because their chromatic response exploits the tailored plasmon resonance of microarchitectures characterized by different size or geometry for each target color. Here, we report the realization of multifunctional plasmon-graded devices where continuously graded chromatic response is achieved by smoothly tuning the composition of the resonator material while simultaneously maintaining an achromatic nanoscale geometry. The result is a new class of versatile materials: we show their application as plasmonic filters with a potential pixel size smaller than half of the exciting wavelength but also as multiplexed surface-enhanced Raman spectroscopy (SERS) substrates. Many more implementations, such as photovoltaic efficiency boosters or color routers, await and will benefit from the low fabrication cost and intrinsic plasmonic flexibility of the presented systems.

  10. Perception of Fechner Illusory Colors in Alzheimer Disease Patients

    PubMed Central

    Kaubrys, Gintaras; Bukina, Vera; Bingelytė, Ieva; Taluntis, Vladas

    2016-01-01

    Background Alzheimer disease (AD) primarily affects cognition. A variety of visual disorders was established in AD. Fechner illusory colors are produced by a rotating disk with a black and white pattern. The purpose of our research was to explore the perception of illusory colors in AD. Material/Methods W recruited 40 AD patients (MMSE ≥14) and 40 normal controls (CG group) matched by age, education, gender in this prospective, cross-sectional, case-control study. An achromatic Benham’s disk attached to a device to control the speed and direction of rotation was used to produce illusory colors. Primary, secondary, and tertiary RGB system colors were used for matching of illusory and physical colors. Results Subjects in the AD group perceived less illusory colors in 5 arcs (p<0.05) of the 8 arcs assessed. The biggest difference was found between AD and CG groups for pure blue (χ2=26.87, p<0.001 clockwise, χ2=22.75, p<0.001 counter-clockwise). Groups did not differ in perception of pure yellow opponent colors (p>0.05). Mixed colors of the blue-yellow axis were perceived less often in AD, but more frequently than pure blue (#0000FF). The sequence of colors on Benham’s disk followed a complex pattern, different from the order of physical spectral colors and opponent processes-based colors. Conclusions AD patients retained reduced perception of illusory colors. The perception of pure blue illusory color is almost absent in AD. The asymmetrical shift to the yellow opponent is observed in AD with red prevailing over green constituent. This may indicate cortical rather than retinal impairment. PMID:27902677

  11. The Achromatic ‘Philosophical Zombie’, a Syndrome of Cerebral Achromatopsia with Color Anopsognosia

    PubMed Central

    Carota, Antonio; Calabrese, Pasquale

    2013-01-01

    We describe a patient with persistent cerebral achromatopsia occurring after bilateral occipital strokes. Blinded color recognition was assessed with a computerized experimental paradigm and the patient reported the degree of confidence in the response exactness on a visual percent scale. Color recognition was accurate and above chance (Fisher's exact test, p < 0.002). The degree of confidence in the answers showed a significant correlation with recognition scores (Spearman rank order correlation, p < 0.0001). These findings constitute the exceptional condition of what we called color anopsognosia (not knowing of seeing colors) and recall the theoretic figure of the ‘philosophical zombie’. However, the cognitive mechanisms of the dissociation between a subjective colorless vision and good performance for color naming still remain poorly understood. PMID:23687498

  12. The achromatic 'philosophical zombie', a syndrome of cerebral achromatopsia with color anopsognosia.

    PubMed

    Carota, Antonio; Calabrese, Pasquale

    2013-01-01

    We describe a patient with persistent cerebral achromatopsia occurring after bilateral occipital strokes. Blinded color recognition was assessed with a computerized experimental paradigm and the patient reported the degree of confidence in the response exactness on a visual percent scale. Color recognition was accurate and above chance (Fisher's exact test, p < 0.002). The degree of confidence in the answers showed a significant correlation with recognition scores (Spearman rank order correlation, p < 0.0001). These findings constitute the exceptional condition of what we called color anopsognosia (not knowing of seeing colors) and recall the theoretic figure of the 'philosophical zombie'. However, the cognitive mechanisms of the dissociation between a subjective colorless vision and good performance for color naming still remain poorly understood.

  13. What visual illusions tell us about underlying neural mechanisms and observer strategies for tackling the inverse problem of achromatic perception

    PubMed Central

    Blakeslee, Barbara; McCourt, Mark E.

    2015-01-01

    Research in lightness perception centers on understanding the prior assumptions and processing strategies the visual system uses to parse the retinal intensity distribution (the proximal stimulus) into the surface reflectance and illumination components of the scene (the distal stimulus—ground truth). It is agreed that the visual system must compare different regions of the visual image to solve this inverse problem; however, the nature of the comparisons and the mechanisms underlying them are topics of intense debate. Perceptual illusions are of value because they reveal important information about these visual processing mechanisms. We propose a framework for lightness research that resolves confusions and paradoxes in the literature, and provides insight into the mechanisms the visual system employs to tackle the inverse problem. The main idea is that much of the debate and confusion in the literature stems from the fact that lightness, defined as apparent reflectance, is underspecified and refers to three different types of judgments that are not comparable. Under stimulus conditions containing a visible illumination component, such as a shadow boundary, observers can distinguish and match three independent dimensions of achromatic experience: apparent intensity (brightness), apparent local intensity ratio (brightness-contrast), and apparent reflectance (lightness). In the absence of a visible illumination boundary, however, achromatic vision reduces to two dimensions and, depending on stimulus conditions and observer instructions, judgments of lightness are identical to judgments of brightness or brightness-contrast. Furthermore, because lightness judgments are based on different information under different conditions, they can differ greatly in their degree of difficulty and in their accuracy. This may, in part, explain the large variability in lightness constancy across studies. PMID:25954181

  14. Children's Color Perception in Relation to Habitat and Skin Color.

    ERIC Educational Resources Information Center

    Gaines, Rosslyn; Powell, Gloria J.

    1981-01-01

    Developmental color perception of 278 four- and eight-year-old Black and White children in three societies was examined in relation to the theories that proximity to the equator and that fundus pigmentation (as measured by skin color) reduce shortwave (blue-green) in comparison to long-wave perception. (Author/MP)

  15. Perceived duration of chromatic and achromatic light.

    PubMed

    Kojima, Haruyuki; Kawabata, Yasuhiro

    2012-01-15

    Luminance and color information are considered to be processed in parallel systems. The integration of information from these two separate systems is crucial for the visual system to produce a coherent percept. To investigate how luminance and color lights are perceived in time, we measured the perceived duration of light stimuli with and without colors in a paradigm involving simultaneous perception with presentation of two successive stimulus frames. Luminance contrast and color contrast of the stimuli were set with a chromatic substitution technique. In Experiment 1, the perceived duration of both chromatic stimuli and achromatic stimuli increased as the luminance contrast decreased. Experiment 2 tested if the duration of the percept was influenced by color contrast which was defined by colorimetric purity of the stimuli, when luminance contrast was set as low as practically possible. The result showed that the duration of the percept decreased with increasing color contrast of the stimuli. Moreover, Experiment 3 demonstrated that the trend of perceived duration was consistent with the four primary colors, provided that the effective color contrast of stimulus was corrected based on the contrast sensitivity to the color. These experiments indicate that, with a high luminance contrast level, perceived duration of a stimulus is predominantly defined by luminance contrast, whereas in low luminance contrast conditions, the duration depends on the color contrast. The perceived duration of color stimuli showed an "inverse color contrast effect", similar to the well-known "inverse intensity effect" for luminance stimuli. The similarities and the differences between the two systems, as well as their priorities in processing temporal information of visual stimuli are further discussed.

  16. Color Perception in Children with Autism

    ERIC Educational Resources Information Center

    Franklin, Anna; Sowden, Paul; Burley, Rachel; Notman, Leslie; Alder, Elizabeth

    2008-01-01

    This study examined whether color perception is atypical in children with autism. In experiment 1, accuracy of color memory and search was compared for children with autism and typically developing children matched on age and non-verbal cognitive ability. Children with autism were significantly less accurate at color memory and search than…

  17. The Role of Contrast in the Perception of Achromatic Transparency: Comment on Singh and Anderson (2002) and Anderson (2003)

    ERIC Educational Resources Information Center

    Albert, Marc K.

    2008-01-01

    M. Singh and B. L. Anderson proposed a perceptual theory of achromatic transparency in which the perceived transmittance of a perceived transparent filter is determined by the ratio of the Michelson contrast seen in the region of transparency to that of the background seen directly. Subsequently, B. L. Anderson, M. Singh, and J. Meng proposed that…

  18. Achromatic synesthesias - a functional magnetic resonance imaging study.

    PubMed

    Melero, H; Ríos-Lago, M; Peña-Melián, A; Álvarez-Linera, J

    2014-09-01

    Grapheme-color synesthetes experience consistent, automatic and idiosyncratic colors associated with specific letters and numbers. Frequently, these specific associations exhibit achromatic synesthetic qualities (e.g. white, black or gray). In this study, we have investigated for the first time the neural basis of achromatic synesthesias, their relationship to chromatic synesthesias and the achromatic congruency effect in order to understand not only synesthetic color but also other components of the synesthetic experience. To achieve this aim, functional magnetic resonance imaging experiments were performed in a group of associator grapheme-color synesthetes and matched controls who were stimulated with real chromatic and achromatic stimuli (Mondrians), and with letters and numbers that elicited different types of grapheme-color synesthesias (i.e. chromatic and achromatic inducers which elicited chromatic but also achromatic synesthesias, as well as congruent and incongruent ones). The information derived from the analysis of Mondrians and chromatic/achromatic synesthesias suggests that real and synesthetic colors/achromaticity do not fully share neural mechanisms. The whole-brain analysis of BOLD signals in response to the complete set of synesthetic inducers revealed that the functional peculiarities of the synesthetic brain are distributed, and reflect different components of the synesthetic experience: a perceptual component, an (attentional) feature binding component, and an emotional component. Additionally, the inclusion of achromatic experiences has provided new evidence in favor of the emotional binding theory, a line of interpretation which constitutes a bridge between grapheme-color synesthesia and other developmental modalities of the phenomenon.

  19. Color blindness and contrast perception in cuttlefish (Sepia officinalis) determined by a visual sensorimotor assay.

    PubMed

    Mäthger, Lydia M; Barbosa, Alexandra; Miner, Simon; Hanlon, Roger T

    2006-05-01

    We tested color perception based upon a robust behavioral response in which cuttlefish (Sepia officinalis) respond to visual stimuli (a black and white checkerboard) with a quantifiable, neurally controlled motor response (a body pattern). In the first experiment, we created 16 checkerboard substrates in which 16 grey shades (from white to black) were paired with one green shade (matched to the maximum absorption wavelength of S. officinalis' sole visual pigment, 492 nm), assuming that one of the grey shades would give a similar achromatic signal to the tested green. In the second experiment, we created a checkerboard using one blue and one yellow shade whose intensities were matched to the cuttlefish's visual system. In both assays it was tested whether cuttlefish would show disruptive coloration on these checkerboards, indicating their ability to distinguish checkers based solely on wavelength (i.e., color). Here, we show clearly that cuttlefish must be color blind, as they showed non-disruptive coloration on the checkerboards whose color intensities were matched to the Sepia visual system, suggesting that the substrates appeared to their eyes as uniform backgrounds. Furthermore, we show that cuttlefish are able to perceive objects in their background that differ in contrast by approximately 15%. This study adds support to previous reports that S. officinalis is color blind, yet the question of how cuttlefish achieve "color-blind camouflage" in chromatically rich environments still remains.

  20. Color Perception and Factor Analysis.

    ERIC Educational Resources Information Center

    Cartwright, Hugh

    1986-01-01

    Provides background theory and an experiment relating to chemometrics. Describes the phenomenon where solutions are dichromatic or dichromic. Discusses the difficulty students have in describing such solutions that appear to be several different colors at the same time. (TW)

  1. The effect of the color red on consuming food does not depend on achromatic (Michelson) contrast and extends to rubbing cream on the skin.

    PubMed

    Bruno, Nicola; Martani, Margherita; Corsini, Claudia; Oleari, Claudio

    2013-12-01

    Recent literature suggests that individuals may consume less food when this is served on red plates. We explored this intriguing effect in three experiments. Independent groups of participants were presented with constant amounts of popcorns, chocolate chips, or moisturizing cream, on red, blue, or white plates. They were asked to sample the foods (by tasting them) or the cream (by rubbing it on the hand and forearm) as they wished and to complete mock "sensory analysis" questionnaires. Results confirmed that red plates reduce taste-related consumption and extended this effect to the touch-related consumption of moisturizing cream. Suggesting that the effect was not due to a decrease in the consciously experienced appeal of products on red plates, overall appreciation of the foods or cream did not differ according to plate color. After careful photometric measures of the materials used for each food-plate pairing, we determined that food and cream consumption was not predicted by Michelson (achromatic) contrast. Although the origin of the intriguing effect of the color red on consumption remains unclear, our results may prove useful to future potential explanations.

  2. Neurophysiological Evidence for Categorical Perception of Color

    ERIC Educational Resources Information Center

    Holmes, Amanda; Franklin, Anna; Clifford, Alexandra; Davies, Ian

    2009-01-01

    The aim of this investigation was to examine the time course and the relative contributions of perceptual and post-perceptual processes to categorical perception (CP) of color. A visual oddball task was used with standard and deviant stimuli from same (within-category) or different (between-category) categories, with chromatic separations for…

  3. Motion and color analysis for animat perception

    SciTech Connect

    Rabie, T.F.; Terzopoulos, D.

    1996-12-31

    We propose novel gaze control algorithms for active perception in mobile autonomous agents with directable, foveated vision sensors. Our agents are realistic artificial animals, or animals, situated in physics-based virtual worlds. Their active perception systems continuously analyze photorealistic retinal image streams to glean information useful for controlling the animal`s eyes and body. The vision system computes optical flow and segments moving targets in the low-resolution visual periphery. It then matches segmented targets against mental models of colored objects of interest. The eyes saccade to increase acuity by foveating objects, The resulting sensorimotor control loop supports complex behaviors, such as predation.

  4. Synesthesia for Color Is Linked to Improved Color Perception but Reduced Motion Perception

    PubMed Central

    Banissy, Michael J.; Tester, Victoria; Muggleton, Neil G.; Janik, Agnieszka B.; Davenport, Aimee; Franklin, Anna; Walsh, Vincent; Ward, Jamie

    2013-01-01

    Synesthesia is a rare condition in which one property of a stimulus (e.g., shape) triggers a secondary percept (e.g., color) not typically associated with the first. Work on synesthesia has predominantly focused on confirming the authenticity of synesthetic experience, but much less research has been conducted to examine the extent to which synesthesia is linked to broader perceptual differences. In the research reported here, we examined whether synesthesia is associated with differences in color and motion processing by comparing these abilities in synesthetes who experience color as their evoked sensation with nonsynesthetic participants. We show that synesthesia for color is linked to facilitated color sensitivity but decreased motion sensitivity. These findings are discussed in relation to the neurocognitive mechanisms of synesthesia and interactions between color and motion processing in typical adults. PMID:24091549

  5. Synesthesia for color is linked to improved color perception but reduced motion perception.

    PubMed

    Banissy, Michael J; Tester, Victoria; Muggleton, Neil G; Janik, Agnieszka B; Davenport, Aimee; Franklin, Anna; Walsh, Vincent; Ward, Jamie

    2013-12-01

    Synesthesia is a rare condition in which one property of a stimulus (e.g., shape) triggers a secondary percept (e.g., color) not typically associated with the first. Work on synesthesia has predominantly focused on confirming the authenticity of synesthetic experience, but much less research has been conducted to examine the extent to which synesthesia is linked to broader perceptual differences. In the research reported here, we examined whether synesthesia is associated with differences in color and motion processing by comparing these abilities in synesthetes who experience color as their evoked sensation with nonsynesthetic participants. We show that synesthesia for color is linked to facilitated color sensitivity but decreased motion sensitivity. These findings are discussed in relation to the neurocognitive mechanisms of synesthesia and interactions between color and motion processing in typical adults.

  6. Broadband Achromatic Telecentric Lens

    NASA Technical Reports Server (NTRS)

    Mouroulis, Pantazis

    2007-01-01

    A new type of lens design features broadband achromatic performance as well as telecentricity, using a minimum number of spherical elements. With appropriate modifications, the lens design form can be tailored to cover the range of response of the focal-plane array, from Si (400-1,000 nm) to InGaAs (400-1,700 or 2,100 nm) or InSb/HgCdTe reaching to 2,500 nm. For reference, lenses typically are achromatized over the visible wavelength range of 480-650 nm. In remote sensing applications, there is a need for broadband achromatic telescopes, normally satisfied with mirror-based systems. However, mirror systems are not always feasible due to size or geometry restrictions. They also require expensive aspheric surfaces. Non-obscured mirror systems can be difficult to align and have a limited (essentially one-dimensional) field of view. Centrally obscured types have a two-dimensional but very limited field in addition to the obscuration. Telecentricity is a highly desirable property for matching typical spectrometer types, as well as for reducing the variation of the angle of incidence and cross-talk on the detector for simple camera types. This rotationally symmetric telescope with no obscuration and using spherical surfaces and selected glass types fills a need in the range of short focal lengths. It can be used as a compact front unit for a matched spectrometer, as an ultra-broadband camera objective lens, or as the optics of an integrated camera/spectrometer in which the wavelength information is obtained by the use of strip or linear variable filters on the focal plane array. This kind of camera and spectrometer system can find applications in remote sensing, as well as in-situ applications for geological mapping and characterization of minerals, ecological studies, and target detection and identification through spectral signatures. Commercially, the lens can be used in quality-control applications via spectral analysis. The lens design is based on the rear landscape

  7. Color Term Knowledge Does Not Affect Categorical Perception of Color in Toddlers

    ERIC Educational Resources Information Center

    Franklin, A.; Clifford, A.; Williamson, E.; Davies, I.

    2005-01-01

    Categorical perception of color is shown when colors from the same category are discriminated less easily than equivalently spaced colors that cross a category boundary. The current experiments tested various models of categorical perception. Experiment 1 tested for categorical responding in 2- to 4-year-olds, the age range for the onset…

  8. The role of color and attention-to-color in mirror-symmetry perception.

    PubMed

    Gheorghiu, Elena; Kingdom, Frederick A A; Remkes, Aaron; Li, Hyung-Chul O; Rainville, Stéphane

    2016-07-11

    The role of color in the visual perception of mirror-symmetry is controversial. Some reports support the existence of color-selective mirror-symmetry channels, others that mirror-symmetry perception is merely sensitive to color-correlations across the symmetry axis. Here we test between the two ideas. Stimuli consisted of colored Gaussian-blobs arranged either mirror-symmetrically or quasi-randomly. We used four arrangements: (1) 'segregated' - symmetric blobs were of one color, random blobs of the other color(s); (2) 'random-segregated' - as above but with the symmetric color randomly selected on each trial; (3) 'non-segregated' - symmetric blobs were of all colors in equal proportions, as were the random blobs; (4) 'anti-symmetric' - symmetric blobs were of opposite-color across the symmetry axis. We found: (a) near-chance levels for the anti-symmetric condition, suggesting that symmetry perception is sensitive to color-correlations across the symmetry axis; (b) similar performance for random-segregated and non-segregated conditions, giving no support to the idea that mirror-symmetry is color selective; (c) highest performance for the color-segregated condition, but only when the observer knew beforehand the symmetry color, suggesting that symmetry detection benefits from color-based attention. We conclude that mirror-symmetry detection mechanisms, while sensitive to color-correlations across the symmetry axis and subject to the benefits of attention-to-color, are not color selective.

  9. Subjective perception of natural scenes: the role of color

    NASA Astrophysics Data System (ADS)

    Bianchi-Berthouze, Nadia

    2003-01-01

    The subjective perception of colors has been extensively studied, with a focus on single colors or on combinations of a few colors. Not much has been done, however, to understand the subjective perception of colors in other contexts, where color is not a single feature. This is what the Kansei community in Japan has set itself to, by exploring subjective experiences of perceptions, and colors in particular, given its obvious influence on humans' emotional changes. The motivation is to create computational models of user visual perceptions, so that computers can be endowed with the ability to personalize visual aspects of their computational task, according to their user. Such a capability is hypothesized to be very important in fields such as printing, information search, design support, advertisement, etc. In this paper, we present our experimental results in the study of color as a contextual feature of images, rather than in isolation. The experiments aim at understanding the mechanisms linked to the personal perception of colors in complex images, and to understand the formation of color categories when labeling experiences related to color perception.

  10. The role of color and attention-to-color in mirror-symmetry perception

    PubMed Central

    Gheorghiu, Elena; Kingdom, Frederick A. A.; Remkes, Aaron; Li, Hyung-Chul O.; Rainville, Stéphane

    2016-01-01

    The role of color in the visual perception of mirror-symmetry is controversial. Some reports support the existence of color-selective mirror-symmetry channels, others that mirror-symmetry perception is merely sensitive to color-correlations across the symmetry axis. Here we test between the two ideas. Stimuli consisted of colored Gaussian-blobs arranged either mirror-symmetrically or quasi-randomly. We used four arrangements: (1) ‘segregated’ – symmetric blobs were of one color, random blobs of the other color(s); (2) ‘random-segregated’ – as above but with the symmetric color randomly selected on each trial; (3) ‘non-segregated’ – symmetric blobs were of all colors in equal proportions, as were the random blobs; (4) ‘anti-symmetric’ – symmetric blobs were of opposite-color across the symmetry axis. We found: (a) near-chance levels for the anti-symmetric condition, suggesting that symmetry perception is sensitive to color-correlations across the symmetry axis; (b) similar performance for random-segregated and non-segregated conditions, giving no support to the idea that mirror-symmetry is color selective; (c) highest performance for the color-segregated condition, but only when the observer knew beforehand the symmetry color, suggesting that symmetry detection benefits from color-based attention. We conclude that mirror-symmetry detection mechanisms, while sensitive to color-correlations across the symmetry axis and subject to the benefits of attention-to-color, are not color selective. PMID:27404804

  11. Simple color conversion method to perceptible images for color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Meguro, Mitsuhiko; Takahashi, Chihiro; Koga, Toshio

    2006-02-01

    In this paper, we propose a color conversion method for realizing barrier free systems for color-defective vision. Human beings are perceiving colors by a ratio of reaction values by three kinds of cones on the retina. The three cones have different sensitivity to a wavelength of light. Nevertheless, dichromats, who are lacking of one of the three cones, tends to be diffcult for discriminating colors of a certain combination. The proposed techniques make new images by converting color for creating perceptible combination of color. The proposed method has three parts of processes. Firstly, we do image segmentation based on the color space L*a*b*. Secondly, we judge whether mean colors of divided regions of the segmented image tend to be confusion or not by using confusion color loci and color vision models of the persons with color-defective vision. Finally, the proposed technique realizes the perceptible images for dichromats by changing the confusion color in several regions of images. We show how effectiveness of the method by some application results.

  12. Cross-modal, bidirectional priming in grapheme-color synesthesia.

    PubMed

    Paffen, Chris L E; Van der Smagt, Maarten J; Nijboer, Tanja C W

    2015-05-01

    Grapheme-color synesthetes perceive achromatic graphemes to be inherently colored. In this study grapheme-color synesthetes and non-synesthetes discriminated (1) the color of visual targets presented along with aurally presented digit primes, and (2) the identity of aurally presented digit targets presented with visual color primes. Reaction times to visual color targets were longer when the color of the target was incongruent with the synesthetic percept reported for the prime. Likewise, discriminating aurally presented digit targets took longer when the color of the prime was incongruent with the synesthetic percept for the target. These priming effects were absent in non-synesthetes. We conclude that binding between digits and colors in grapheme-color synesthetes can occur bidirectionally across senses. The results are in line with the idea that synesthesia is the result of linking inducing stimuli (e.g. digits) to synesthetic percepts (colors) at an abstract - supra-modal - conceptual level of processing.

  13. The influence of color on emotional perception of natural scenes.

    PubMed

    Codispoti, Maurizio; De Cesarei, Andrea; Ferrari, Vera

    2012-01-01

    Is color a critical factor when processing the emotional content of natural scenes? Under challenging perceptual conditions, such as when pictures are briefly presented, color might facilitate scene segmentation and/or function as a semantic cue via association with scene-relevant concepts (e.g., red and blood/injury). To clarify the influence of color on affective picture perception, we compared the late positive potentials (LPP) to color versus grayscale pictures, presented for very brief (24 ms) and longer (6 s) exposure durations. Results indicated that removing color information had no effect on the affective modulation of the LPP, regardless of exposure duration. These findings imply that the recognition of the emotional content of scenes, even when presented very briefly, does not critically rely on color information.

  14. Posthypnotic suggestion alters conscious color perception in an automatic manner.

    PubMed

    Kallio, Sakari; Koivisto, Mika

    2013-01-01

    The authors studied whether a posthypnotic suggestion to see a brief, masked target as gray can change the color experience of a hypnotic virtuoso. The visibility of the target was manipulated by varying the delay between the target and the mask that followed it. The virtuoso's subjective reports indicated that her conscious color experience was altered already at short delays between the target and the subsequent mask. The virtuoso's objectively measured pattern of responding under posthypnotic suggestion could not be mimicked either by control participants nor the virtuoso herself. Due to posthypnotic amnesia, the virtuoso was unaware of suggestions given during hypnosis. Importantly, the virtuoso could not alter her color perception without a hypnotic suggestion. These results suggest that hypnosis can affect even a highly automatic process such as color perception.

  15. The Achromatic Interfero Coronagraph

    NASA Astrophysics Data System (ADS)

    Rabbia, Yves; Gay, Jean; Rivet, Jean-Pierre

    2007-04-01

    We report on the Achromatic Interfero Coronagraph, a focal imaging device which aims at rejecting the energy contribution of a point-like source set on-axis, so as to make detectable its angularly-close environment (applicable to stellar environment: circumstellar matter, faint companions, planetary systems, but also conceivably to Active Galactic Nucleii and multiple asteroïds). With AIC, starlight rejection is based on destructive interference, which allows exploration of the star's neighbourhood at an angular resolution better than the diffraction limit of the hosting telescope. Thanks to the focus crossing property of light, rejection is achromatic thus yielding a large spectral bandwidth of work. Descriptions and comments are given regarding the principle, the device itself, the constraints and limitations, and the theoretical performance. Results are presented which demonstrate the close-sensing capability and which show images of a companion obtained in laboratory and ‘on the sky’ as well. A short pictorial description of the alternative AIC concepts, CIAXE and Open-Air CIAXE, currently under study, is given. To cite this article: Y. Rabbia et al., C. R. Physique 8 (2007).

  16. Surface color perception and equivalent illumination models.

    PubMed

    Brainard, David H; Maloney, Laurence T

    2011-05-02

    Vision provides information about the properties and identity of objects. The ease with which we perceive object properties belies the difficulty of the underlying information-processing task. In the case of object color, retinal information about object reflectance is confounded with information about the illumination as well as about the object's shape and pose. There is no obvious rule that allows transformation of the retinal image to a color representation that depends primarily on object surface reflectance. Under many circumstances, however, object color appearance is remarkably stable across scenes in which the object is viewed. Here, we review a line of experiments and theory that aim to understand how the visual system stabilizes object color appearance. Our emphasis is on models derived from explicit analysis of the computational problem of estimating the physical properties of illuminants and surfaces from the retinal image, and experiments that test these models. We argue that this approach has considerable promise for allowing generalization from simplified laboratory experiments to richer scenes that more closely approximate natural viewing. We discuss the relation between the work we review and other theoretical approaches available in the literature.

  17. Interference of verbal labels in color categorical perception

    NASA Astrophysics Data System (ADS)

    Yokoi, Kenji; Nishimori, Tomoaki; Saida, Shinya

    2008-11-01

    Previous studies demonstrated that color categorical perception (CP; better cross-category than within-category discrimination) was reduced by verbal interference, suggesting that CP is mediated by verbal labeling. Here, we examined chromatic generality and experience-dependency of verbal interference in CP using the Stroop effect. We employed a simultaneous two-alternative forced choice discrimination task. Congruent or incongruent words were presented prior to discrimination. In experiment 1, incongruent color names reduced CP regardless of color boundary pairs. Next, we used noncolor words that seemed to be associated with color through experience. The results showed that the tested noncolor words did not modify CP (experiment 2). However, combined presentation of color and shape produced Stroop interference (experiment 3). Our finding suggests that familiarity or mastery of categorized information through experience may be evaluated by verbal interference.

  18. Achromatic Interaction Point Design

    SciTech Connect

    Guimei Wang,, Yaroslav Derbenev, S.Alex Bogacz, P. Chevtsov, Andre Afanaciev, Charles Ankenbrandt, Valentin Ivanov, Rolland P. Johnson

    2009-05-01

    Designers of high-luminosity energy-frontier muon colliders must provide strong beam focusing in the interaction regions. However, the construction of a strong, aberration-free beam focus is difficult and space consuming, and long straight sections generate an off-site radiation problem due to muon decay neutrinos that interact as they leave the surface of the earth. Without some way to mitigate the neutrino radiation problem, the maximum c.m. energy of a muon collider will be limited to about 3.5 TeV. A new concept for achromatic low beta design is being developed, in which the interaction region telescope and optical correction elements, are installed in the bending arcs. The concept, formulated analytically, combines space economy, a preventative approach to compensation for aberrations, and a reduction of neutrino flux concentration. An analytical theory for the aberration-free, low beta, spatially compact insertion is being developed.

  19. Rod Contributions to Color Perception: Linear with Rod Contrast

    PubMed Central

    Cao, Dingcai; Pokorny, Joel; Smith, Vivianne C.; Zele, Andrew J.

    2008-01-01

    At mesopic light levels, an incremental change in rod activation causes changes in color appearance. In this study, we investigated how rod mediated changes in color perception varied as a function of the magnitude of the rod contrast. Rod-mediated changes in color appearance were assessed by matching them with cone-mediated color changes. A two-channel four-primary colorimeter allowed independent control of the rods and each of the L-, M- and S-cone photoreceptor types. At all light levels, rod contributions to inferred PC, KC and MC pathway mediated vision were linearly related to the rod incremental contrast. This linear relationship could be described by a model based on primate ganglion cell responses with the assumption that rod signals were conveyed via rod-cone gap junctions at mesopic light levels. PMID:18561973

  20. Color signal encoding for high dynamic range and wide color gamut based on human perception

    NASA Astrophysics Data System (ADS)

    Nezamabadi, Mahdi; Miller, Scott; Daly, Scott; Atkins, Robin

    2014-01-01

    A new EOTF based on human perception, called PQ (Perceptual Quantizer), was proposed in a previous work (SMPTE Mot. Imag. J 2013, 122:52-59) and its performance was evaluated for a wide range of luminance levels and encoding bitdepth values. This paper is an extension of that previous work to include the color aspects of the PQ signal encoding. The efficiency of the PQ encoding and bit-depth requirements were evaluated and compared for standard color gamuts of Rec 709 (SRGB), and the wide color gamuts of Rec 2020, P3, and ACES for a variety of signal representations as RGB, YCbCr, and XYZ. In a selected color space for any potential local gray level 26 color samples were simulated by deviating one quantization step from the original color in each signal dimension. The quantization step sizes were simulated based on the PQ and gamma curves for different bit-depth values and luminance ranges for each of the color gamut spaces and signal representations. Color differences between the gray field and the simulated color samples were computed using CIE DE2000 color difference equation. The maximum color difference values (quantization error) were used as a metric to evaluate the performance of the corresponding EOTF curve. Extended color gamuts were found to require more bits to maintain low quantization error. Extended dynamic range required fewer additional bits in to maintain quantization error. Regarding the visual detection thresholds, the minimum bit-depth required by the PQ and gamma encodings are evaluated and compared through visual experiments.

  1. Surface color perception under two illuminants: the second illuminant reduces color constancy

    NASA Technical Reports Server (NTRS)

    Yang, Joong Nam; Shevell, Steven K.

    2003-01-01

    This study investigates color perception in a scene with two different illuminants. The two illuminants, in opposite corners, simultaneously shine on a (simulated) scene with an opaque dividing wall, which controls how much of the scene is illuminated by each source. In the first experiment, the height of the dividing wall was varied. This changed the amount of each illuminant reaching objects on the opposite side of the wall. Results showed that the degree of color constancy decreased when a region on one side of the wall had cues to both illuminants, suggesting that cues from the second illuminant are detrimental to color constancy. In a later experiment, color constancy was found to improve when the specular highlight cues from the second illuminant were altered to be consistent with the first illuminant. This corroborates the influence of specular highlights in surface color perception, and suggests that the reduced color constancy in the first experiment is due to the inconsistent, though physically correct, cues from the two illuminants.

  2. Working Memory Is Related to Perceptual Processing: A Case from Color Perception

    ERIC Educational Resources Information Center

    Allen, Elizabeth C.; Beilock, Sian L.; Shevell, Steven K.

    2011-01-01

    We explored the relation between individual differences in working memory (WM) and color constancy, the phenomenon of color perception that allows us to perceive the color of an object as relatively stable under changes in illumination. Successive color constancy (measured by first viewing a colored surface under a particular illumination and…

  3. Asymmetries in blue-yellow color perception and in the color of 'the dress'.

    PubMed

    Winkler, Alissa D; Spillmann, Lothar; Werner, John S; Webster, Michael A

    2015-06-29

    The perception of color poses daunting challenges, because the light spectrum reaching the eye depends on both the reflectance of objects and the spectrum of the illuminating light source. Solving this problem requires sophisticated inferences about the properties of lighting and surfaces, and many striking examples of 'color constancy' illustrate how our vision compensates for variations in illumination to estimate the color of objects (for example [1-3]). We discovered a novel property of color perception and constancy, involving how we experience shades of blue versus yellow. We found that surfaces are much more likely to be perceived as white or gray when their color is varied along bluish directions, compared with equivalent variations along yellowish (or reddish or greenish) directions. This selective bias may reflect a tendency to attribute bluish tints to the illuminant rather than the object, consistent with an inference that indirect lighting from the sky and in shadows tends to be bluish. The blue-yellow asymmetry has striking effects on the appearance of images when their colors are reversed, turning white to yellow and silver to gold, and helps account for the variation among observers in the colors experienced in 'the dress' image that recently consumed the internet. Observers variously describe the dress as blue-black or white-gold, and this has been explained by whether the dress appears to be in direct lighting or shade (for example [5]). We show that these individual differences and potential lighting interpretations also depend on the special ambiguity of blue, for simply reversing the image colors causes almost all observers to report the lighter stripes as yellowish.

  4. Categorical perception of color: evidence from secondary category boundary

    PubMed Central

    Al-rasheed, Abdulrahman Saud

    2015-01-01

    Despite a plethora of behavioral research exploring the phenomenon of color categorical perception (CP) known as “better discrimination between pair of colors stimuli from different categories and pair of colors stimuli from the same category even when the stimulus differences between the pairs of stimuli are equal”, most of the evidence for the CP of color was derived from Roman or top-to-down script readers and very rarely from right-to-left script readers in primary category. To date, no studies of color CP have been conducted on right-to-left script readers in secondary category boundary to support this theory. Three experiments have been conducted: Experiments 1 and 2 established the Arabic blue–purple secondary category boundary, and Experiment 3 tested the CP of color in the blue–purple category boundary. Sixty participants (30 men and 30 women) took part in this study. All spoke Arabic as their first language, and all were undergraduate or postgraduate students at King Saud University. Their ages ranged from 18–35 years with a mean age of 21.9 years (SD =5.2). The result indicated that for Experiments 1 and 2, it appeared that the Arabic blue–purple category boundary was approximately 10PB and it is in the same location as for English. For Experiment 3, reaction times in the between-categories condition were significantly faster than those in the within-category condition; this suggested that CP of color was shown in the Arabic’s blue–purple secondary category boundary. PMID:26648764

  5. A reinterpretation of transparency perception in terms of gamut relativity.

    PubMed

    Vladusich, Tony

    2013-03-01

    Classical approaches to transparency perception assume that transparency constitutes a perceptual dimension corresponding to the physical dimension of transmittance. Here I present an alternative theory, termed gamut relativity, that naturally explains key aspects of transparency perception. Rather than being computed as values along a perceptual dimension corresponding to transmittance, gamut relativity postulates that transparency is built directly into the fabric of the visual system's representation of surface color. The theory, originally developed to explain properties of brightness and lightness perception, proposes how the relativity of the achromatic color gamut in a perceptual blackness-whiteness space underlies the representation of foreground and background surface layers. Whereas brightness and lightness perception were previously reanalyzed in terms of the relativity of the achromatic color gamut with respect to illumination level, transparency perception is here reinterpreted in terms of relativity with respect to physical transmittance. The relativity of the achromatic color gamut thus emerges as a fundamental computational principle underlying surface perception. A duality theorem relates the definition of transparency provided in gamut relativity with the classical definition underlying the physical blending models of computer graphics.

  6. Compaction managed mirror bend achromat

    DOEpatents

    Douglas, David

    2005-10-18

    A method for controlling the momentum compaction in a beam of charged particles. The method includes a compaction-managed mirror bend achromat (CMMBA) that provides a beamline design that retains the large momentum acceptance of a conventional mirror bend achromat. The CMMBA also provides the ability to tailor the system momentum compaction spectrum as desired for specific applications. The CMMBA enables magnetostatic management of the longitudinal phase space in Energy Recovery Linacs (ERLs) thereby alleviating the need for harmonic linearization of the RF waveform.

  7. Adjustable hybrid diffractive/refractive achromatic lens

    PubMed Central

    Valley, Pouria; Savidis, Nickolaos; Schwiegerling, Jim; Dodge, Mohammad Reza; Peyman, Gholam; Peyghambarian, N.

    2011-01-01

    We demonstrate a variable focal length achromatic lens that consists of a flat liquid crystal diffractive lens and a pressure-controlled fluidic refractive lens. The diffractive lens is composed of a flat binary Fresnel zone structure and a thin liquid crystal layer, producing high efficiency and millisecond switching times while applying a low ac voltage input. The focusing power of the diffractive lens is adjusted by electrically modifying the sub-zones and re-establishing phase wrapping points. The refractive lens includes a fluid chamber with a flat glass surface and an opposing elastic polydimethylsiloxane (PDMS) membrane surface. Inserting fluid volume through a pump system into the clear aperture region alters the membrane curvature and adjusts the refractive lens’ focal position. Primary chromatic aberration is remarkably reduced through the coupling of the fluidic and diffractive lenses at selected focal lengths. Potential applications include miniature color imaging systems, medical and ophthalmic devices, or any design that utilizes variable focal length achromats. PMID:21503055

  8. The Role of Perception, Language, and Preference in the Developmental Acquisition of Basic Color Terms

    ERIC Educational Resources Information Center

    Pitchford, N. J.; Mullen, K. T.

    2005-01-01

    When learning basic color vocabulary, young children show a selective delay in the acquisition of brown and gray relative to other basic color terms. In this study, we first establish the robustness of this finding and then investigate the extent to which perception, language, and color preference may influence color conceptualization.…

  9. Effects of color combination and ambient illumination on visual perception time with TFT-LCD.

    PubMed

    Lin, Chin-Chiuan; Huang, Kuo-Chen

    2009-10-01

    An empirical study was carried out to examine the effects of color combination and ambient illumination on visual perception time using TFT-LCD. The effect of color combination was broken down into two subfactors, luminance contrast ratio and chromaticity contrast. Analysis indicated that the luminance contrast ratio and ambient illumination had significant, though small effects on visual perception. Visual perception time was better at high luminance contrast ratio than at low luminance contrast ratio. Visual perception time under normal ambient illumination was better than at other ambient illumination levels, although the stimulus color had a confounding effect on visual perception time. In general, visual perception time was better for the primary colors than the middle-point colors. Based on the results, normal ambient illumination level and high luminance contrast ratio seemed to be the optimal choice for design of workplace with video display terminals TFT-LCD.

  10. Effects of motion and configural complexity on color transparency perception.

    PubMed

    Gerardin, Peggy; Roud, Philippe; Süsstrunk, Sabine; Knoblauch, Kenneth

    2006-01-01

    We tested whether motion and configural complexity affect perceived transparency. A series of five coherent chromatic transformations in color space was applied across a figure: translation, convergence, shear, divergence and rotation. The stimuli consisted of a bipartite or a checkerboard configuration (10 x 10 degrees), with a central static or moving overlay (5 x 5 degrees). Three different luminance conditions (the plane of chromatic transformation oriented toward higher, lower, or equal luminances) were also tested for each of three modulation depths. For each stimulus, the observer judged whether the overlay appeared transparent or not. The main results indicated an interaction between the type of chromatic transformation and stimulus motion and complexity. For example, convergences are judged to appear transparent significantly more often when motion is added for bipartite configurations, or when they are generated in a checkerboard configuration. Surprisingly, shears that have been reported to appear opaque, are more frequently reported to appear transparent with short vector lengths and when combined with motion. Other transformations are also affected by motion, although the effectiveness of figural complexity on transparency seems to depend on both the type of color shifts and the presence of motion. The results indicate that adding motion and stimulus complexity are not necessarily neutral with respect to the chromatic shifts evoking transparency. Thus, studies that have used motion to enhance transparency may yield different results about the color shifts supporting transparency perception from those that did not. The same might be supposed for stimulus complexity under some conditions.

  11. Color synesthesia. Insight into perception, emotion, and consciousness

    PubMed Central

    Safran, Avinoam B.; Sanda, Nicolae

    2015-01-01

    Purpose of review Synesthesia is an extraordinary perceptual phenomenon, in which individuals experience unusual percepts elicited by the activation of an unrelated sensory modality or by a cognitive process. Emotional reactions are commonly associated. The condition prompted philosophical debates on the nature of perception and impacted the course of art history. It recently generated a considerable interest among neuroscientists, but its clinical significance apparently remains underevaluated. This review focuses on the recent studies regarding variants of color synesthesia, the commonest form of the condition. Recent findings Synesthesia is commonly classified as developmental and acquired. Developmental forms predispose to changes in primary sensory processing and cognitive functions, usually with better performances in certain aspects and worse in others, and to heightened creativity. Acquired forms of synesthesia commonly arise from drug ingestion or neurological disorders, including thalamic lesions and sensory deprivation (e.g., blindness). Cerebral exploration using structural and functional imaging has demonstrated distinct patterns in cortical activation and brain connectivity for controls and synesthetes. Artworks of affected painters are most illustrative of the nature of synesthetic experiences. Summary Results of the recent investigations on synesthesia offered a remarkable insight into the mechanisms of perception, emotion and consciousness, and deserve attention both from neuroscientists and from clinicians. PMID:25545055

  12. Physical Interpretation of Neugebauer Equations and Applications for Achromatic Synthesis

    NASA Astrophysics Data System (ADS)

    Kita, Shinji

    1990-06-01

    As Lambert-Beer's Law in density modulation images, Neugebauer Equations are the basic equation for color reproduction of dot modulation images. Its significance increases with the advance of digital color printing technology. Its' applications have been diversely enlarging to identify the relationship between dot allocation and color gamut', to forecast reproduced color2, and to discuss the achromatic synthesis in principle3, 4. As well known, its principle is that "color is reproduced by averaging additive color mixture of basic 8 colors' area and stimulus determined statistically by the Demichel's law" . The significant assumption here is "the independency of each color area", that is, the coverage and color stimulus of each color area are not influenced by those of neighbor. However, in an actual dot modulation image, optical diffusion and mixture occur within image as known as Yule-Nielsen's effect (Y-N effect). Therefore, the former assumption cannot be adapted on actual images. Since various marking technologies have their own optical diffusion and mixture respectively due to their marking principle and image structure, it seems that an overall comprehension for color reproduction of these images is required from these technologies. And besides, reconstruction of color reproduction theory including density modulation images will be more necessary in future. For this purpose, new theoretical approach adding Y-N effect to Neugebauer equations might be indispensable . From the viewpoint, this paper introduces the full-color image structure models which quantifies optical diffusion and mixture within recorded image and mentions the physical interpretation of Y-N effect in full-color image. Next, by using Neugebauer equations with Y-N effect6, we analyze the achromatic synthesis and propose the theoretical method for black determination applicable to all image formation, through density modulation to completely binary image.

  13. Crepuscular and nocturnal illumination and its effects on color perception by the nocturnal hawkmoth Deilephila elpenor.

    PubMed

    Johnsen, Sönke; Kelber, Almut; Warrant, Eric; Sweeney, Alison M; Widder, Edith A; Lee, Raymond L; Hernández-Andrés, Javier

    2006-03-01

    Recent studies have shown that certain nocturnal insect and vertebrate species have true color vision under nocturnal illumination. Thus, their vision is potentially affected by changes in the spectral quality of twilight and nocturnal illumination, due to the presence or absence of the moon, artificial light pollution and other factors. We investigated this in the following manner. First we measured the spectral irradiance (from 300 to 700 nm) during the day, sunset, twilight, full moon, new moon, and in the presence of high levels of light pollution. The spectra were then converted to both human-based chromaticities and to relative quantum catches for the nocturnal hawkmoth Deilephila elpenor, which has color vision. The reflectance spectra of various flowers and leaves and the red hindwings of D. elpenor were also converted to chromaticities and relative quantum catches. Finally, the achromatic and chromatic contrasts (with and without von Kries color constancy) of the flowers and hindwings against a leaf background were determined under the various lighting environments. The twilight and nocturnal illuminants were substantially different from each other, resulting in significantly different contrasts. The addition of von Kries color constancy significantly reduced the effect of changing illuminants on chromatic contrast, suggesting that, even in this light-limited environment, the ability of color vision to provide reliable signals under changing illuminants may offset the concurrent threefold decrease in sensitivity and spatial resolution. Given this, color vision may be more common in crepuscular and nocturnal species than previously considered.

  14. Does sadness impair color perception? Flawed evidence and faulty methods

    PubMed Central

    Holcombe, Alex O.; Brown, Nicholas J. L.; Goodbourn, Patrick T.; Etz, Alexander; Geukes, Sebastian

    2016-01-01

    In their 2015 paper, Thorstenson, Pazda, and Elliot offered evidence from two experiments that perception of colors on the blue–yellow axis was impaired if the participants had watched a sad movie clip, compared to participants who watched clips designed to induce a happy or neutral mood. Subsequently, these authors retracted their article, citing a mistake in their statistical analyses and a problem with the data in one of their experiments. Here, we discuss a number of other methodological problems with Thorstenson et al.’s experimental design, and also demonstrate that the problems with the data go beyond what these authors reported. We conclude that repeating one of the two experiments, with the minor revisions proposed by Thorstenson et al., will not be sufficient to address the problems with this work. PMID:27606051

  15. Achromatic and uncoupled medical gantry

    DOEpatents

    Tsoupas, Nicholaos; Kayran, Dmitry; Litvinenko, Vladimir; MacKay, William W.

    2011-11-22

    A medical gantry that focus the beam from the beginning of the gantry to the exit of the gantry independent of the rotation angle of the gantry by keeping the beam achromatic and uncoupled, thus, avoiding the use of collimators or rotators, or additional equipment to control the beam divergence, which may cause beam intensity loss or additional time in irradiation of the patient, or disadvantageously increase the overall gantry size inapplicable for the use in the medical treatment facility.

  16. Prediction of object detection, recognition, and identification [DRI] ranges at color scene images based on quantifying human color contrast perception

    NASA Astrophysics Data System (ADS)

    Pinsky, Ephi; Levin, Ilia; Yaron, Ofer

    2016-10-01

    We propose a novel approach to predict, for specified color imaging system and for objects with known characteristics, their detection, recognition, identification (DRI) ranges in a colored dynamic scene, based on quantifying the human color contrast perception. The method refers to the well established L*a*b*, 3D color space. The nonlinear relations of this space are intended to mimic the nonlinear response of the human eye. The metrics of L*a*b* color space is such that the Euclidian distance between any two colors in this space is approximately proportional to the color contrast as perceived by the human eye/brain. The result of this metrics leads to the outcome that color contrast of any two points is always greater (or equal) than their equivalent grey scale contrast. This meets our sense that looking on a colored image, contrast is superior to the gray scale contrast of the same image. Yet, color loss by scattering at very long ranges should be considered as well. The color contrast derived from the distance between the colored object pixels and to the nearby colored background pixels, as derived from the L*a*b* color space metrics, is expressed in terms of gray scale contrast. This contrast replaces the original standard gray scale contrast component of that image. As expected, the resulted DRI ranges are, in most cases, larger than those predicted by the standard gray scale image. Upon further elaboration and validation of this method, it may be combined with the next versions of the well accepted TRM codes for DRI predictions. Consistent prediction of DRI ranges implies a careful evaluation of the object and background color contrast reduction along the range. Clearly, additional processing for reconstructing the objects and background true colors and hence the color contrast along the range, will further increase the DRI ranges.

  17. The elementary representation of spatial and color vision in the human retina

    PubMed Central

    Sabesan, Ramkumar; Schmidt, Brian P.; Tuten, William S.; Roorda, Austin

    2016-01-01

    The retina is the most accessible element of the central nervous system for linking behavior to the activity of isolated neurons. We unraveled behavior at the elementary level of single input units—the visual sensation generated by stimulating individual long (L), middle (M), and short (S) wavelength–sensitive cones with light. Spectrally identified cones near the fovea of human observers were targeted with small spots of light, and the type, proportion, and repeatability of the elicited sensations were recorded. Two distinct populations of cones were observed: a smaller group predominantly associated with signaling chromatic sensations and a second, more numerous population linked to achromatic percepts. Red and green sensations were mainly driven by L- and M-cones, respectively, although both cone types elicited achromatic percepts. Sensations generated by cones were rarely stochastic; rather, they were consistent over many months and were dominated by one specific perceptual category. Cones lying in the midst of a pure spectrally opponent neighborhood, an arrangement purported to be most efficient in producing chromatic signals in downstream neurons, were no more likely to signal chromatic percepts. Overall, the results are consistent with the idea that the nervous system encodes high-resolution achromatic information and lower-resolution color signals in separate pathways that emerge as early as the first synapse. The lower proportion of cones eliciting color sensations may reflect a lack of evolutionary pressure for the chromatic system to be as fine-grained as the high-acuity achromatic system. PMID:27652339

  18. Synesthetic grapheme-color percepts exist for newly encountered Hebrew, Devanagari, Armenian and Cyrillic graphemes.

    PubMed

    Blair, Christopher David; Berryhill, Marian E

    2013-09-01

    Grapheme-color synesthetes experience color, not physically present, when viewing symbols. Synesthetes cannot remember learning these associations. Must synesthetic percepts be formed during a sensitive period? Can they form later and be consistent? What determines their nature? We tested grapheme-color synesthete, MC2, before, during and after she studied Hindi abroad. We investigated whether novel graphemes elicited synesthetic percepts, changed with familiarity, and/or benefited from phonemic information. MC2 reported color percepts to novel Devanagari and Hebrew graphemes. MC2 monitored these percepts over 6months in a Hindi-speaking environment. MC2 and synesthete DN, reported synesthetic percepts for Armenian graphemes, or Cyrillic graphemes+phonemes over time. Synesthetes, not controls, reported color percepts for novel graphemes that gained consistency over time. Phonemic information did not enhance consistency. Thus, synesthetes can form and consolidate percepts to novel graphemes as adults. These percepts may depend on pre-existing grapheme-color relationships but they can flexibly shift with familiarity.

  19. Context-dependent judgments of color that might allow color constancy in scenes with multiple regions of illumination.

    PubMed

    Lee, R J; Smithson, H E

    2012-02-01

    For a color-constant observer, a change in the spectral composition of the illumination is accompanied by a corresponding change in the chromaticity associated with an achromatic percept. However, maintaining color constancy for different regions of illumination within a scene implies the maintenance of multiple perceptual references. We investigated the features of a scene that enable the maintenance of separate perceptual references for two displaced but overlapping chromaticity distributions. The time-averaged, retinotopically localized stimulus was the primary determinant of color appearance judgments. However, spatial separation of test samples additionally served as a symbolic cue that allowed observers to maintain two separate perceptual references.

  20. [Pigment method to train color vision in the rehabilitation of railway workers with congenital disorders of color perception].

    PubMed

    Sosnova, T L; Baranova, E L; Bukhareva, E A

    1995-01-01

    The authors elaborated an effective method to master color vision through pigment tables. The method enables subnormal trichromats to normalize or improve colors perception and relieve existing disorders. The training course for deuteranomalopia "C" patients should comprise 8-10 procedures, that for deuteranomalopia "B" and protanopia "C" patients-11-13 procedures, that for protanopia B" patients--under 20 procedures. The effects remain at least 1 year after the course.

  1. Spatial attention facilitates assembly of the briefest percepts: Electrophysiological evidence from color fusion.

    PubMed

    Akyürek, Elkan G; van Asselt, E Manon

    2015-12-01

    When two different color stimuli are presented in rapid succession, the resulting percept is sometimes that of a mixture of both colors, due to a perceptual process called color fusion. Although color fusion might seem to occur very early in the visual pathway, and only happens across the briefest of stimulus presentation intervals (< 50 ms), the present study showed that spatial attention can alter the fusion process. In a series of experiments, spatial cues were presented that either validly indicated the location of a pair of (different) color stimuli in successive stimulus arrays, or did not, pointing toward isoluminant gray distractors in the other visual hemifield. Increased color fusion was observed for valid cues across a range of stimulus durations, at the expense of individual color reports. By contrast, perception of repeated, same-color stimulus pairs did not change, suggesting that the enhancement was specific to fusion, not color discrimination per se. Electrophysiological measures furthermore showed that the amplitude of the N1, N2pc, and P3 components of the ERP were differentially modulated during the perception of individual and fused colors, as a function of cueing and stimulus duration. Fusion itself, collapsed across cueing conditions, was reflected uniquely in N1 amplitude. Overall, the results suggest that spatial attention enhances color fusion and decreases competition between stimuli, constituting an adaptive slowdown in service of temporal integration.

  2. Toward a unified color space for perception-based image processing.

    PubMed

    Lissner, Ingmar; Urban, Philipp

    2012-03-01

    Image processing methods that utilize characteristics of the human visual system require color spaces with certain properties to operate effectively. After analyzing different types of perception-based image processing problems, we present a list of properties that a unified color space should have. Due to contradictory perceptual phenomena and geometric issues, a color space cannot incorporate all these properties. We therefore identify the most important properties and focus on creating opponent color spaces without cross contamination between color attributes (i.e., lightness, chroma, and hue) and with maximum perceptual uniformity induced by color-difference formulas. Color lookup tables define simple transformations from an initial color space to the new spaces. We calculate such tables using multigrid optimization considering the Hung and Berns data of constant perceived hue and the CMC, CIE94, and CIEDE2000 color-difference formulas. The resulting color spaces exhibit low cross contamination between color attributes and are only slightly less perceptually uniform than spaces optimized exclusively for perceptual uniformity. We compare the CIEDE2000-based space with commonly used color spaces in two examples of perception-based image processing. In both cases, standard methods show improved results if the new space is used. All color-space transformations and examples are provided as MATLAB codes on our website.

  3. [Improvement of light and color perception in humans upon prolonged administration of eleutherococcus].

    PubMed

    Arushanian, E B; Shikina, I B

    2004-01-01

    The chronic administration of a liquid eleuterococcus extract significantly improves light and color perception in healthy humans. Significant positive changes in eye sensitivity were observed in both morning and evening hours.

  4. Scotopic hue percepts in natural scenes

    PubMed Central

    Elliott, Sarah L.; Cao, Dingcai

    2012-01-01

    Traditional trichromatic theories of color vision conclude that color perception is not possible under scotopic illumination in which only one type of photoreceptor, rods, is active. The current study demonstrates the existence of scotopic color perception and indicates that perceived hue is influenced by spatial context and top-down processes of color perception. Experiment 1 required observers to report the perceived hue in various natural scene images under purely rod-mediated vision. The results showed that when the test patch had low variation in the luminance distribution and was a decrement in luminance compared to the surrounding area, reddish or orangish percepts were more likely to be reported compared to all other percepts. In contrast, when the test patch had a high variation and was an increment in luminance, the probability of perceiving blue, green, or yellow hues increased. In addition, when observers had a strong, but singular, daylight hue association for the test patch, color percepts were reported more often and hues appeared more saturated compared to patches with no daylight hue association. This suggests that experience in daylight conditions modulates the bottom-up processing for rod-mediated color perception. In Experiment 2, observers reported changes in hue percepts for a test ring surrounded by inducing rings that varied in spatial context. In sum, the results challenge the classic view that rod vision is achromatic and suggest that scotopic hue perception is mediated by cortical mechanisms. PMID:24233245

  5. Color character recognition method based on human perception

    NASA Astrophysics Data System (ADS)

    Yamaba, Kazuo; Miyake, Yoichi

    1993-01-01

    Color is one of the most powerful and important types of visual information in various fields such as image processing, electronic imaging, and robot vision technologies. A new color character recognition system, composed of a camera, optical filters, an image board, a neuro board, and a micro computer was constructed. Using typewriter characters and backgrounds in five colors, two kinds of experiments were performed. The first consisted of preliminary experiments testing the effectiveness of the modified opponent-color theory of the human eye for use in machine character recognition. The second was an experiment in color character recognition, in which the system recognized both characters and their colors.

  6. Hazard perception based on safety words and colors: an Indian perspective.

    PubMed

    Borade, Atul B; Bansod, Satish V; Gandhewar, Vivek R

    2008-01-01

    Globalization and trade among developed and developing countries has increased the need of risk communication at the workplace. The purpose of this study was to examine differences in risk communication and perception in various countries. It looked at hazard perception associated with colors and safety words among Indian industry workers. Fifty workers participated in the study focused on hazard rating of 9 safety words and 7 colors. In one part of the study the participants were asked to associate colors with safety words through recalling them from their long-term memory; in another they were asked to associate safety words with given colors. The results showed that certain words and colors implied different hazard rating at the workplace. The rank ordering of safety words and colors varied significantly in different countries. Hence population factors should be taken into consideration when designing standards for hazard communication.

  7. Perception of neon color spreading in 3-6-month-old infants.

    PubMed

    Yang, Jiale; Kanazawa, So; Yamaguchi, Masami K

    2009-12-01

    Although lots of studies about neon color spreading have been reported, few of these studies have focused on the perceptual development of it in human infants. Therefore, this study explores the perceptual development of neon color spreading in infants. In experiment 1, we examined 3-6-month-olds' perception of neon color spreading in static conditions. In experiment 2, we examined 3-6-month-olds' perception of neon color spreading in moving conditions. Our results suggest that while only 5-6-month-old infants show a preference for neon color spreading in the static condition, 3-4-month-old infants also prefer neon color spreading if motion information is available.

  8. The Role of Skin Color on Hispanic Women's Perceptions of Attractiveness

    ERIC Educational Resources Information Center

    Stephens, Dionne P.; Fernandez, Paula

    2012-01-01

    This study relies on qualitative methods to investigate Hispanic women's skin color perceptions. The primary goal is to identify the relevance of these perceptions on their beliefs about their own physical attractiveness. Thirty-four self-identified White-Hispanic women attending a large Hispanic Serving Institution in the southeastern United…

  9. Color vision in attention-deficit/hyperactivity disorder: A pilot visual evoked potential study

    PubMed Central

    Kim, Soyeon; Banaschewski, Tobias; Tannock, Rosemary

    2014-01-01

    Background Individuals with attention-deficit/hyperactivity disorder (ADHD) are reported to manifest visual problems (including ophthalmological and color perception, particularly for blue–yellow stimuli), but findings are inconsistent. Accordingly, this study investigated visual function and color perception in adolescents with ADHD using color Visual Evoked Potentials (cVEP), which provides an objective measure of color perception. Method Thirty-one adolescents (aged 13–18), 16 with a confirmed diagnosis of ADHD, and 15 healthy peers, matched for age, gender, and IQ participated in the study. All underwent an ophthalmological exam, as well as electrophysiological testing color Visual Evoked Potentials (cVEP), which measured the latency and amplitude of the neural P1 response to chromatic (blue–yellow, red–green) and achromatic stimuli. Result No intergroup differences were found in the ophthalmological exam. However, significantly larger P1 amplitude was found for blue and yellow stimuli, but not red/green or achromatic stimuli, in the ADHD group (particularly in the medicated group) compared to controls. Conclusion Larger amplitude in the P1 component for blue–yellow in the ADHD group compared to controls may account for the lack of difference in color perception tasks. We speculate that the larger amplitude for blue–yellow stimuli in early sensory processing (P1) might reflect a compensatory strategy for underlying problems including compromised retinal input of s-cones due to hypo-dopaminergic tone. PMID:25435188

  10. Achromatic doublets using group indices of refraction

    NASA Astrophysics Data System (ADS)

    Rosete-Aguilar, M.; Estrada-Silva, F. C.; Román-Moreno, C. J.; Ortega-Martínez, R.

    2008-03-01

    One main function of short pulses is to concentrate energy in time and space [1]. The use of refractive lenses allows us to concentrate energy in a small volume of focusing around the focal point of the lens. When using refractive lenses, there are three effects that affect the concentration of energy around the focal point of the lens. These are the group velocity dispersion (GVD), the propagation time difference (PTD), and the aberrations of the lens. In this paper, we study lenses which are diffraction limited so that the monochromatic aberrations are negligible; the group velocity dispersion and the propagation time difference are the main effects affecting the spreading of the pulse at the focus. We will show that for 100-fs pulses the spatial spreading is larger than the temporal spreading of the pulse. It is already known that the effect of spatial spreading of the pulse due to PTD can be reduced by using achromatic optics. We use the theory proposed by A. Vaughan to analyze simple lenses and normal achromatic doublets, where normal means doublets that we can buy from catalogs. We then use the Vaughan theory to design achromatic doublets in phase and group, which produce no spatial spreading of the pulse, i.e., PTD = 0, when the doublet is designed for the carrier of the pulse. We compare these phase and group achromatic doublets with normal achromatic doublets. Finally, we show that apochromatic optics can give a much better correction of PTD than using normal achromatic doublets.

  11. Perception of color emotions for single colors in red-green defective observers

    PubMed Central

    Inoue, Takaaki

    2016-01-01

    It is estimated that inherited red-green color deficiency, which involves both the protan and deutan deficiency types, is common in men. For red-green defective observers, some reddish colors appear desaturated and brownish, unlike those seen by normal observers. Despite its prevalence, few studies have investigated the effects that red-green color deficiency has on the psychological properties of colors (color emotions). The current study investigated the influence of red-green color deficiency on the following six color emotions: cleanliness, freshness, hardness, preference, warmth, and weight. Specifically, this study aimed to: (1) reveal differences between normal and red-green defective observers in rating patterns of six color emotions; (2) examine differences in color emotions related to the three cardinal channels in human color vision; and (3) explore relationships between color emotions and color naming behavior. Thirteen men and 10 women with normal vision and 13 men who were red-green defective performed both a color naming task and an emotion rating task with 32 colors from the Berkeley Color Project (BCP). Results revealed noticeable differences in the cleanliness and hardness ratings between the normal vision observers, particularly in women, and red-green defective observers, which appeared mainly for colors in the orange to cyan range, and in the preference and warmth ratings for colors with cyan and purple hues. Similarly, naming errors also mainly occurred in the cyan colors. A regression analysis that included the three cone-contrasts (i.e., red-green, blue-yellow, and luminance) as predictors significantly accounted for variability in color emotion ratings for the red-green defective observers as much as the normal individuals. Expressly, for warmth ratings, the weight of the red-green opponent channel was significantly lower in color defective observers than in normal participants. In addition, the analyses for individual warmth ratings in

  12. Perception of color emotions for single colors in red-green defective observers.

    PubMed

    Sato, Keiko; Inoue, Takaaki

    2016-01-01

    It is estimated that inherited red-green color deficiency, which involves both the protan and deutan deficiency types, is common in men. For red-green defective observers, some reddish colors appear desaturated and brownish, unlike those seen by normal observers. Despite its prevalence, few studies have investigated the effects that red-green color deficiency has on the psychological properties of colors (color emotions). The current study investigated the influence of red-green color deficiency on the following six color emotions: cleanliness, freshness, hardness, preference, warmth, and weight. Specifically, this study aimed to: (1) reveal differences between normal and red-green defective observers in rating patterns of six color emotions; (2) examine differences in color emotions related to the three cardinal channels in human color vision; and (3) explore relationships between color emotions and color naming behavior. Thirteen men and 10 women with normal vision and 13 men who were red-green defective performed both a color naming task and an emotion rating task with 32 colors from the Berkeley Color Project (BCP). Results revealed noticeable differences in the cleanliness and hardness ratings between the normal vision observers, particularly in women, and red-green defective observers, which appeared mainly for colors in the orange to cyan range, and in the preference and warmth ratings for colors with cyan and purple hues. Similarly, naming errors also mainly occurred in the cyan colors. A regression analysis that included the three cone-contrasts (i.e., red-green, blue-yellow, and luminance) as predictors significantly accounted for variability in color emotion ratings for the red-green defective observers as much as the normal individuals. Expressly, for warmth ratings, the weight of the red-green opponent channel was significantly lower in color defective observers than in normal participants. In addition, the analyses for individual warmth ratings in

  13. The Influence of Color on the Perception of Scene Gist

    ERIC Educational Resources Information Center

    Castelhano, Monica S.; Henderson, John M.

    2008-01-01

    In 3 experiments the authors used a new contextual bias paradigm to explore how quickly information is extracted from a scene to activate gist, whether color contributes to this activation, and how color contributes, if it does. Participants were shown a brief presentation of a scene followed by the name of a target object. The target object could…

  14. Mood perception of interior colors in a gym

    NASA Astrophysics Data System (ADS)

    Ohno, Haruyo; Koizumi, Naoko

    2002-06-01

    When people enter a gym, they feel more like exercising in some cases than other cases. The interior color of the space may be a contributing factor. This paper discusses how the interior color of a gym affects female subjects in their twenties and forties to fifties both physiologically and psychologically.

  15. Visual attention to and perception of undamaged and damaged versions of natural and colored female hair.

    PubMed

    Fink, Bernhard; Neuser, Frauke; Deloux, Gwenelle; Röder, Susanne; Matts, Paul J

    2013-03-01

    Female hair color is thought to influence physical attractiveness, and although there is some evidence for this assertion, research has yet not addressed the question if and how physical damaging affects the perception of female hair color. Here we investigate whether people are sensitive (in terms of visual attention and age, health and attractiveness perception) to subtle differences in hair images of natural and colored hair before and after physical damaging. We tracked the eye-gaze of 50 men and 50 women aged 31-50 years whilst they viewed randomized pairs of images of 20 natural and 20 colored hair tresses, each pair displaying the same tress before and after controlled cuticle damage. The hair images were then rated for perceived health, attractiveness, and age. Undamaged versions of natural and colored hair were perceived as significantly younger, healthier, and more attractive than corresponding damaged versions. Visual attention to images of undamaged colored hair was significantly higher compared with their damaged counterparts, while in natural hair, the opposite pattern was found. We argue that the divergence in visual attention to undamaged colored female hair and damaged natural female hair and associated ratings is due to differences in social perception and discuss the source of apparent visual difference between undamaged and damaged hair.

  16. Color-form meanings: interconnections between perception, association and symbolism

    NASA Astrophysics Data System (ADS)

    Newton, Rachel

    2002-06-01

    Every form is as sensitive as a puff of smoke, the slightest breath will alter it completely. Kandinsky-- The interaction between form and color regarding this mutability of meaning is a subject that is ever elusive. At the same time, it remains a subject that merits objective and collective study, not so much to generate finite conclusions but to increase our visual awareness and sensitivity of the complex phenomena at work. Much has been accomplished but it still remains an all but unanswered question. Color effects need to be seen to be believed and, as Albers stated in his Interaction of Color, theory should follow practice. This paper presents recent developments in my painting practice by exploring the combined effects of color phenomena through systematic practical experiment with changing color forms. The work is systematic but embraces the intuitive, the sensual and the magical - closing the gap between intuition and formula. The wide range of meanings (associations, evocations, emotions) that Mark Rothko obtained from subtle changes of form and color in the rectangles- within- rectangles format of his mature paintings, is evidence of the scope of this line of research.

  17. Green love is ugly: emotions elicited by synesthetic grapheme-color perceptions.

    PubMed

    Callejas, Alicia; Acosta, Alberto; Lupiáñez, Juan

    2007-01-05

    Synesthetes who experience grapheme-color synesthesia often report feeling uneasy when dealing with incongruently colored graphemes although no empirical data is available to confirm this phenomenon. We studied this affective reaction related to synesthetic perceptions by means of an evaluation task. We found that the perception of an incorrectly colored word affects the judgments of emotional valence. Furthermore, this effect competed with the word's emotional valence in a categorization task thus supporting the automatic nature of this synesthetically elicited affective reaction. When manipulating word valence and word color-photism congruence, we found that responses were slower (and less accurate) for inconsistent conditions than for consistent conditions. Inconsistent conditions were defined as those where semantics and color-photism congruence did not produce a similar assessment and therefore gave rise to a negative affective reaction (i.e., positive-valence words presented in a color different from the synesthete's photism or negative-valence words presented in the photism's color). We therefore observed a modulation of the congruency effect (i.e., faster reaction times to congruently colored words than incongruently colored words). Although this congruence effect has been taken as an index of the true experience of synesthesia, we observed that it can be reversed when the experimental manipulations turn an incongruently colored word into a consistent stimulus. To our knowledge, this is the first report of an affective reaction elicited by the congruency between the synesthetically induced color of a word and the color in which the word is actually presented. The underlying neural mechanisms that might be involved in this phenomenon are discussed.

  18. Color Perception in Microgravity Conditions: The Results of CROMOS Parabolic Flight Experiment

    NASA Astrophysics Data System (ADS)

    Schlacht, I. L.; Brambillasca, S.; Birke, H.

    2009-01-01

    The aims of this research are first to verify the actual difference in color perception between conditions in Earth's (1× g) and parabolic flight's microgravitational conditions (μg) and to improve the methodology used for data collection, testing the CROMOS software for color sensitivity investigation. Additionally this paper seeks to establish a larger awareness of microgravity vision and its design implications in the field of aerospace engineering. The analysis of variations in color perception between microgravity and 1× g can be applied to a range of fields concerning the space habitat (Fig. 1), the design of information (such as safety notices), or in the space station the analysis of chemical and biological reactions based on chromatography (for example, when subtle color variations are used as indicators in histological cell analysis).

  19. Physiological modeling for detecting degree of perception of a color-deficient person.

    PubMed

    Rajalakshmi, T; Prince, Shanthi

    2017-02-01

    Physiological modeling of retina plays a vital role in the development of high-performance image processing methods to produce better visual perception. People with normal vision have an ability to discern different colors. The situation is different in the case of people with color blindness. The aim of this work is to develop a human visual system model for detecting the level of perception of people with red, green and blue deficiency by considering properties like luminance, spatial and temporal frequencies. Simulation results show that in the photoreceptor, outer plexiform and inner plexiform layers, the energy and intensity level of the red, green and blue component for a normal person is proved to be significantly higher than for dichromats. The proposed method explains with appropriate results that red and blue color blindness people could not perceive red and blue color completely.

  20. Psychophysical evidence for separate channels for the perception of form, color, movement, and depth.

    PubMed

    Livingstone, M S; Hubel, D H

    1987-11-01

    Physiological and anatomical findings in the primate visual system, as well as clinical evidence in humans, suggest that different components of visual information processing are segregated into largely independent parallel pathways. Such a segregation leads to certain predictions about human vision. In this paper we describe psychophysical experiments on the interactions of color, form, depth, and movement in human perception, and we attempt to correlate these aspects of visual perception with the different subdivisions of the visual system.

  1. Smooth pursuit eye movements improve temporal resolution for color perception.

    PubMed

    Terao, Masahiko; Watanabe, Junji; Yagi, Akihiro; Nishida, Shin'ya

    2010-06-21

    Human observers see a single mixed color (yellow) when different colors (red and green) rapidly alternate. Accumulating evidence suggests that the critical temporal frequency beyond which chromatic fusion occurs does not simply reflect the temporal limit of peripheral encoding. However, it remains poorly understood how the central processing controls the fusion frequency. Here we show that the fusion frequency can be elevated by extra-retinal signals during smooth pursuit. This eye movement can keep the image of a moving target in the fovea, but it also introduces a backward retinal sweep of the stationary background pattern. We found that the fusion frequency was higher when retinal color changes were generated by pursuit-induced background motions than when the same retinal color changes were generated by object motions during eye fixation. This temporal improvement cannot be ascribed to a general increase in contrast gain of specific neural mechanisms during pursuit, since the improvement was not observed with a pattern flickering without changing position on the retina or with a pattern moving in the direction opposite to the background motion during pursuit. Our findings indicate that chromatic fusion is controlled by a cortical mechanism that suppresses motion blur. A plausible mechanism is that eye-movement signals change spatiotemporal trajectories along which color signals are integrated so as to reduce chromatic integration at the same locations (i.e., along stationary trajectories) on the retina that normally causes retinal blur during fixation.

  2. "Shades of beauty": examining the relationship of skin color to perceptions of physical attractiveness.

    PubMed

    Frisby, Cynthia M

    2006-08-01

    The purpose of this research project was to investigate the relationship between skin color and level of perceived physical attractiveness. Previous research suggested that skin color plays an important role in how we perceive an individual's physical attractiveness. The current study was conducted to determine how influential the role of race is on perceptions of physical attractiveness. In this study, 79 subjects were asked to evaluate images of potential endorsers to be used in an upcoming advertising campaign. The images were those of females of varying skin tones. Data were then collected and analyzed to determine whether skin tone and level of skin color can in fact influence the physical attractiveness stereotype.

  3. LED light with enhanced color saturation and improved white light perception.

    PubMed

    Feng, Xiangfen; Xu, Wei; Han, Qiuyi; Zhang, Shanduan

    2016-01-11

    The light emitting diodes (LEDs) with high light quality were investigated to enhance the color appearance of the illuminated objects and increase the white light perception of the ambience. The spectral power distributions of the LED lights were optimized by addition of the RGB components and by shifting the color coordinate below the blackbody line to get desired color rendering index (CRI) and high gamut area index (GAI). The results of the human factor study reveal that the "perfect" white light can be achieved to both enhance color saturation and improve light visual impression. The effects of observer metamerism were studied to clarify the observed phenomenon that the white lights with the same color coordinates were perceived differently by real observers.

  4. See no evil: color blindness and perceptions of subtle racial discrimination in the workplace.

    PubMed

    Offermann, Lynn R; Basford, Tessa E; Graebner, Raluca; Jaffer, Salman; De Graaf, Sumona Basu; Kaminsky, Samuel E

    2014-10-01

    Workplace discrimination has grown more ambiguous, with interracial interactions often perceived differently by different people. The present study adds to the literature by examining a key individual difference variable in the perception of discrimination at work, namely individual color-blind attitudes. We examined relationships between 3 dimensions of color-blind attitudes (Racial Privilege, Institutional Discrimination, and Blatant Racial Issues) and perceptions of racial microaggressions in the workplace as enacted by a White supervisor toward a Black employee (i.e., discriminatory actions ranging from subtle to overt). Findings showed that observer views on institutional discrimination fully mediated, and blatant racial issues partially mediated, the relationships between racial group membership and the perception of workplace microaggressions. Non-Hispanic Whites endorsed color blindness as institutional discrimination and blatant racial issues significantly more than members of racioethnic minority groups, and higher levels of color-blind worldviews were associated with lower likelihoods of perceiving microaggressions. Views on racial privilege did not differ significantly between members of different racial groups or affect microaggression perceptions. Implications for organizations concerned about promoting more inclusive workplaces are discussed.

  5. Striking individual differences in color perception uncovered by 'the dress' photograph.

    PubMed

    Lafer-Sousa, Rosa; Hermann, Katherine L; Conway, Bevil R

    2015-06-29

    'The dress' is a peculiar photograph: by themselves the dress' pixels are brown and blue, colors associated with natural illuminants, but popular accounts (#TheDress) suggest the dress appears either white/gold or blue/black. Could the purported categorical perception arise because the original social-media question was an alternative-forced-choice? In a free-response survey (N = 1401), we found that most people, including those naïve to the image, reported white/gold or blue/black, but some said blue/brown. Reports of white/gold over blue/black were higher among older people and women. On re-test, some subjects reported a switch in perception, showing the image can be multistable. In a language-independent measure of perception, we asked subjects to identify the dress' colors from a complete color gamut. The results showed three peaks corresponding to the main descriptive categories, providing additional evidence that the brain resolves the image into one of three stable percepts. We hypothesize that these reflect different internal priors: some people favor a cool illuminant (blue sky), discount shorter wavelengths, and perceive white/gold; others favor a warm illuminant (incandescent light), discount longer wavelengths, and see blue/black. The remaining subjects may assume a neutral illuminant, and see blue/brown. We show that by introducing overt cues to the illumination, we can flip the dress color.

  6. Neurobiological hypothesis of color appearance and hue perception

    PubMed Central

    Schmidt, Brian P.; Neitz, Maureen; Neitz, Jay

    2014-01-01

    DeValois and DeValois (1993) showed that to explain hue appearance, S-cone signals have to be combined with M vs. L opponent signals in two different ways to produce red-green and yellow-blue axes respectively. Recently, it has been shown that color appearance is normal for individuals with genetic mutations that block S-cone input to blue-on ganglion cells. This is inconsistent with the DeValois hypothesis in which S-opponent konio-geniculate signals are combined with L−M signals at a 3rd processing stage in cortex. Instead, here we show that color appearance, including individual differences never explained before, are predicted by a model in which S-cone signals are combined with L vs. M signals in the outer retina. PMID:24695170

  7. Categorical Perception Beyond the Basic Level: The Case of Warm and Cool Colors.

    PubMed

    Holmes, Kevin J; Regier, Terry

    2016-07-12

    Categories can affect our perception of the world, rendering between-category differences more salient than within-category ones. Across many studies, such categorical perception (CP) has been observed for the basic-level categories of one's native language. Other research points to categorical distinctions beyond the basic level, but it does not demonstrate CP for such distinctions. Here we provide such a demonstration. Specifically, we show CP in English speakers for the non-basic distinction between "warm" and "cool" colors, claimed to represent the earliest stage of color lexicon evolution. Notably, the advantage for discriminating colors that straddle the warm-cool boundary was restricted to the right visual field-the same behavioral signature previously observed for basic-level categories. This pattern held in a replication experiment with increased power. Our findings show that categorical distinctions beyond the basic-level repertoire of one's native language are psychologically salient and may be spontaneously accessed during normal perceptual processing.

  8. Object knowledge changes visual appearance: semantic effects on color afterimages.

    PubMed

    Lupyan, Gary

    2015-10-01

    According to predictive coding models of perception, what we see is determined jointly by the current input and the priors established by previous experience, expectations, and other contextual factors. The same input can thus be perceived differently depending on the priors that are brought to bear during viewing. Here, I show that expected (diagnostic) colors are perceived more vividly than arbitrary or unexpected colors, particularly when color input is unreliable. Participants were tested on a version of the 'Spanish Castle Illusion' in which viewing a hue-inverted image renders a subsequently shown achromatic version of the image in vivid color. Adapting to objects with intrinsic colors (e.g., a pumpkin) led to stronger afterimages than adapting to arbitrarily colored objects (e.g., a pumpkin-colored car). Considerably stronger afterimages were also produced by scenes containing intrinsically colored elements (grass, sky) compared to scenes with arbitrarily colored objects (books). The differences between images with diagnostic and arbitrary colors disappeared when the association between the image and color priors was weakened by, e.g., presenting the image upside-down, consistent with the prediction that color appearance is being modulated by color knowledge. Visual inputs that conflict with prior knowledge appear to be phenomenologically discounted, but this discounting is moderated by input certainty, as shown by the final study which uses conventional images rather than afterimages. As input certainty is increased, unexpected colors can become easier to detect than expected ones, a result consistent with predictive-coding models.

  9. Cortical response to categorical color perception in infants investigated by near-infrared spectroscopy

    PubMed Central

    Yang, Jiale; Kanazawa, So; Yamaguchi, Masami K.; Kuriki, Ichiro

    2016-01-01

    Perceptual color space is continuous; however, we tend to divide it into only a small number of categories. It is unclear whether categorical color perception is obtained solely through the development of the visual system or whether it is affected by language acquisition. To address this issue, we recruited prelinguistic infants (5- to 7-mo-olds) to measure changes in brain activity in relation to categorical color differences by using near-infrared spectroscopy (NIRS). We presented two sets of geometric figures to infants: One set altered in color between green and blue, and the other set altered between two different shades of green. We found a significant increase in hemodynamic responses during the between-category alternations, but not during the within-category alternations. These differences in hemodynamic response based on categorical relationship were observed only in the bilateral occipitotemporal regions, and not in the occipital region. We confirmed that categorical color differences yield behavioral differences in infants. We also observed comparable hemodynamic responses to categorical color differences in adults. The present study provided the first evidence, to our knowledge, that colors of different categories are represented differently in the visual cortex of prelinguistic infants, which implies that color categories may develop independently before language acquisition. PMID:26858441

  10. Threshold value for the perception of color changes of human gingiva.

    PubMed

    Sailer, Irena; Fehmer, Vincent; Ioannidis, Alexis; Hämmerle, Christoph H F; Thoma, Daniel S

    2014-01-01

    The aim of this study was to assess the threshold value for the perception of color changes of human gingiva. Standardized presentations of five cases in the esthetic zone were made with the gingiva and teeth separated. The color parameters L, a, and b (CIELab) of the gingival layers were adjusted to induce darker and lighter colors. In the presentations, the right side (maxillary right anterior) was unchanged, while the left side (maxillary left anterior) of the pictures was modified. Ten dentists, 10 dental technicians, and 10 lay people evaluated the color difference of the pictures. The mean ΔE threshold values ranged between 1.6 ± 1.1 (dental technicians) and 3.4 ± 1.9 (lay people). The overall ΔE amounted to 3.1 ± 1.5.

  11. Perceptions of racial confrontation: the role of color blindness and comment ambiguity.

    PubMed

    Zou, Linda X; Dickter, Cheryl L

    2013-01-01

    Because of its emphasis on diminishing race and avoiding racial discourse, color-blind racial ideology has been suggested to have negative consequences for modern day race relations. The current research examined the influence of color blindness and the ambiguity of a prejudiced remark on perceptions of a racial minority group member who confronts the remark. One hundred thirteen White participants responded to a vignette depicting a White character making a prejudiced comment of variable ambiguity, after which a Black target character confronted the comment. Results demonstrated that the target confronter was perceived more negatively and as responding less appropriately by participants high in color blindness, and that this effect was particularly pronounced when participants responded to the ambiguous comment. Implications for the ways in which color blindness, as an accepted norm that is endorsed across legal and educational settings, can facilitate Whites' complicity in racial inequality are discussed.

  12. Perception of the color red enhances the force and velocity of motor output.

    PubMed

    Elliot, Andrew J; Aarts, Henk

    2011-04-01

    The present research examined whether perception of the color red influences basic motor functioning. Prior research on color and motor functioning has been guided by ill-defined theoretical statements, and has been plagued by methodological problems. Drawing on theoretical and empirical work on the threat-behavior link in human and nonhuman animals, we proposed and tested the prediction that perceiving red enhances the force and velocity of motor output. Experiment 1 demonstrated that red, relative to gray (matched to red on lightness), facilitates pinchgrip force. Experiment 2 demonstrated that red, relative to gray (matched to red on lightness) and blue (matched to red on lightness and chroma) facilitates handgrip force and the velocity of that force. These findings clearly establish a link between red and basic motor action, illustrate the importance of rigorous experimental methods when testing color effects, and highlight the need to attend to the functional, as well as aesthetic, value of color.

  13. The male blue crab, Callinectes sapidus, uses both chromatic and achromatic cues during mate choice.

    PubMed

    Baldwin, Jamie; Johnsen, Sönke

    2012-04-01

    In the blue crab, Callinectes sapidus, claw color varies by sex, sexual maturity and individual. Males rely in part on color cues to select appropriate mates, and these chromatic cues may be perceived through an opponent interaction between two photoreceptors with maximum wavelength sensitivities at 440 and 508 nm. The range of color discrimination of this dichromatic visual system may be limited, however, and it is unclear whether male blue crabs are capable of discriminating the natural variations in claw color that may be important in mate choice. By testing males' innate color preferences in binary choice tests between photographs of red-clawed females and six variations of orange-clawed females, we examined both the chromatic (opponent interaction) and achromatic (relative luminance) cues used in male mate choice. Males significantly preferred red-clawed females to orange-clawed females, except when the test colors were similar in both opponency and relative luminance. Our results are unusual in that they indicate that male mate choice in the blue crab is not guided solely by achromatic or chromatic mechanisms, suggesting that both color and intensity are used to evaluate female claw color.

  14. Correlations between color perception and motor function impairment in children with spastic cerebral palsy

    PubMed Central

    2014-01-01

    Introduction The aim of the present study was to evaluate color perception thresholds and relate them to the degree of motor impairment in children with spastic cerebral palsy (SCP). Methods Binocular and monocular chromaticity discrimination thresholds were estimated for the protan, deutan, and tritan color confusion axes in 43 SCP children aged 6–15 years who were classified as tetraplegic (n = 12), diplegic (n = 16), and hemiplegic (n = 15) without ophthalmological complaints. Motor impairment was rated according to the Gross Motor Function Classification System (GMFCS) in five levels of severity. Results Analysis of variance showed significantly reduced discrimination in tetraplegic children (p < 0.001) compared with the diplegic, hemiplegic, and control groups. We also found a positive correlation between chromaticity discrimination thresholds and GMFCS ratings in all of the groups. Discussion Chromaticity discrimination thresholds measured psychophysically were reduced for all three color confusion axis in tetraplegic children compared with normal children. Diplegic and hemiplegic children had similar results as normal children. The finding of a correlation between quantified motor impairment and color discrimination losses in SCP patients is a new observation that might help elucidate the causes of color perception loss in these patients. Visual information is essential for the rehabilitation of CP children. Knowledge of the degree of correlation between vision and motor impairment is valuable when planning a rehabilitation program. PMID:24961924

  15. Gamut relativity: a new computational approach to brightness and lightness perception.

    PubMed

    Vladusich, Tony

    2013-01-09

    This article deconstructs the conventional theory that "brightness" and "lightness" constitute perceptual dimensions corresponding to the physical dimensions of luminance and reflectance, and builds in its place the theory that brightness and lightness correspond to computationally defined "modes," rather than dimensions, of perception. According to the theory, called gamut relativity, "blackness" and "whiteness" constitute the perceptual dimensions (forming a two-dimensional "blackness-whiteness" space) underlying achromatic color perception (black, white, and gray shades). These perceptual dimensions are postulated to be related to the neural activity levels in the ON and OFF channels of vision. The theory unifies and generalizes a number of extant concepts in the brightness and lightness literature, such as simultaneous contrast, anchoring, and scission, and quantitatively simulates several challenging perceptual phenomena, including the staircase Gelb effect and the effects of task instructions on achromatic color-matching behavior, all with a single free parameter. The theory also provides a new conception of achromatic color constancy in terms of the relative distances between points in blackness-whiteness space. The theory suggests a host of striking conclusions, the most important of which is that the perceptual dimensions of vision should be generically specified according to the computational properties of the brain, rather than in terms of "reified" physical dimensions. This new approach replaces the computational goal of estimating absolute physical quantities ("inverse optics") with the goal of computing object properties relatively.

  16. The orientation selectivity of color-responsive neurons in macaque V1.

    PubMed

    Johnson, Elizabeth N; Hawken, Michael J; Shapley, Robert

    2008-08-06

    Form has a strong influence on color perception. We investigated the neural basis of the form-color link in macaque primary visual cortex (V1) by studying orientation selectivity of single V1 cells for pure color patterns. Neurons that responded to color were classified, based on cone inputs and spatial selectivity, into chromatically single-opponent and double-opponent groups. Single-opponent cells responded well to color but weakly to luminance contrast; they were not orientation selective for color patterns. Most double-opponent cells were orientation selective to pure color stimuli as well as to achromatic patterns. We also found non-opponent cells that responded weakly or not at all to pure color; most were orientation selective for luminance patterns. Double-opponent and non-opponent cells' orientation selectivities were not contrast invariant; selectivity usually increased with contrast. Double-opponent cells were approximately equally orientation selective for luminance and equiluminant color stimuli when stimuli were matched in average cone contrast. V1 double-opponent cells could be the neural basis of the influence of form on color perception. The combined activities of single- and double-opponent cells in V1 are needed for the full repertoire of color perception.

  17. Segregation of form, color, movement, and depth: anatomy, physiology, and perception.

    PubMed

    Livingstone, M; Hubel, D

    1988-05-06

    Anatomical and physiological observations in monkeys indicate that the primate visual system consists of several separate and independent subdivisions that analyze different aspects of the same retinal image: cells in cortical visual areas 1 and 2 and higher visual areas are segregated into three interdigitating subdivisions that differ in their selectivity for color, stereopsis, movement, and orientation. The pathways selective for form and color seem to be derived mainly from the parvocellular geniculate subdivisions, the depth- and movement-selective components from the magnocellular. At lower levels, in the retina and in the geniculate, cells in these two subdivisions differ in their color selectivity, contrast sensitivity, temporal properties, and spatial resolution. These major differences in the properties of cells at lower levels in each of the subdivisions led to the prediction that different visual functions, such as color, depth, movement, and form perception, should exhibit corresponding differences. Human perceptual experiments are remarkably consistent with these predictions. Moreover, perceptual experiments can be designed to ask which subdivisions of the system are responsible for particular visual abilities, such as figure/ground discrimination or perception of depth from perspective or relative movement--functions that might be difficult to deduce from single-cell response properties.

  18. Segregation of Form, Color, Movement, and Depth: Anatomy, Physiology, and Perception

    NASA Astrophysics Data System (ADS)

    Livingstone, Margaret; Hubel, David

    1988-05-01

    Anatomical and physiological observations in monkeys indicate that the primate visual system consists of several separate and independent subdivisions that analyze different aspects of the same retinal image: cells in cortical visual areas 1 and 2 and higher visual areas are segregated into three interdigitating subdivisions that differ in their selectivity for color, stereopsis, movement, and orientation. The pathways selective for form and color seem to be derived mainly from the parvocellular geniculate subdivisions, the depth- and movement-selective components from the magnocellular. At lower levels, in the retina and in the geniculate, cells in these two subdivisions differ in their color selectivity, contrast sensitivity, temporal properties, and spatial resolution. These major differences in the properties of cells at lower levels in each of the subdivisions led to the prediction that different visual functions, such as color, depth, movement, and form perception, should exhibit corresponding differences. Human perceptual experiments are remarkably consistent with these predictions. Moreover, perceptual experiments can be designed to ask which subdivisions of the system are responsible for particular visual abilities, such as figure/ground discrimination or perception of depth from perspective or relative movement--functions that might be difficult to deduce from single-cell response properties.

  19. Color segmentation in the HSI color space using the K-means algorithm

    NASA Astrophysics Data System (ADS)

    Weeks, Arthur R.; Hague, G. Eric

    1997-04-01

    Segmentation of images is an important aspect of image recognition. While grayscale image segmentation has become quite a mature field, much less work has been done with regard to color image segmentation. Until recently, this was predominantly due to the lack of available computing power and color display hardware that is required to manipulate true color images (24-bit). TOday, it is not uncommon to find a standard desktop computer system with a true-color 24-bit display, at least 8 million bytes of memory, and 2 gigabytes of hard disk storage. Segmentation of color images is not as simple as segmenting each of the three RGB color components separately. The difficulty of using the RGB color space is that it doesn't closely model the psychological understanding of color. A better color model, which closely follows that of human visual perception is the hue, saturation, intensity model. This color model separates the color components in terms of chromatic and achromatic information. Strickland et al. was able to show the importance of color in the extraction of edge features form an image. His method enhances the edges that are detectable in the luminance image with information from the saturation image. Segmentation of both the saturation and intensity components is easily accomplished with any gray scale segmentation algorithm, since these spaces are linear. The modulus 2(pi) nature of the hue color component makes its segmentation difficult. For example, a hue of 0 and 2(pi) yields the same color tint. Instead of applying separate image segmentation to each of the hue, saturation, and intensity components, a better method is to segment the chromatic component separately from the intensity component because of the importance that the chromatic information plays in the segmentation of color images. This paper presents a method of using the gray scale K-means algorithm to segment 24-bit color images. Additionally, this paper will show the importance the hue

  20. A conflict-based model of color categorical perception: evidence from a priming study.

    PubMed

    Hu, Zhonghua; Hanley, J Richard; Zhang, Ruiling; Liu, Qiang; Roberson, Debi

    2014-10-01

    Categorical perception (CP) of color manifests as faster or more accurate discrimination of two shades of color that straddle a category boundary (e.g., one blue and one green) than of two shades from within the same category (e.g., two different shades of green), even when the differences between the pairs of colors are equated according to some objective metric. The results of two experiments provide new evidence for a conflict-based account of this effect, in which CP is caused by competition between visual and verbal/categorical codes on within-category trials. According to this view, conflict arises because the verbal code indicates that the two colors are the same, whereas the visual code indicates that they are different. In Experiment 1, two shades from the same color category were discriminated significantly faster when the previous trial also comprised a pair of within-category colors than when the previous trial comprised a pair from two different color categories. Under the former circumstances, the CP effect disappeared. According to the conflict-based model, response conflict between visual and categorical codes during discrimination of within-category pairs produced an adjustment of cognitive control that reduced the weight given to the categorical code relative to the visual code on the subsequent trial. Consequently, responses on within-category trials were facilitated, and CP effects were reduced. The effectiveness of this conflict-based account was evaluated in comparison with an alternative view that CP reflects temporary warping of perceptual space at the boundaries between color categories.

  1. What Can We Learn from Toddlers about Categorical Perception of Color? Comments on Goldstein, Davidoff, and Roberson

    ERIC Educational Resources Information Center

    Franklin, Anna; Wright, Oliver; Davies, Ian R. L.

    2009-01-01

    We comment on Goldstein, Davidoff, and Roberson's replication and extension ("Journal of Experimental Child Psychology, 102", 219-238 [2009]) of our study of the effect of toddlers' color term knowledge on their categorical perception (CP) of color ("Journal of Experimental Child Psychology, 90", 114-141 [2005]). First, we discuss how best to…

  2. Grapheme-color synesthesia interferes with color perception in a standard Stroop task.

    PubMed

    van der Veen, F M; Aben, H P; Smits, M; Röder, C H

    2014-01-31

    This study examined the proposed automatic and involuntary nature of synesthetic experiences in grapheme-color synesthetes by comparing behavioral and blood-oxygen level dependent (BOLD) responses in a synesthetic and a standard version of the Stroop task. Clear interference effects in terms of slower reaction times and stronger BOLD responses in the rostral cingulate zone (RCZ) were found in synesthetes performing the synesthetic version of the Stroop task. Surprisingly, less interference was found in synesthetes compared with controls performing the standard Stroop task. This smaller interference effect, expressed as the difference in reaction time between incongruent and neutral stimuli, was explained in terms of experienced interference during the neutral condition of the Stroop task in synesthetes. This was confirmed by stronger BOLD responses in the RCZ for synesthetes specifically in the neutral condition. To the best of our knowledge, this is the first study to show different performance of synesthetes in a standard Stroop task and the presented data can be seen as strong evidence for the automatic and involuntary nature of synesthetic experiences.

  3. Color perception is impaired in baseball batters while performing an interceptive action.

    PubMed

    Sasada, Manami; Nakamoto, Hiroki; Ikudome, Sachi; Unenaka, Satoshi; Mori, Shiro

    2015-08-01

    In order to test the theoretical idea that experts rely more on the dorsal stream than the ventral stream during interceptive action for the interception of a moving target, the present study investigates the perception of color (dominant in ventral processing) during interceptive action in fast-ball sports. Twelve college baseball players and 12 non-baseball players performed a coincident-timing task with target color changes (from white to red, blue, or white) at various time points (at 100, 200, or 300 ms before target arrival). In this task, participants swung a bat and/or pressed a button in response to the target's arrival at a prespecified location. Participants were then asked to state the final color of the target. Baseball players, but not non-baseball players, were significantly less proficient at identifying color changes during the bat-swing condition relative to the button-press condition, irrespective of the time points of color change. These results are consistent with the idea that baseball players rely more on the dorsal stream during bat swinging for the interception of a moving target than do novices.

  4. Back to the USSR: How Colors Might Shape the Political Perception of East versus West

    PubMed Central

    Gebauer, Fabian; Raab, Marius H.

    2016-01-01

    People typically process information to confirm their prior held attitudes and stereotypes. As the political relations between NATO and Russia have distinctively drifted apart in recent years, we were interested in how far old-established color depictions referring to the Cold War’s demarcations (USSR = red; NATO = blue) might reinforce people’s political perception of an East versus West antagonism nowadays. Participants received a fabricated news article in which both world powers were either depicted on a map as Russia = red and NATO = blue or vice versa (Study 1). Testing a different sample in Study 2, we fully removed color assignments and used hachured distinctions or no distinctions at all. We revealed that perceived political distance between both sides increased particularly for participants with negative attitudes toward Russia, but only when Russia was depicted in red. Thus, colors referring to the old-established Cold War patterns can indeed shape the political perception and reinforce stereotypical East versus West thinking. PMID:27895886

  5. Back to the USSR: How Colors Might Shape the Political Perception of East versus West.

    PubMed

    Gebauer, Fabian; Raab, Marius H; Carbon, Claus-Christian

    2016-01-01

    People typically process information to confirm their prior held attitudes and stereotypes. As the political relations between NATO and Russia have distinctively drifted apart in recent years, we were interested in how far old-established color depictions referring to the Cold War's demarcations (USSR = red; NATO = blue) might reinforce people's political perception of an East versus West antagonism nowadays. Participants received a fabricated news article in which both world powers were either depicted on a map as Russia = red and NATO = blue or vice versa (Study 1). Testing a different sample in Study 2, we fully removed color assignments and used hachured distinctions or no distinctions at all. We revealed that perceived political distance between both sides increased particularly for participants with negative attitudes toward Russia, but only when Russia was depicted in red. Thus, colors referring to the old-established Cold War patterns can indeed shape the political perception and reinforce stereotypical East versus West thinking.

  6. A color fusion method of infrared and low-light-level images based on visual perception

    NASA Astrophysics Data System (ADS)

    Han, Jing; Yan, Minmin; Zhang, Yi; Bai, Lianfa

    2014-11-01

    The color fusion images can be obtained through the fusion of infrared and low-light-level images, which will contain both the information of the two. The fusion images can help observers to understand the multichannel images comprehensively. However, simple fusion may lose the target information due to inconspicuous targets in long-distance infrared and low-light-level images; and if targets extraction is adopted blindly, the perception of the scene information will be affected seriously. To solve this problem, a new fusion method based on visual perception is proposed in this paper. The extraction of the visual targets ("what" information) and parallel processing mechanism are applied in traditional color fusion methods. The infrared and low-light-level color fusion images are achieved based on efficient typical targets learning. Experimental results show the effectiveness of the proposed method. The fusion images achieved by our algorithm can not only improve the detection rate of targets, but also get rich natural information of the scenes.

  7. Integrated Optics Achromatic Nuller for Stellar Interferometry

    NASA Technical Reports Server (NTRS)

    Ksendzov, Alexander

    2012-01-01

    This innovation will replace a beam combiner, a phase shifter, and a mode conditioner, thus simplifying the system design and alignment, and saving weight and space in future missions. This nuller is a dielectric-waveguide-based, four-port asymmetric coupler. Its nulling performance is based on the mode-sorting property of adiabatic asymmetric couplers that are intrinsically achromatic. This nuller has been designed, and its performance modeled, in the 6.5-micrometer to 9.25-micrometer spectral interval (36% bandwidth). The calculated suppression of starlight for this 15-cm-long device is 10(exp -5) or better through the whole bandwidth. This is enough to satisfy requirements of a flagship exoplanet-characterization mission. Nulling interferometry is an approach to starlight suppression that will allow the detection and spectral characterization of Earth-like exoplanets. Nulling interferometers separate the light originating from a dim planet from the bright starlight by placing the star at the bottom of a deep, destructive interference fringe, where the starlight is effectively cancelled, or nulled, thus allowing the faint off-axis light to be much more easily seen. This process is referred to as nulling of the starlight. Achromatic nulling technology is a critical component that provides the starlight suppression in interferometer-based observatories. Previously considered space-based interferometers are aimed at approximately 6-to-20-micrometer spectral range. While containing the spectral features of many gases that are considered to be signatures of life, it also offers better planet-to-star brightness ratio than shorter wavelengths. In the Integrated Optics Achromatic Nuller (IOAN) device, the two beams from the interferometer's collecting telescopes pass through the same focusing optic and are incident on the input of the nuller.

  8. Achromatic beam transport of High Current Injector

    NASA Astrophysics Data System (ADS)

    Kumar, Sarvesh; Mandal, A.

    2016-02-01

    The high current injector (HCI) provides intense ion beams of high charge state using a high temperature superconducting ECR ion source. The ion beam is accelerated upto a final energy of 1.8 MeV/u due to an electrostatic potential, a radio frequency quadrupole (RFQ) and a drift tube linac (DTL). The ion beam has to be transported to superconducting LINAC which is around 50 m away from DTL. This section is termed as high energy beam transport section (HEBT) and is used to match the beam both in transverse and longitudinal phase space to the entrance of LINAC. The HEBT section is made up of four 90 deg. achromatic bends and interconnecting magnetic quadrupole triplets. Two RF bunchers have been used for longitudinal phase matching to the LINAC. The ion optical design of HEBT section has been simulated using different beam dynamics codes like TRACEWIN, GICOSY and TRACE 3D. The field computation code OPERA 3D has been utilized for hardware design of all the magnets. All the dipole and quadrupole magnets have been field mapped and their test results such as edge angles measurements, homogeneity and harmonic analysis etc. are reported. The whole design of HEBT section has been performed such that the most of the beam optical components share same hardware design and there is ample space for beam diagnostics as per geometry of the building. Many combination of achromatic bends have been simulated to transport the beam in HEBT section but finally the four 90 deg. achromatic bend configuration is found to be the best satisfying all the geometrical constraints with simplified beam tuning process in real time.

  9. An achromatic low-order wavefront sensor

    NASA Astrophysics Data System (ADS)

    Brousseau, Denis; Allain, Guillaume; Thibault, Simon; Véran, Jean-Pierre

    2016-07-01

    Many wavefront sensors have been developed over the years, but most are not well suited for the photon-limited regime of coronagraphs designed for 10-9 contrast ratios and small inner working angles (IWAs). To meet current coronagraphs low-order wavefront sensing requirements, it is essential to have a method that offers high sensitivity and preferably a linear response. We propose an innovative low-order wavefront sensor (LOWFS) design that is both achromatic and near free of non-common path aberrations (NCPAs).

  10. An analytical study of double bend achromat lattice

    SciTech Connect

    Fakhri, Ali Akbar Kant, Pradeep; Singh, Gurnam; Ghodke, A. D.

    2015-03-15

    In a double bend achromat, Chasman-Green (CG) lattice represents the basic structure for low emittance synchrotron radiation sources. In the basic structure of CG lattice single focussing quadrupole (QF) magnet is used to form an achromat. In this paper, this CG lattice is discussed and an analytical relation is presented, showing the limitation of basic CG lattice to provide the theoretical minimum beam emittance in achromatic condition. To satisfy theoretical minimum beam emittance parameters, achromat having two, three, and four quadrupole structures is presented. In this structure, different arrangements of QF and defocusing quadruple (QD) are used. An analytical approach assuming quadrupoles as thin lenses has been followed for studying these structures. A study of Indus-2 lattice in which QF-QD-QF configuration in the achromat part has been adopted is also presented.

  11. Assessment of perceptibility and acceptability of color variations between matched teeth among trainee dentist and lay person

    PubMed Central

    Ramesh, A. S.; Sharma, Aruna; Rijesh, K.; Prakash, R.; Devi, Lakshmi; Raja, Edilbert

    2015-01-01

    Aim: The aim of this study was to find the difference in perceptibility and acceptability of changes done to various color coordinates of matched teeth, between trainee dental surgeons, and lay person. Materials and Methods: A photograph with a set of matched central incisor teeth was selected. In one of the central incisors, the color coordinates (hue, value, and chroma) were altered to a preset value. These pictures were presented to trainee dental surgeons and lay person and their level of perception of color change and acceptance of color change was registered and compared. Results: It was found that trainee dental surgeons fared better in perceiving the color change and accepted less of the color changed specimens. The dimension of color that was more discerned both by lay person and trainee dental surgeons was value, hue, and last chroma. Conclusion: When compared to a lay person, dental surgeons are more acute in perceiving color changes and do not accept the color difference between teeth to a higher degree. PMID:26538933

  12. Passive, achromatic, nearly isochronous bending system

    DOEpatents

    Douglas, David R.; Yunn, Byung C.

    2004-05-18

    A particle beam bending system having a geometry that applies active bending only beyond the chord of the orbit for any momentum component. Using this bending configuration, all momentum components emerge dispersed in position only; all trajectories are parallel by construction. Combining a pair of such bends with reflective symmetry produces a bend cell that is, by construction, achromatic to all orders. By the particular choice of 45.degree. individual bends, a pair of such achromats can be used as the basis of a 180.degree. recirculation arc. Other rational fractions of a full 180.degree. bend serve equally well (e.g., 2 bends/cell.times.90.degree./bend.times.1 cell /arc; 2 bends/cell.times.30.degree./bend.times.3 cells/arc, etc), as do combinations of multiple bending numerologies (e.g., 2 bends/cell.times.22.5.degree./bend.times.2 cells+2 bends/cell.times.45.degree./bend.times.1 cell). By the choice of entry pole face rotation of the first magnet and exit pole face rotation of the second magnet (with a value to be determined from the particular beam stability requirements imposed by the choice of bending angle and beam properties to be used in any particular application), desirable focusing properties can be introduced and beam stability can be insured.

  13. Differences in Brain Hemodynamics in Response to Achromatic and Chromatic Cards of the Rorschach

    PubMed Central

    2016-01-01

    Abstract. In order to investigate the effects of color stimuli of the Rorschach inkblot method (RIM), the cerebral activity of 40 participants with no history of neurological or psychiatric illness was scanned while they engaged in the Rorschach task. A scanned image of the ten RIM inkblots was projected onto a screen in the MRI scanner. Cerebral activation in response to five achromatic color cards and five chromatic cards were compared. As a result, a significant increase in brain activity was observed in bilateral visual areas V2 and V3, parietooccipital junctions, pulvinars, right superior temporal gyrus, and left premotor cortex for achromatic color cards (p < .001). For the cards with chromatic color, significant increase in brain activity was observed in left visual area V4 and left orbitofrontal cortex (p < .001). Furthermore, a conjoint analysis revealed various regions were activated in responding to the RIM. The neuropsychological underpinnings of the response process, as described by Acklin and Wu-Holt (1996), were largely confirmed. PMID:28239255

  14. Orientation tuning of binocular summation: a comparison of colour to achromatic contrast

    PubMed Central

    Gheiratmand, Mina; Cherniawsky, Avital S.; Mullen, Kathy T.

    2016-01-01

    A key function of the primary visual cortex is to combine the input from the two eyes into a unified binocular percept. At low, near threshold, contrasts a process of summation occurs if the visual inputs from the two eyes are similar. Here we measure the orientation tuning of binocular summation for chromatic and equivalent achromatic contrast. We derive estimates of orientation tuning by measuring binocular summation as a function of the orientation difference between two sinusoidal gratings presented dichoptically to different eyes. We then use a model to estimate the orientation bandwidth of the neural detectors underlying the binocular combination. We find that orientation bandwidths are similar for chromatic and achromatic stimuli at both low (0.375 c/deg) and mid (1.5 c/deg) spatial frequencies, with an overall average of 29 ± 3 degs (HWHH, s.e.m). This effect occurs despite the overall greater binocular summation found for the low spatial frequency chromatic stimuli. These results suggest that similar, oriented processes underlie both chromatic and achromatic binocular contrast combination. The non-oriented detection process found in colour vision at low spatial frequencies under monocular viewing is not evident at the binocular combination stage. PMID:27168119

  15. Aggression, academic behaviors, and popularity perceptions among boys of color during the transition to middle school.

    PubMed

    Xie, Hongling; Dawes, Molly; Wurster, Tabitha J; Shi, Bing

    2013-01-01

    The transition to middle school often presents behavioral and academic challenges to youths. Boys of color (i.e., African American and Hispanic in this study) may be especially vulnerable. In this study, peer nominations of aggressive and academic behaviors as well as youths' perceptions of how these behaviors were related to popularity in peer networks were obtained from the spring semester of fifth grade through the spring semester of seventh grade, with the transition occurring as the students entered the sixth grade. The sample included 188 boys (71 Caucasian, 90 African American, and 27 Hispanic) from an urban school district in the northeastern United States. Trajectory analyses showed that African American boys scored lower in studentship and higher in rule-breaking and aggressive (both physical and social) behaviors prior to the transition, and such differences among ethnic groups were largely maintained during the transition. Hispanic boys displayed decreases in their studentship during the transition. African American boys' perception of how studentship affects popularity was more positive than other boys prior to the transition, but it decreased during the transition. African American boys also endorsed rule breaking and physical and social aggression more positively for popularity prior to the transition, whereas Caucasian and Hispanic boys' endorsement increased during the transition and eventually caught up with those of African American boys in seventh grade. A positive within-individual association was found between youths' popularity perception and their behavior for studentship, rule breaking, and physical aggression, which did not differ by ethnicity.

  16. ACHRO: A program to help design achromatic bends

    SciTech Connect

    Rusthoi, D.

    1993-01-01

    ACHRO is a very simple 2000-line. FORTRAN code that provides help for the designer of the achromatic bend. Given a beam momentum, the program calculates the required drift lengths and dipole parameters which it will apply to any one of several different types of achromats. The types of achromats that the code helps to design include the Enge dual-270,'' the Brown 2-dipole, the Leboutet 3-dipole, and the Enge 4-dipole, as well as the periodic systems which can be designed to any order in symmetric, nonsymmetric and stair-step varieties. Given the dimensions into which a bend must fit, ACHRO will calculate the geometrical parameters in an X-Y plane for a single or multiple achromat, and for achromatic S-bend'' configurations where possible. ACHRO makes it very easy to optimize a bend with respect to drift lengths and magnet parameters by allowing the user to change parameter values and see the resulting calculation. Used in conjunction with a beam-transport code, ACHRO makes it possible for a designer to consider various types of achromatic bends in the same beamline layout in order to compare important bend characteristics such as dispersion, Isochronicity, sensitivity, geometric and chromatic aberrations, aperture requirements, space for diagnostics, etc., all of which are largely a function of the geometry and the type of achromat selected.

  17. Exogenous attention and color perception: performance and appearance of saturation and hue.

    PubMed

    Fuller, Stuart; Carrasco, Marisa

    2006-11-01

    Exogenous covert attention is an automatic, transient form of attention that can be triggered by sudden changes in the periphery. Here we test for the effects of attention on color perception. We used the methodology developed by Carrasco, Ling, and Read [Carrasco, M., Ling, S., & Read, S. (2004). Attention alters appearance. Nature Neuroscience, 7 (3) 308-313] to explore the effects of exogenous attention on appearance of saturation (Experiment 1) and of hue (Experiment 2). We also tested orientation discrimination performance for single stimuli defined by saturation or hue (Experiment 3). The results indicate that attention increases apparent saturation, but does not change apparent hue, notwithstanding the fact that it improves orientation discrimination for both saturation and hue stimuli.

  18. Retention of Faculty of Color in Rehabilitation Counselor Education as It Relates to Their Perception of the Academic Climate

    ERIC Educational Resources Information Center

    Minor, Tameika D.

    2016-01-01

    This study investigates the relationships between demographic characteristics, perceptions of the academic climate, and the employment continuation plans of tenured and tenure-track faculty of color in CORE accredited rehabilitation counselor education (RCE) programs. Furthermore, this study aims to identify which factors best predict the…

  19. Central serous chorioretinopathy resulting in altered vision and color perception after glenohumeral corticosteroid injection.

    PubMed

    Hurvitz, Andrew P; Hodapp, Kristin L; Jadgchew, Jason; Solomon, Daniel J; Stolldorf, Hunter S; Provencher, Matthew T

    2009-08-01

    Complications from shoulder corticosteroid injections are uncommon. This article presents a case of altered color perception and visual disturbances in a 29-year-old male active duty Navy SEAL following an intra-articular glenohumeral corticosteroid injection, previously unreported in the orthopedic literature. The corticosteroid injection was administered for the treatment of right-shoulder stiffness occurring approximately 3 months following an arthroscopic superior labrum anterior-posterior (SLAP) repair and subacromial decompression of the ipsilateral shoulder. The patient experienced immediate relief after the injection. Seven days later, however, he began to notice visual disturbances with color and image distortion of his right eye. He also developed a papular, nonpruritic rash on his upper trunk that eventually extended down his legs. He was diagnosed by an ophthalmologist as having central serous chorioretinopathy, a condition in which serous fluid accumulates in the subretinal space of the eye, causing detachment of the retina from the underlying retinal pigment epithelium. The reaction spontaneously resolved within approximately 10 to 12 weeks without treatment. Although intra-articular corticosteroid injections are frequently performed with a low rate of complication, clinicians should be familiar with this rare yet distressing condition. Furthermore, patients with increased production of endogenous corticosteroids (eg, those with Cushing's syndrome, type A personality, hypertension, or obstructive sleep apnea) should be warned of the potential of chorioretinopathy after an intra-articular corticosteroid injection.

  20. Gradient Index Polymer Optics: Achromatic Singlet Lens Design

    DTIC Science & Technology

    2010-01-01

    achromatic singlet lenses. The designs are based on gradient index lenses fabricated from nanolayered polymer materials. Raytraced results confirm the...fabricated from nanolayered polymer materials. Raytraced results confirm the achromatic performance of the designs. OCIS codes: (110.2760) Gradient...lenses in Zemax®. In order to model these lenses, user-defined surfaces had to be developed for the software. RL RG z y • • Δz • tc •n0 n1• Raytrace

  1. Real-time multiple human perception with color-depth cameras on a mobile robot.

    PubMed

    Zhang, Hao; Reardon, Christopher; Parker, Lynne E

    2013-10-01

    The ability to perceive humans is an essential requirement for safe and efficient human-robot interaction. In real-world applications, the need for a robot to interact in real time with multiple humans in a dynamic, 3-D environment presents a significant challenge. The recent availability of commercial color-depth cameras allow for the creation of a system that makes use of the depth dimension, thus enabling a robot to observe its environment and perceive in the 3-D space. Here we present a system for 3-D multiple human perception in real time from a moving robot equipped with a color-depth camera and a consumer-grade computer. Our approach reduces computation time to achieve real-time performance through a unique combination of new ideas and established techniques. We remove the ground and ceiling planes from the 3-D point cloud input to separate candidate point clusters. We introduce the novel information concept, depth of interest, which we use to identify candidates for detection, and that avoids the computationally expensive scanning-window methods of other approaches. We utilize a cascade of detectors to distinguish humans from objects, in which we make intelligent reuse of intermediary features in successive detectors to improve computation. Because of the high computational cost of some methods, we represent our candidate tracking algorithm with a decision directed acyclic graph, which allows us to use the most computationally intense techniques only where necessary. We detail the successful implementation of our novel approach on a mobile robot and examine its performance in scenarios with real-world challenges, including occlusion, robot motion, nonupright humans, humans leaving and reentering the field of view (i.e., the reidentification challenge), human-object and human-human interaction. We conclude with the observation that the incorporation of the depth information, together with the use of modern techniques in new ways, we are able to create an

  2. Achromatic phase shifting focal plane masks

    NASA Astrophysics Data System (ADS)

    Newman, Kevin

    The search for life on other worlds is an exciting scientific endeavor that could change the way we perceive our place in the universe. Thousands of extrasolar planets have been discovered using indirect detection techniques. One of the most promising methods for discovering new exoplanets and searching for life is direct imaging with a coronagraph. Exoplanet coronagraphy of Earth-like planets is a challenging task, but we have developed many of the tools necessary to make it feasible. The Phase-Induced Amplitude Apodization (PIAA) Coronagraph is one of the highest-performing architectures for direct exoplanet imaging. With a complex phase-shifting focal plane mask, the PIAA Complex Mask Coronagraph (PIAACMC) can approach the theoretical performance limit for any direct detection technique. The architecture design is flexible enough to be applied to any arbitrary aperture shape, including segmented and obscured apertures. This is an important feature for compatibility with next-generation ground and space-based telescopes. PIAA and PIAACMC focal plane masks have been demonstrated in monochromatic light. An important next step for high-performance coronagraphy is the development of broadband phase-shifting focal plane masks. In this dissertation, we present an algorithm for designing the PIAA and PIAACMC focal plane masks to operate in broadband. We also demonstrate manufacturing of the focal plane masks, and show laboratory results. We use simulations to show the potential performance of the coronagraph system, and the use of wavefront control to correct for mask manufacturing errors. Given the laboratory results and simulations, we show new areas of exoplanet science that can potentially be explored using coronagraph technology. The main conclusion of this dissertation is that we now have the tools required to design and manufacture PIAA and PIAACMC achromatic focal plane masks. These tools can be applied to current and future telescope systems to enable new

  3. One-stage model for color conversion.

    NASA Technical Reports Server (NTRS)

    Richards, W.

    1972-01-01

    Description of a one-stage approximation to the color-conversion model of Richards and Parks (1971). The modified model proposes three channels for color vision, each with different center-surround sensitivities. In its strongest form, the model predicts that the gain-setting control that alters the sensitivities of each channel is solely a function of achromatic contrast.

  4. The perception of three-dimensional contours and the effect of luminance polarity and color change on their detection.

    PubMed

    Khuu, Sieu K; Honson, Vanessa; Kim, Juno

    2016-01-01

    In the present study we investigated the detectability of three-dimensional (3D) cocircular contours defined by binocular disparity and established the influence of a number of stimulus factors to their perception. In Experiment 1 we examined the depth range over which local elements are grouped in depth, and whether contour detectability systematically changed with the degree to which they are oriented in depth. We found that increasing the orientation of curved contours in depth improved detection performance. In Experiment 2, we examined the degree to which contour detection was disrupted by varying their continuity in depth by jittering the local depth position of contour elements. Detection performance declined with the increasing displacement of local contour elements in depth away from the depth orientation of the contour. Experiments 3 and 4 ascertained whether a detection advantage is afforded to 3D contours defined by local variations in luminance polarity and color. Local color and polarity differences can disrupt the two-dimensional grouping of local contour elements on the basis of similarity, but we tested whether continuity in depth facilitates grouping of contour elements differing in polarity and color. We found no detection advantage for 3D contours defined by local color and polarity variations, suggesting binocular disparity does not facilitate grouping in depth when local elements differ in color and polarity. These findings further suggest the visual system uses binocular disparity to detect contours, but is likely to involve systems tuned to luminance polarity and color.

  5. What can we learn from toddlers about categorical perception of color? Comments on Goldstein, Davidoff, and Roberson.

    PubMed

    Franklin, Anna; Wright, Oliver; Davies, Ian R L

    2009-02-01

    We comment on Goldstein, Davidoff, and Roberson's replication and extension (Journal of Experimental Child Psychology, 102, 219-238 [2009]) of our study of the effect of toddlers' color term knowledge on their categorical perception (CP) of color (Journal of Experimental Child Psychology, 90, 114-141 [2005]). First, we discuss how best to assess color term knowledge when concerned with the effects of language on color CP. A reanalysis of our data indicates that even toddlers who do not know the terms for the relevant focal colors still show CP. Second, we comment on Goldstein and colleagues' finding of blue-purple CP, as we did, but not of blue-green CP in Himba toddlers. We present contrasting data from Wright (unpublished PhD thesis, University of Surrey, 2006) that demonstrates blue-green CP in Himba toddlers. Finally, we discuss the limitations of the approach taken by all of these investigations and discuss theoretical accounts of the origin and nature of color CP.

  6. OPTIMIZING THE DYNAMIC APERTURE FOR TRIPLE BEND ACHROMATIC LATTICES.

    SciTech Connect

    KRAMER, S.L.; BENGTSSON, J.

    2006-06-26

    The Triple Bend Achromatic (TBA) lattice has the potential for lower natural emittance per period than the Double Bend Achromatic (DBA) lattice for high brightness light sources. However, the DBA has been chosen for 3rd generation light sources more often due to the higher number of undulator straight section available for a comparable emittance. The TBA has considerable flexibility in linear optics tuning while maintaining this emittance advantage. We have used the tune and chromaticity flexibility of a TBA lattice to minimize the lowest order nonlinearities to implement a 3rd order achromatic tune, while maintaining a constant emittance. This frees the geometric sextupoles to counter the higher order nonlinearities. This procedure is being used to improve the nonlinear dynamics of the TBA as a proposed lattice for NSLS-II facility. The flexibility of the TBA lattice will also provide for future upgrade capabilities of the beam parameters.

  7. Evolution of the circuitry for conscious color vision in primates.

    PubMed

    Neitz, J; Neitz, M

    2017-02-01

    There are many ganglion cell types and subtypes in our retina that carry color information. These have appeared at different times over the history of the evolution of the vertebrate visual system. They project to several different places in the brain and serve a variety of purposes allowing wavelength information to contribute to diverse visual functions. These include circadian photoentrainment, regulation of sleep and mood, guidance of orienting movements, detection and segmentation of objects. Predecessors to some of the circuits serving these purposes presumably arose before mammals evolved and different functions are represented by distinct ganglion cell types. However, while other animals use color information to elicit motor movements and regulate activity rhythms, as do humans, using phylogenetically ancient circuitry, the ability to appreciate color appearance may have been refined in ancestors to primates, mediated by a special set of ganglion cells that serve only that purpose. Understanding the circuitry for color vision has implications for the possibility of treating color blindness using gene therapy by recapitulating evolution. In addition, understanding how color is encoded, including how chromatic and achromatic percepts are separated is a step toward developing a complete picture of the diversity of ganglion cell types and their functions. Such knowledge could be useful in developing therapeutic strategies for blinding eye disorders that rely on stimulating elements in the retina, where more than 50 different neuron types are organized into circuits that transform signals from photoreceptors into specialized detectors many of which are not directly involved in conscious vision.

  8. Skin Color and Self-Perceptions of Immigrant and U.S.-Born Latinas: The Moderating Role of Racial Socialization and Ethnic Identity

    ERIC Educational Resources Information Center

    Telzer, Eva H.; Vazquez Garcia, Heidie A.

    2009-01-01

    Research has increasingly identified race as a salient characteristic that affects one's life experiences and psychological well-being. However, little is known about how skin color affects the emotional health of Latinos. The present study examined how skin color relates to the self-perceptions of immigrant (N = 26) and U.S.-born (N = 55) Latina…

  9. Electrophysiological Markers of Categorical Perception of Color in 7-Month Old Infants

    ERIC Educational Resources Information Center

    Clifford, Alexandra; Franklin, Anna; Davies, Ian R. L.; Holmes, Amanda

    2009-01-01

    The origin of color categories has been debated by psychologists, linguists and cognitive scientists for many decades. Here, we present the first electrophysiological evidence for categorical responding to color before color terms are acquired. Event-related potentials were recorded on a visual oddball task in 7-month old infants. Infants were…

  10. Effects of Black and White, Authentic and Contrived Color on Children's Perceptions of Dynamic Picture Content.

    ERIC Educational Resources Information Center

    Vollan, Clayton J.

    A study was devised to determine whether, if color is found superior to black-and-white for communicating dynamic picture content, that superiority can be attributed to the realism of authentic color, or whether that superiority is the effect of the simple presence of color. A sample of 90 sixth grade students were shown slides, half of which…

  11. An Investigation of the Eighteenth-Century Achromatic Telescope

    ERIC Educational Resources Information Center

    Jaecks, Duane H.

    2010-01-01

    The optical quality and properties of over 200 telescopes residing in museums and private collections have been measured and tested with the goal of obtaining new information about the early development of the achromatic lens (1757-1770). Quantitative measurements of the chromatic and spherical aberration of telescope objective lenses were made…

  12. Grounding context in face processing: color, emotion, and gender.

    PubMed

    Gil, Sandrine; Le Bigot, Ludovic

    2015-01-01

    In recent years, researchers have become interested in the way that the affective quality of contextual information transfers to a perceived target. We therefore examined the effect of a red (vs. green, mixed red/green, and achromatic) background - known to be valenced - on the processing of stimuli that play a key role in human interactions, namely facial expressions. We also examined whether the valenced-color effect can be modulated by gender, which is also known to be valenced. Female and male adult participants performed a categorization task of facial expressions of emotion in which the faces of female and male posers expressing two ambiguous emotions (i.e., neutral and surprise) were presented against the four different colored backgrounds. Additionally, this task was completed by collecting subjective ratings for each colored background in the form of five semantic differential scales corresponding to both discrete and dimensional perspectives of emotion. We found that the red background resulted in more negative face perception than the green background, whether the poser was female or male. However, whereas this valenced-color effect was the only effect for female posers, for male posers, the effect was modulated by both the nature of the ambiguous emotion and the decoder's gender. Overall, our findings offer evidence that color and gender have a common valence-based dimension.

  13. Experimental and theoretical studies of perceptible color fading of decorative paints consisting of mixed pigments

    NASA Astrophysics Data System (ADS)

    Auger, Jean-Claude; McLoughlin, Daragh

    2017-01-01

    We study the color fading of paints films composed of mixtures of white rutile titanium dioxide and yellow arylide pigments dispersed in two polymer binders at different volume concentrations. The samples were exposed to ultraviolet radiations in an accelerated weathering tester during three weeks. The measured patterns in color variations appeared to be independent of the chemistry of the binders. We then developed a theoretical framework, based on the Radiative transfer Equation of light and the One Particle T-Matrix formalism to simulate the color fading process. The loss of color is correlated to the progressive decrease of the original colored pigment volume-filling fraction as the destructive UV radiations penetrate deeper into the films. The calculated patterns of color variations of paints film composed by mixtures of white pigments with yellow Cadmium Sulfate (CdS) and red Cerium Sulfide (Ce2S3) pigments showed the same trend as that seen experimentally.

  14. Sharing Our Unheard Voices: Perceptions of the Lived Experience of Teachers of Color

    ERIC Educational Resources Information Center

    Berrios, Darline

    2016-01-01

    In public education, approximately 80% of teachers in the United States are White, yet close to half of the student population are students of color (U.S. Department of Education, 2011). Gaps in teacher diversity compared with students of color are found in every state across the country (Center for American Progress, 2011). In 2004, the National…

  15. Improving information perception from digital images for users with dichromatic color vision

    NASA Astrophysics Data System (ADS)

    Shayeghpour, Omid; Nyström, Daniel; Gooran, Sasan

    2014-01-01

    Color vision deficiency (CVD) is the inability, or limited ability, to recognize colors and discriminate between them. A person with this condition perceives a narrower range of colors compared to a person with normal color vision. In this study we concentrate on recoloring digital images in such a way that users with CVD, especially dichromats, perceive more details from the recolored images compared to the original ones. During this color transformation process, the goal is to keep the overall contrast of the image constant, while adjusting the colors that might cause confusion for the CVD user. In this method, RGB values at each pixel of the image are first converted into HSV values and, based on pre-defined rules, the problematic colors are adjusted into colors that are perceived better by the user. Comparing the simulation of the original image, as it would be perceived by a dichromat, with the same dichromatic simulation on the recolored image, clearly shows that our method can eliminate a lot of confusion for the user and convey more details. Moreover, an online questionnaire was created and a group of 39 CVD users confirmed that the transformed images allow them to perceive more information compared to the original images.

  16. Effects of aging on figure-ground perception: Convexity context effects and competition resolution.

    PubMed

    Lass, Jordan W; Bennett, Patrick J; Peterson, Mary A; Sekuler, Allison B

    2017-02-01

    We examined age-related differences in figure-ground perception by exploring the effect of age on Convexity Context Effects (CCE; Peterson & Salvagio, 2008). Experiment 1, using Peterson and Salvagio's procedure and black and white stimuli consisting of 2 to 8 alternating concave and convex regions, established that older adults exhibited reduced CCEs compared to younger adults. Experiments 2 and 3 demonstrated that this age difference was found at various stimulus durations and sizes. Experiment 4 compared CCEs obtained with achromatic stimuli, in which the alternating convex and concave regions were each all black or all white, and chromatic stimuli in which the concave regions were homogeneous in color but the convex regions varied in color. We found that the difference between CCEs measured with achromatic and colored stimuli was larger in older than in younger adults. Our results are consistent with the hypothesis that the senescent visual system is less able to resolve the competition among various perceptual interpretations of the figure-ground relations among stimulus regions.

  17. Color and Visual Factors in ATC Displays

    DTIC Science & Technology

    2006-06-01

    displayed materials (called distractors ) within the surrounding visual field that typically spans a view angle of 20~40 degrees. Because achromatic at...create conspicuous differ- ences between a target and distractors . Thus, pop-out of color-coded information in complex scenes is extremely efficient and...We summarized the important results as follows: 1) Color can effectively draw attention when a colored target is brighter than distractors , and the

  18. An fMRI version of the Farnsworth-Munsell 100-Hue test reveals multiple color-selective areas in human ventral occipitotemporal cortex.

    PubMed

    Beauchamp, M S; Haxby, J V; Jennings, J E; DeYoe, E A

    1999-01-01

    Studies of patients with cerebral achromatopsia have suggested that ventral occipitotemporal cortex is important for color perception. We created a functional magnetic resonance imaging (fMRI) version of a clinical test commonly used to assess achromatopsia, the Farnsworth-Munsell 100-Hue test. The test required normal subjects to use color information in the visual stimulus to perform a color sequencing task. A modification of the test requiring ordering by luminance was used as a control task. Subjects were also imaged as they passively viewed colored stimuli. A limited number of areas responded more to chromatic than achromatic stimulation, including primary visual cortex. Most color-selective activity was concentrated in ventral occipitotemporal cortex. Several areas in ventral cortex were identified. The most posterior, located in posterior fusiform gyrus, corresponded to the area activated by passive viewing of colored stimuli. More anterior and medial color-selective areas were located in the collateral sulcus and fusiform gyrus. These more anterior areas were not identified in previous imaging studies which used passive viewing of colored stimuli, and were most active in our study when visual color information was behaviorally relevant, suggesting that attention influences activity in color-selective areas. The fMRI version of the Farnsworth-Munsell test may be useful in the study of achromatopsia.

  19. Achromatic correction of diffractive dispersion in white light SLM imaging.

    PubMed

    Bouchal, Zdeněk; Chlup, Vladimír; Celechovský, Radek; Bouchal, Petr; Nistor, Ioan Cristian

    2014-05-19

    In contemporary optics, the spatial light modulator (SLM) is effectively used as a flexible optoelectronic device playing the key role in a number of experiments of science and technology. Its operation is optimal when using almost monochromatic light but an extremely strong diffractive dispersion occurs when white light is applied. In this paper, the design concepts are proposed resulting in optimization and implementation of a refractive corrector cooperating with the SLM. The corrector maintains the operation of the SLM unchanged for the central wavelength of light and ensures an achromatic dispersion compensation throughout the visible region in applications based on a lens-pattern formation. A significant improvement of the imaging performance of the achromatic SLM was proved by the computer simulation and measurement of the chromatic focal shift and the image contrast of the resolution target.

  20. A simple analytical method to obtain achromatic waveplate retarders

    NASA Astrophysics Data System (ADS)

    Vilas, Jose Luis; Lazarova-Lazarova, Aleksandra

    2017-04-01

    A new linear and analytical method to design achromatic retarders using waveplates is proposed. The root of this procedure is a generalization of the Hariharan method, which supposes a set of waveplates with fast axes aligned. Hence, it imposes a set of contour conditions over the overall retardation with the aim of determining the thicknesses of the waveplates. Our method proposes a polynomial approximation of the birefringences, thus removing the contour condition. Analytic expressions for calculating the thicknesses of the waveplates are then derived, showing a non-explicit dependence on the wavelength. Moreover, the overall retardation obtained by this method is close to the optimal retardation curve achieved by minimizing the merit function of the achromatism degree.

  1. Relationship between Color and Emotion: A Study of College Students

    ERIC Educational Resources Information Center

    Kaya, Naz; Epps, Helen H.

    2004-01-01

    Ninety-eight college students were asked to indicate their emotional responses to five principle hues (i.e., red, yellow, green, blue, purple), five intermediate hues (i.e., yellow-red, green-yellow, blue-green, purple-blue, and red-purple), and three achromatic colors (white, gray, and black) and the reasons for their choices. The color stimuli…

  2. The influence of chromatic context on binocular color rivalry: Perception and neural representation

    PubMed Central

    Hong, Sang Wook; Shevell, Steven K.

    2008-01-01

    The predominance of rivalrous targets is affected by surrounding context when stimuli rival in orientation, motion or color. This study investigated the influence of chromatic context on binocular color rivalry. The predominance of rivalrous chromatic targets was measured in various surrounding contexts. The first experiment showed that a chromatic surround's influence was stronger when the surround was uniform or a grating with luminance contrast (chromatic/black grating) compared to an equiluminant grating (chromatic/white). The second experiment revealed virtually no effect of the orientation of the surrounding chromatic context, using chromatically rivalrous vertical gratings. These results are consistent with a chromatic representation of the context by a non-oriented, chromatically selective and spatially antagonistic receptive field. Neither a double-opponent receptive field nor a receptive field without spatial antagonism accounts for the influence of context on binocular color rivalry. PMID:18331750

  3. Color polymorphism in a land snail Cepaea nemoralis (Pulmonata: Helicidae) as viewed by potential avian predators

    NASA Astrophysics Data System (ADS)

    Surmacki, Adrian; Ożarowska-Nowicka, Agata; Rosin, Zuzanna M.

    2013-06-01

    Avian predation is one of the most probable factors maintaining polymorphism of shell coloration in Cepaea nemoralis. This assumption is justified by the fact that birds frequently forage on snails and their prey choice varies with morph coloration. However, in all preceding studies, the conspicuousness of morphs was determined only by using human vision which is significantly different from birds' visual perception. In this study, we assessed how birds perceive colors of four Cepaea nemoralis morphs using physiological models of avian color vision. We calculated combined chromatic and achromatic contrast between shells and three habitat background types as a measure of shell conspicuousness. The degree of background color matching in Cepaea nemoralis depended on both shell morph and habitat type. On average, banded morphs were more conspicuous than unbanded morphs. Morphs were the most cryptic against dry vegetation and the most conspicuous on bare ground. We also found a significant interaction between habitat type and color morph. The relative conspicuousness of shell morphs depended on habitat and was the most variable against green vegetation. Our study provides the first insight into how potential avian predators view Cepaea nemoralis morphs. The results are discussed in light of multiple hypotheses explaining selective predation on Cepaea nemoralis morphs.

  4. A Spectrophotometric Study of Plumage Color in the Eared Dove (Zenaida auriculata), the Most Abundant South American Columbiforme

    PubMed Central

    Benitez-Vieyra, Santiago Miguel

    2016-01-01

    For birds, plumage color perception is critical in social interactions such as courtship, in both monochromatic and dichromatic species. In the Eared Dove (Zenaida auriculata), perhaps the most abundant South American Columbiforme, the plumage of males and females looks alike and both sexes share the same melanistic coloration with gray and pink tones. The aim of this study was therefore to determine whether evident sexual dichromatism exists in the plumage of the Eared Dove using a spectrophotometry technique in the avian-visible range (300–700 nm). The results of the classic colorimetric variables analysis (hue, chroma and brightness) show that males are in general brighter and have higher UV chroma values than females. The avian visual model points to differences in achromatic and chromatic levels between males and females in body regions possibly involved in sexual selection (e.g. the crown). The model also indicates chromatic or achromatic differences in body regions not subject to sexual selection such as the black spots on the wing coverts and white tail bands, both of which may be involved in intra- or inter-gender-specific communication. PMID:27213273

  5. A Spectrophotometric Study of Plumage Color in the Eared Dove (Zenaida auriculata), the Most Abundant South American Columbiforme.

    PubMed

    Valdez, Diego Javier; Benitez-Vieyra, Santiago Miguel

    2016-01-01

    For birds, plumage color perception is critical in social interactions such as courtship, in both monochromatic and dichromatic species. In the Eared Dove (Zenaida auriculata), perhaps the most abundant South American Columbiforme, the plumage of males and females looks alike and both sexes share the same melanistic coloration with gray and pink tones. The aim of this study was therefore to determine whether evident sexual dichromatism exists in the plumage of the Eared Dove using a spectrophotometry technique in the avian-visible range (300-700 nm). The results of the classic colorimetric variables analysis (hue, chroma and brightness) show that males are in general brighter and have higher UV chroma values than females. The avian visual model points to differences in achromatic and chromatic levels between males and females in body regions possibly involved in sexual selection (e.g. the crown). The model also indicates chromatic or achromatic differences in body regions not subject to sexual selection such as the black spots on the wing coverts and white tail bands, both of which may be involved in intra- or inter-gender-specific communication.

  6. The physiology and psychophysics of the color-form relationship: a review

    PubMed Central

    Moutoussis, Konstantinos

    2015-01-01

    The relationship between color and form has been a long standing issue in visual science. A picture of functional segregation and topographic clustering emerges from anatomical and electrophysiological studies in animals, as well as by brain imaging studies in human. However, one of the many roles of chromatic information is to support form perception, and in some cases it can do so in a way superior to achromatic (luminance) information. This occurs both at an early, contour-detection stage, as well as in late, higher stages involving spatial integration and the perception of global shapes. Pure chromatic contrast can also support several visual illusions related to form-perception. On the other hand, form seems a necessary prerequisite for the computation and assignment of color across space, and there are several respects in which the color of an object can be influenced by its form. Evidently, color and form are mutually dependent. Electrophysiological studies have revealed neurons in the visual brain able to signal contours determined by pure chromatic contrast, the spatial tuning of which is similar to that of neurons carrying luminance information. It seems that, especially at an early stage, form is processed by several, independent systems that interact with each other, each one having different tuning characteristics in color space. At later processing stages, mechanisms able to combine information coming from different sources emerge. A clear interaction between color and form is manifested by the fact that color-form contingencies can be observed in various perceptual phenomena such as adaptation aftereffects and illusions. Such an interaction suggests a possible early binding between these two attributes, something that has been verified by both electrophysiological and fMRI studies. PMID:26578989

  7. Differing Perceptions: How Students of Color and White Students Perceive Campus Climate for Underrepresented Groups

    ERIC Educational Resources Information Center

    Rankin, Susan R.; Reason, Robert D.

    2005-01-01

    Using a campus climate assessment instrument developed by Rankin (1998), we surveyed students (n = 7,347) from 10 campuses to explore whether students from different racial groups experienced their campus climates differently. Students of color experienced harassment at higher rates than Caucasian students, although female White students reported…

  8. A Study into the Perceptions of Students of Color and Their Ninth-Grade Academic Experience

    ERIC Educational Resources Information Center

    Barnes, J. Ako; Eadens, Daniel

    2014-01-01

    Barnes, Mullen, and Lieb (2013) suggested that the effective implementation of the freshman academy promoted positive achievement outcomes for students of color. From a sociocultural perspective through the theoretical framework of Critical Race Theory (CRT), understanding the existence of racism is crucial to a positive academic environment…

  9. Bimodel Perception of Color and Temperature in Six-Month-Old Infants.

    ERIC Educational Resources Information Center

    Rolfe, Sharne A.; Lloyd-Smith, Janice I.

    Two experiments were conducted to explore infant responsiveness to color and temperature novelty under bimodal conditions. In experiment 1, a total of 48 infants of 26-31 weeks were familiarized with a warm-red, warm-blue, cool-red, or cool-blue object, and assigned to one of three experimental groups. Each group was stimulated by a novel test…

  10. Components of Attention in Grapheme-Color Synesthesia: A Modeling Approach.

    PubMed

    Ásgeirsson, Árni Gunnar; Nordfang, Maria; Sørensen, Thomas Alrik

    2015-01-01

    Grapheme-color synesthesia is a condition where the perception of graphemes consistently and automatically evokes an experience of non-physical color. Many have studied how synesthesia affects the processing of achromatic graphemes, but less is known about the synesthetic processing of physically colored graphemes. Here, we investigated how the visual processing of colored letters is affected by the congruence or incongruence of synesthetic grapheme-color associations. We briefly presented graphemes (10-150 ms) to 9 grapheme-color synesthetes and to 9 control observers. Their task was to report as many letters (targets) as possible, while ignoring digit (distractors). Graphemes were either congruently or incongruently colored with the synesthetes' reported grapheme-color association. A mathematical model, based on Bundesen's (1990) Theory of Visual Attention (TVA), was fitted to each observer's data, allowing us to estimate discrete components of visual attention. The models suggested that the synesthetes processed congruent letters faster than incongruent ones, and that they were able to retain more congruent letters in visual short-term memory, while the control group's model parameters were not significantly affected by congruence. The increase in processing speed, when synesthetes process congruent letters, suggests that synesthesia affects the processing of letters at a perceptual level. To account for the benefit in processing speed, we propose that synesthetic associations become integrated into the categories of graphemes, and that letter colors are considered as evidence for making certain perceptual categorizations in the visual system. We also propose that enhanced visual short-term memory capacity for congruently colored graphemes can be explained by the synesthetes' expertise regarding their specific grapheme-color associations.

  11. Components of Attention in Grapheme-Color Synesthesia: A Modeling Approach

    PubMed Central

    Ásgeirsson, Árni Gunnar; Nordfang, Maria; Sørensen, Thomas Alrik

    2015-01-01

    Grapheme-color synesthesia is a condition where the perception of graphemes consistently and automatically evokes an experience of non-physical color. Many have studied how synesthesia affects the processing of achromatic graphemes, but less is known about the synesthetic processing of physically colored graphemes. Here, we investigated how the visual processing of colored letters is affected by the congruence or incongruence of synesthetic grapheme-color associations. We briefly presented graphemes (10–150 ms) to 9 grapheme-color synesthetes and to 9 control observers. Their task was to report as many letters (targets) as possible, while ignoring digit (distractors). Graphemes were either congruently or incongruently colored with the synesthetes’ reported grapheme-color association. A mathematical model, based on Bundesen’s (1990) Theory of Visual Attention (TVA), was fitted to each observer’s data, allowing us to estimate discrete components of visual attention. The models suggested that the synesthetes processed congruent letters faster than incongruent ones, and that they were able to retain more congruent letters in visual short-term memory, while the control group’s model parameters were not significantly affected by congruence. The increase in processing speed, when synesthetes process congruent letters, suggests that synesthesia affects the processing of letters at a perceptual level. To account for the benefit in processing speed, we propose that synesthetic associations become integrated into the categories of graphemes, and that letter colors are considered as evidence for making certain perceptual categorizations in the visual system. We also propose that enhanced visual short-term memory capacity for congruently colored graphemes can be explained by the synesthetes’ expertise regarding their specific grapheme-color associations. PMID:26252019

  12. Achromatic phase matching at third orders of dispersion

    DOEpatents

    Richman, Bruce

    2003-10-21

    Achromatic phase-matching (APM) is used for efficiently multiplying the frequency of broad bandwidth light by using a nonlinear optical medium comprising a second-harmonic generation (SHG) crystal and stationary optical elements whose configuration, properties, and arrangement have been optimized to match the angular dispersion characteristics of the SHG crystal to at least the third order. These elements include prisms and diffraction gratings for directing an input light beam onto the SHG crystal such that each ray wavelength is aligned to match the phase-matching angle for the crystal at each wavelength of light to at least the third order and such that every ray wavelength overlap within the crystal.

  13. Ultra-broadband achromatic imaging with diffractive photon sieves

    NASA Astrophysics Data System (ADS)

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-06-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element.

  14. Large-deviation achromatic Risley prisms pointing systems

    NASA Astrophysics Data System (ADS)

    Lacoursiere, Jean; Doucet, Michel; Curatu, Eugene O.; Savard, Maxime; Verreault, Sonia; Thibault, Simon; Chevrette, Paul C.; Ricard, Benoit

    2002-06-01

    As part of the Infrared Eye project, this article describes the design of large-deviation, achromatic Risley prisms scanning systems operating in the 0.5 - 0.92 and 8 - 9.5 μm spectral regions. Designing these systems is challenging due to the large deviation required (zero - 25 degrees), the large spectral bandwidth and the mechanical constraints imposed by the need to rotate the prisms to any position in 1/30 second. A design approach making extensive use of the versatility of optical design softwares is described. Designs consisting of different pairs of optical materials are shown in order to illustrate the trade-off between chromatic aberration, mass and vignetting. Control of chromatic aberration and reasonable prism shape is obtained over 8 - 9.5 μm with zinc sulfide and germanium. The design is more difficult for the 0.5 - 0.92 μm band. Trade-offs consist in using sapphire with Cleartran« over a reduced bandwidth (0.75 - 0.9 μm ) or acrylic singlets with the Infrared Eye in active mode (0.85 - 0.86 μm). Non-sequential ray-tracing is used to study the effects of fresnelizing one element of the achromat to reduce its mass, and to evaluate detector narcissus in the 8 - 9.5 μm region.

  15. Ultra-broadband achromatic imaging with diffractive photon sieves

    PubMed Central

    Zhao, Xiaonan; Hu, Jingpei; Lin, Yu; Xu, Feng; Zhu, Xiaojun; Pu, Donglin; Chen, Linsen; Wang, Chinhua

    2016-01-01

    Diffractive optical elements suffer from large chromatic aberration due to the strong wavelength-dependent nature in diffraction phenomena, and therefore, diffractive elements can work only at a single designed wavelength, which significantly limits the applications of diffractive elements in imaging. Here, we report on a demonstration of a wavefront coded broadband achromatic imaging with diffractive photon sieves. The broadband diffraction imaging is implemented with a wavefront coded pinhole pattern that generates equal focusing power for a wide range of operating wavelength in a single thin-film element without complicated auxiliary optical system. Experimental validation was performed using an UV-lithography fabricated wavefront coded photon sieves. Results show that the working bandwidth of the wavefront coded photon sieves reaches 28 nm compared with 0.32 nm of the conventional one. Further demonstration of the achromatic imaging with a bandwidth of 300 nm is also performed with a wavefront coded photon sieves integrated with a refractive element. PMID:27328713

  16. A new human perception-based over-exposure detection method for color images.

    PubMed

    Yoon, Yeo-Jin; Byun, Keun-Yung; Lee, Dae-Hong; Jung, Seung-Won; Ko, Sung-Jea

    2014-09-15

    To correct an over-exposure within an image, the over-exposed region (OER) must first be detected. Detecting the OER accurately has a significant effect on the performance of the over-exposure correction. However, the results of conventional OER detection methods, which generally use the brightness and color information of each pixel, often deviate from the actual OER perceived by the human eye. To overcome this problem, in this paper, we propose a novel method for detecting the perceived OER more accurately. Based on the observation that recognizing the OER in an image is dependent on the saturation sensitivity of the human visual system (HVS), we detect the OER by thresholding the saturation value of each pixel. Here, a function of the proposed method, which is designed based on the results of a subjective evaluation on the saturation sensitivity of the HVS, adaptively determines the saturation threshold value using the color and the perceived brightness of each pixel. Experimental results demonstrate that the proposed method accurately detects the perceived OER, and furthermore, the over-exposure correction can be improved by adopting the proposed OER detection method.

  17. "The normative idea of queer is a white person": understanding perceptions of white privilege among lesbian, bisexual, and queer women of color in Toronto, Canada.

    PubMed

    Logie, Carmen H; Rwigema, Marie-Jolie

    2014-01-01

    White privilege constructs whiteness as normative and central to lesbian, gay, bisexual, and queer (LGBQ) identities and is reproduced through social norms, media representations, and daily interactions. We aimed to enhance understanding of the processes by which white privilege was experienced among lesbian, bisexual, and queer (LBQ) women of color in Toronto, Canada. We conducted two focus groups with LBQ women of color, one with participants who self-identified as masculine of center (n = 8) and the second with participants who identified as feminine of center (n = 8). Findings indicate that LBQ women of color experience intersectional stigma (e.g., homophobia, racism, sexism) on a daily basis. Participant narratives revealed that white privilege shaped the representations of women of color in a particular way that promoted their exclusion from white LBQ spaces and broader society. By representing queerness as white, LBQ women of color were rendered invisible in both queer and racialized communities. LBQ women of color were further marginalized by constructions of "real" women as passive, feminine and white, and conversely perceptions of women of color as aggressive, emotional, and hypersexualized. These representations inform spatialized practices and social interactions through constructing racialized communities as discriminatory and "backwards" while maintaining the invisibility of white privilege and racism in LBQ spaces.

  18. Full Color Rainbow Hologram Using A Photoresist Plate

    NASA Astrophysics Data System (ADS)

    Ohnuma, Kazuhiko; Nishihara, Takashi; Iwata, Fujio

    1989-05-01

    A new method of full color rainbow hologram which can reconstruct a natural color image is developed and has been shown in Applied Optics. This method uses a technique of achromatic holographic stereogram invented by Benton and is realized by only one wavelength of Argon-ion laser and a photoresist plate. It is found from the result of experiments that the reconstructed image has sufficient contrast and wide range of color reproduction in both bright and dark area.

  19. Sound Richness of Music Might Be Mediated by Color Perception: A PET Study

    PubMed Central

    Satoh, Masayuki; Nagata, Ken; Tomimoto, Hidekazu

    2015-01-01

    Objects. We investigated the role of the fusiform cortex in music processing with the use of PET, focusing on the perception of sound richness. Method. Musically naïve subjects listened to familiar melodies with three kinds of accompaniments: (i) an accompaniment composed of only three basic chords (chord condition), (ii) a simple accompaniment typically used in traditional music text books in elementary school (simple condition), and (iii) an accompaniment with rich and flowery sounds composed by a professional composer (complex condition). Using a PET subtraction technique, we studied changes in regional cerebral blood flow (rCBF) in simple minus chord, complex minus simple, and complex minus chord conditions. Results. The simple minus chord, complex minus simple, and complex minus chord conditions regularly showed increases in rCBF at the posterior portion of the inferior temporal gyrus, including the LOC and fusiform gyrus. Conclusions. We may conclude that certain association cortices such as the LOC and the fusiform cortex may represent centers of multisensory integration, with foreground and background segregation occurring at the LOC level and the recognition of richness and floweriness of stimuli occurring in the fusiform cortex, both in terms of vision and audition. PMID:26525171

  20. Optical properties of dental restorative materials in the wavelength range 400 to 700 nm for the simulation of color perception

    NASA Astrophysics Data System (ADS)

    Friebel, Moritz; Povel, Kirsten; Cappius, Hans-Joachim; Helfmann, Jürgen; Meinke, Martina

    2009-09-01

    Aesthetic restorations require dental restorative materials to have optical properties very similar to those of the teeth. A method is developed to this end to determine the optical parameters absorption coefficient μa, scattering coefficient μs, anisotropy factor g, and effective scattering coefficient μs' of dental restorative materials. The method includes sample preparation and measurements of transmittance and reflectance in an integrating sphere spectrometer followed by inverse Monte Carlo simulations. Using this method the intrinsic optical parameters are determined for shade B2 of the light-activated composites TPH® Spectrum®, Esthet-X®, and the Ormocer® Definite® in the wavelength range 400 to 700 nm. By using the determined parameters μa, μs, and g together with an appropriate phase function, the reflectance of samples with 1-mm layer thickness and shade B2 could be predicted with a very high degree of accuracy using a forward Monte Carlo simulation. The color perception was calculated from the simulated reflectance according to the CIELAB system. We initiate the compilation of a data pool of optical parameters that in the future will enable calculation models to be used as a basis for optimization of the optical approximation of the natural tooth, and the composition of new materials and their production process.

  1. Optical properties of dental restorative materials in the wavelength range 400 to 700 nm for the simulation of color perception.

    PubMed

    Friebel, Moritz; Povel, Kirsten; Cappius, Hans-Joachim; Helfmann, Jürgen; Meinke, Martina

    2009-01-01

    Aesthetic restorations require dental restorative materials to have optical properties very similar to those of the teeth. A method is developed to this end to determine the optical parameters absorption coefficient mu(a), scattering coefficient mu(s), anisotropy factor g, and effective scattering coefficient mu(s) (') of dental restorative materials. The method includes sample preparation and measurements of transmittance and reflectance in an integrating sphere spectrometer followed by inverse Monte Carlo simulations. Using this method the intrinsic optical parameters are determined for shade B2 of the light-activated composites TPH((R)) Spectrum, Esthet-X, and the Ormocer Definite in the wavelength range 400 to 700 nm. By using the determined parameters mu(a), mu(s), and g together with an appropriate phase function, the reflectance of samples with 1-mm layer thickness and shade B2 could be predicted with a very high degree of accuracy using a forward Monte Carlo simulation. The color perception was calculated from the simulated reflectance according to the CIELAB system. We initiate the compilation of a data pool of optical parameters that in the future will enable calculation models to be used as a basis for optimization of the optical approximation of the natural tooth, and the composition of new materials and their production process.

  2. Dynamic egg color mimicry.

    PubMed

    Hanley, Daniel; Šulc, Michal; Brennan, Patricia L R; Hauber, Mark E; Grim, Tomáš; Honza, Marcel

    2016-06-01

    Evolutionary hypotheses regarding the function of eggshell phenotypes, from solar protection through mimicry, have implicitly assumed that eggshell appearance remains static throughout the laying and incubation periods. However, recent research demonstrates that egg coloration changes over relatively short, biologically relevant timescales. Here, we provide the first evidence that such changes impact brood parasite-host eggshell color mimicry during the incubation stage. First, we use long-term data to establish how rapidly the Acrocephalus arundinaceus Linnaeus (great reed warbler) responded to natural parasitic eggs laid by the Cuculus canorus Linnaeus (common cuckoo). Most hosts rejected parasitic eggs just prior to clutch completion, but the host response period extended well into incubation (~10 days after clutch completion). Using reflectance spectrometry and visual modeling, we demonstrate that eggshell coloration in the great reed warbler and its brood parasite, the common cuckoo, changes rapidly, and the extent of eggshell color mimicry shifts dynamically over the host response period. Specifically, 4 days after being laid, the host should notice achromatic color changes to both cuckoo and warbler eggs, while chromatic color changes would be noticeable after 8 days. Furthermore, we demonstrate that the perceived match between host and cuckoo eggshell color worsened over the incubation period. These findings have important implications for parasite-host coevolution dynamics, because host egg discrimination may be aided by disparate temporal color changes in host and parasite eggs.

  3. Complete achromatic optical switching between two waveguides with a sign flip of the phase mismatch

    NASA Astrophysics Data System (ADS)

    Huang, Wei; Rangelov, Andon A.; Kyoseva, Elica

    2014-11-01

    We present a two-waveguide coupler which realizes complete achromatic all-optical switching. The coupling of the waveguides has a hyperbolic-secant shape, while the phase mismatch has a sign flip at the maximum of the coupling. We derive an analytic solution for the electric field propagation using coupled-mode theory and show that the light switching is robust against small to moderate variations in the coupling strength and phase mismatch. Thus, we realize an achromatic light switching between the two waveguides. We further consider the extended case of three coupled waveguides in an array and pay special attention to the case of equal bidirectional achromatic light beam splitting.

  4. COMPARISON OF DOUBLE BEND AND TRIPLE BEND ACHROMATIC LATTICE STRUCTURES AND NSLS-II.

    SciTech Connect

    KRAMER, S.L.; KRINSKY, S.; BENGTSSON, J.

    2006-06-26

    The Double Bend Achromatic (DBA) and the Triple Bend Achromatic (TBA) lattice have been studied rather extensively for use for the NSLS-II storage ring. The advantage of the TBA compared to the DBA in terms of emittance per period is well known. However, the DBA has the advantage of greater number of ID straight sections for the users and maybe easier to tune the dispersive section for reduced chromatic sextupole strength. We present a comparison of these lattices based on optimization of the non-linear driving terms using high order achromatic cancellation of driving terms of the nonlinear lattice.

  5. Symmetric Achromatic Low-Beta Collider Interaction Region Design Concept

    SciTech Connect

    Morozov, Vasiliy S.; Derbenev, Yaroslav S.; Lin, Fanglei; Johnson, Rolland P.

    2013-01-01

    We present a new symmetry-based concept for an achromatic low-beta collider interaction region design. A specially-designed symmetric Chromaticity Compensation Block (CCB) induces an angle spread in the passing beam such that it cancels the chromatic kick of the final focusing quadrupoles. Two such CCB?s placed symmetrically around an interaction point allow simultaneous compensation of the 1st-order chromaticities and chromatic beam smear at the IP without inducing significant 2nd-order aberrations. We first develop an analytic description of this approach and explicitly formulate 2nd-order aberration compensation conditions at the interaction point. The concept is next applied to develop an interaction region design for the ion collider ring of an electron-ion collider. We numerically evaluate performance of the design in terms of momentum acceptance and dynamic aperture. The advantages of the new concept are illustrated by comparing it to the conventional distributed-sextupole chromaticity compensation scheme.

  6. True colors - changing perceptions of hydrological processes at a hillslope prone to slide

    NASA Astrophysics Data System (ADS)

    Schneider, P.; Strouhal, L.; Pool, S.; Seibert, J.

    2013-06-01

    This study investigated runoff formation processes of a pre-alpine hillslope prone to slide. The experimental pasture plot (40 m × 60 m) is located in the northern front range of the Swiss Alps on a 30° steep hillslope (1180 m a.s.l., 1500+ mm annual precipitation). A gleysol (H-Go-Gr) overlies weathered marlstone and conglomerate of subalpine molasse. We conducted sprinkling experiments on a subplot (10 m × 10 m) with variable rainfall intensities. During both experiments fluorescein line-tracer injections into the topsoil, and sodium chloride (NaCl) injections into the sprinkling water were used to monitor flow velocities in the soil. The observed flow velocities for fluorescein in the soil were 1.2 and 1.4 × 10-3 m s-1. The NaCl breakthrough occurred almost simultaneously in all monitored discharge levels (0.05, 0.25 and 1 m depth), indicating a high infiltration capacity and efficient drainage of the soil. These initial observations suggested "transmissivity feedback", a form of subsurface stormflow, as the dominant runoff process. However, the results of a brilliant blue dye tracer experiment completely changed our perceptions of the hillslope's hydrological processes. Excavation of the dye-stained soils highlighted the dominance of "organic layer interflow", a form of shallow subsurface stormflow. The dye stained the entire H horizon, vertical soil fractures, and macropores (mostly worm burrows) up to 50 cm depth. Lateral drainage in the subsoil or at the soil-bedrock interface was not observed, and thus was limited to the organic topsoil. In the context of shallow landslides, the subsoil (Go/Gr) acted as an infiltration and exfiltration barrier, which produced significant lateral saturated drainage in the topsoil (H) and possibly a confined aquifer in the bedrock.

  7. Percept

    SciTech Connect

    2014-11-26

    The Percept software package is a collection of libraries and executables that provide tools for verifying computer simulations of engineering components and systems. Percept is useful for simulations using the finite element or finite volume methods on unstructured meshes. Percept includes API's for adaptive mesh refinement, geometry representation, the method of manufactured solutions, analysis of convergence including the convergence of vibrational eigenmodes, and metrics for analyzing the difference between fields represented on two different overlapping unstructured grids.

  8. Wide-band achromatic flat focusing lens based on all-dielectric subwavelength metasurface.

    PubMed

    Wang, Shaowu; Lai, Jianjun; Wu, Tao; Chen, Changhong; Sun, Junqiang

    2017-03-20

    A new method for realizing achromatic flat focusing based on all-dielectric silicon subwavelength metasurface is presented. The designed subwavelength silicon-air slits waveguide array with varied widths can provide desired phase shift of beam focusing and has the non-dispersive characteristic when the period of each unit cell is far less than the wavelength of incident electromagnetic wave (about λ/10) in mid-infrared and far-infrared spectral range. Numerical simulation of an achromatic flat focusing lens in wide spectral range from 8μm to 12μm is performed by the finite difference time domain method and the results show agreement with theory analysis results. This work indicates an effective solution for wide-band achromatic flat optical elements and potential application in integrated achromatic infrared optical systems.

  9. Non-cardinal color perception across the retina: easy for orange, hard for burgundy and sky blue.

    PubMed

    Gunther, Karen L

    2014-04-01

    Cardinal color performance (reddish, greenish, bluish, yellowish, black, and white) has been shown to decline in peripheral viewing. What about non-cardinal color performance (e.g., orange, burgundy, and sky blue)? In visual search, performance on non-cardinal colors matched that of the cardinal colors in the (L-M)/(S-(L+M)) (isoluminant) color plane (Experiment 1, n=10, to 30°; Experiment 2, n=3, to 50°). However, performance in the (L-M)/(L+M) and (S-(L+M))/(L+M) color planes was worse for non-cardinal colors, at all eccentricities, even in the fovea. The implications that these results have for the existence of non-cardinal mechanisms in each color plane are discussed.

  10. Precision of synesthetic color matching resembles that for recollected colors rather than physical colors.

    PubMed

    Arnold, Derek H; Wegener, Signy V; Brown, Francesca; Mattingley, Jason B

    2012-10-01

    Grapheme-color synesthesia is an atypical condition in which individuals experience sensations of color when reading printed graphemes such as letters and digits. For some grapheme-color synesthetes, seeing a printed grapheme triggers a sensation of color, but hearing the name of a grapheme does not. This dissociation allowed us to compare the precision with which synesthetes are able to match their color experiences triggered by visible graphemes, with the precision of their matches for recalled colors based on the same graphemes spoken aloud. In six synesthetes, color matching for printed graphemes was equally variable relative to recalled experiences. In a control experiment, synesthetes and age-matched controls either matched the color of a circular patch while it was visible on a screen, or they judged its color from memory after it had disappeared. Both synesthetes and controls were more variable when matching from memory, and the variance of synesthetes' recalled color judgments matched that associated with their synesthetic judgments for visible graphemes in the first experiment. Results suggest that synesthetic experiences of color triggered by achromatic graphemes are analogous to recollections of color.

  11. Toward a No-Reference Image Quality Assessment Using Statistics of Perceptual Color Descriptors.

    PubMed

    Lee, Dohyoung; Plataniotis, Konstantinos N

    2016-08-01

    Analysis of the statistical properties of natural images has played a vital role in the design of no-reference (NR) image quality assessment (IQA) techniques. In this paper, we propose parametric models describing the general characteristics of chromatic data in natural images. They provide informative cues for quantifying visual discomfort caused by the presence of chromatic image distortions. The established models capture the correlation of chromatic data between spatially adjacent pixels by means of color invariance descriptors. The use of color invariance descriptors is inspired by their relevance to visual perception, since they provide less sensitive descriptions of image scenes against viewing geometry and illumination variations than luminances. In order to approximate the visual quality perception of chromatic distortions, we devise four parametric models derived from invariance descriptors representing independent aspects of color perception: 1) hue; 2) saturation; 3) opponent angle; and 4) spherical angle. The practical utility of the proposed models is examined by deploying them in our new general-purpose NR IQA metric. The metric initially estimates the parameters of the proposed chromatic models from an input image to constitute a collection of quality-aware features (QAF). Thereafter, a machine learning technique is applied to predict visual quality given a set of extracted QAFs. Experimentation performed on large-scale image databases demonstrates that the proposed metric correlates well with the provided subjective ratings of image quality over commonly encountered achromatic and chromatic distortions, indicating that it can be deployed on a wide variety of color image processing problems as a generalized IQA solution.

  12. The modern Japanese color lexicon.

    PubMed

    Kuriki, Ichiro; Lange, Ryan; Muto, Yumiko; Brown, Angela M; Fukuda, Kazuho; Tokunaga, Rumi; Lindsey, Delwin T; Uchikawa, Keiji; Shioiri, Satoshi

    2017-03-01

    Despite numerous prior studies, important questions about the Japanese color lexicon persist, particularly about the number of Japanese basic color terms and their deployment across color space. Here, 57 native Japanese speakers provided monolexemic terms for 320 chromatic and 10 achromatic Munsell color samples. Through k-means cluster analysis we revealed 16 statistically distinct Japanese chromatic categories. These included eight chromatic basic color terms (aka/red, ki/yellow, midori/green, ao/blue, pink, orange, cha/brown, and murasaki/purple) plus eight additional terms: mizu ("water")/light blue, hada ("skin tone")/peach, kon ("indigo")/dark blue, matcha ("green tea")/yellow-green, enji/maroon, oudo ("sand or mud")/mustard, yamabuki ("globeflower")/gold, and cream. Of these additional terms, mizu was used by 98% of informants, and emerged as a strong candidate for a 12th Japanese basic color term. Japanese and American English color-naming systems were broadly similar, except for color categories in one language (mizu, kon, teal, lavender, magenta, lime) that had no equivalent in the other. Our analysis revealed two statistically distinct Japanese motifs (or color-naming systems), which differed mainly in the extension of mizu across our color palette. Comparison of the present data with an earlier study by Uchikawa & Boynton (1987) suggests that some changes in the Japanese color lexicon have occurred over the last 30 years.

  13. Do graphemes attract spatial attention in grapheme-color synesthesia?

    PubMed

    Volberg, G; Chockley, A S; Greenlee, M W

    2017-03-03

    Grapheme-color synesthetes perceive concurrent colors for some objectively achromatic graphemes (inducers). Using oscillatory responses in the electroencephalogram, we tested the hypothesis that inducers automatically attract spatial attention and, thus, favor a conscious experience of color. Achromatic inducers and real-colored non-inducers were presented to the left or to the right visual hemifield and orientation judgments were required for subsequently presented Gabor patches. The graphemes were irrelevant for the task so that the related brain response was purely stimulus-driven. Synesthetes (n =12), but not an equal number of controls, showed an early theta power increase for inducers presented to the right compared to the left hemifield, with sources in left fusiform gyrus. Alpha power asymmetries indicative of shifts of spatial attention were not observed. Together, synesthetes showed an increased responsiveness to inducers in grapheme processing areas. However, contrary to our hypothesis, inducers did not attract spatial attention in synesthetes.

  14. Achromatic Focal Plane Mask for Exoplanet Imaging Coronagraphy

    NASA Technical Reports Server (NTRS)

    Newman, Kevin Edward; Belikov, Ruslan; Guyon, Olivier; Balasubramanian, Kunjithapatham; Wilson, Dan

    2013-01-01

    Recent advances in coronagraph technologies for exoplanet imaging have achieved contrasts close to 1e10 at 4 lambda/D and 1e-9 at 2 lambda/D in monochromatic light. A remaining technological challenge is to achieve high contrast in broadband light; a challenge that is largely limited by chromaticity of the focal plane mask. The size of a star image scales linearly with wavelength. Focal plane masks are typically the same size at all wavelengths, and must be sized for the longest wavelength in the observational band to avoid starlight leakage. However, this oversized mask blocks useful discovery space from the shorter wavelengths. We present here the design, development, and testing of an achromatic focal plane mask based on the concept of optical filtering by a diffractive optical element (DOE). The mask consists of an array of DOE cells, the combination of which functions as a wavelength filter with any desired amplitude and phase transmission. The effective size of the mask scales nearly linearly with wavelength, and allows significant improvement in the inner working angle of the coronagraph at shorter wavelengths. The design is applicable to almost any coronagraph configuration, and enables operation in a wider band of wavelengths than would otherwise be possible. We include initial results from a laboratory demonstration of the mask with the Phase Induced Amplitude Apodization coronagraph.

  15. CIAXE: co-axial achromatic interferential coronagraph: first laboratory results

    NASA Astrophysics Data System (ADS)

    Allouche, Fatmé; Gay, Jean; Rabbia, Yves; Assus, Pierre

    2010-07-01

    In 1996, Jean Gay and Yves Rabbia presented their Achromatic Interferential Coronagraph (AIC) for detecting and imaging faint companions (ultimately exoplanets) in the neighboring of a star. As presented then, the Michleson-like Interferometer configuration of the AIC hardens its insertion into an existing (coaxial) optical train, the output beam of the AIC being delivered at right angle from the input beam. To overcome this, they reconfigured the AIC into a compact and fully axial coronagraph, the CIAXE, which main feature consists of using two thick lenses machined in the same optical material. For the CIAXE to deliver the output beam along the same axis as the input beam, the two lenses are coaxially disposed on the optical axis and are separated, at their common spherical contact surface by a thin air gap acting like a beam splitter. We have set up a laboratory experiment aiming at validating the principle of the concept. Our first step was to equalize the thicknesses of the two lenses, so as to make zero the optical path difference between both arms. For this, the (residual) value of the OPD has been evaluated and then the lenses have been re-machined so as to decrease as far as technologically possible, the thicknesses mismatch. As a second step, a micro-controlled rotation around the common curvature center of the spherical surfaces of the lenses is applied. This allows a fine tuning of the residual OPD at the required accuracy level. Are presented here test bench, steps and results.

  16. Beauty and the teeth: perception of tooth color and its influence on the overall judgment of facial attractiveness.

    PubMed

    Höfel, Lea; Lange, Matthias; Jacobsen, Thomas

    2007-08-01

    This study investigated the influence of changes in tooth color on judgments of facial attractiveness. Standardized photographs were presented, and teeth were digitally manipulated (main categories: original, whitened, colored; filler category: impaired). Participants were instructed to evaluate the faces for attractiveness. Additionally, they were asked to name facial features they found either positive or negative with regard to attractiveness. Whitened teeth were mentioned more often in a positive way but did not improve participants' assessment of attractiveness. A colored tooth did not attract attention, and the attractiveness judgment did not worsen. Tooth color is thus not necessarily perceived and does not have a major impact on facial attractiveness.

  17. LGB of Color and White Individuals' Perceptions of Heterosexist Stigma, Internalized Homophobia, and Outness: Comparisons of Levels and Links

    ERIC Educational Resources Information Center

    Moradi, Bonnie; Wiseman, Marcie C.; DeBlaere, Cirleen; Goodman, Melinda B.; Sarkees, Anthony; Brewster, Melanie E.; Huang, Yu-Ping

    2010-01-01

    Conceptual discussions about LGB people of color suggest that, compared with White LGB individuals, LGB people of color may be exposed to greater levels of heterosexist stigma and its deleterious correlates (greater risk) or may be more resilient to such stigma (resilience). This study tested tenets of these two perspectives with a sample of 178…

  18. Broadband Achromatic Phase Shifter for a Nulling Interferometer

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Lyon, Richard G.

    2011-01-01

    Nulling interferometry is a technique for imaging exoplanets in which light from the parent star is suppressed using destructive interference. Light from the star is divided into two beams and a phase shift of radians is introduced into one of the beams. When the beams are recombined, they destructively interfere to produce a deep null. For monochromatic light, this is implemented by introducing an optical path difference (OPD) between the two beams equal to lambda/2, where lambda is the wavelength of the light. For broadband light, however, a different phase shift will be introduced at each wavelength and the two beams will not effectively null when recombined. Various techniques have been devised to introduce an achromatic phase shift a phase shift that is uniform across a particular bandwidth. One popular technique is to use a series of dispersive elements to introduce a wavelength-dependent optical path in one or both of the arms of the interferometer. By intelligently choosing the number, material and thickness of a series of glass plates, a nearly uniform, arbitrary phase shift can be introduced between two arms of an interferometer. There are several constraints that make choosing the number, type, and thickness of materials a difficult problem, such as the size of the bandwidth to be nulled. Several solutions have been found for bandwidths on the order of 20 to 30 percent (Delta(lambda)/lambda(sub c)) in the mid-infrared region. However, uniform phase shifts over a larger bandwidth in the visible regime between 480 to 960 nm (67 percent) remain difficult to obtain at the tolerances necessary for exoplanet detection. A configuration of 10 dispersive glass plates was developed to be used as an achromatic phase shifter in nulling interferometry. Five glass plates were placed in each arm of the interferometer and an additional vacuum distance was also included in the second arm of the interferometer. This configuration creates a phase shift of pi radians with

  19. A new perceptual problem: the amodal completion of color.

    PubMed

    Pinna, Baingio

    2008-01-01

    Amodal completion is the most common form of visual completion occurring when portions of an object are hidden, due to their occlusion behind another object (Michotte, 1951). Just as a shape is completed amodally behind another occluding shape, so is a color behind another occluding color or behind a lighting: a bright light reflected by a three-dimensional object. Four possible phenomenal combinations related to the amodal completion of color are shown: amodal or modal coloration or discoloration. Purposes of four experiments were: (1) to demonstrate the amodal completion of color under different stimulus conditions and under chromatic and achromatic conditions and (2) to extract the general principles ruling the amodal completion of color: "which, among many, is the color that completes amodally?" and, consequently, "which is the region of an object that determines its color?" The results showed the effectiveness of the amodal completion of color and that chromatic and achromatic conditions reveal different results. Four general principles of the amodal completion of color, useful to understand the more general problem of phenomenal organization of color, are suggested.

  20. Chromatic-achromatic perimetry in four clinic cases: Glaucoma and diabetes

    PubMed Central

    Cabezos, Inmaculada; Luque, Maria José; de Fez, Dolores; Moncho, Vicenta; Camps, Vicente

    2015-01-01

    Background: Some diseases that affect the visual system may show loss of chromatic-achromatic sensitivity before obvious physical signs appear in the usual examination of the eye's posterior segment. A perimetric study has been conducted with four typical patients with glaucoma and diabetes, at different stages of the disease. Materials and Methods: In addition to the standard white-on-white (standard automated perimetry [SAP]), a test battery has been used to study patient's contrast sensitivity, using stimuli with different chromatic, spatial, and temporal content (multichannel perimetry). The choice of stimuli tries to maximize the response of different visual mechanisms: Achromatic (parvocellular and magnocellular origin); chromatic red-green (parvocellular origin); and chromatic blue-yellow (koniocellular origin). Results: The results seem to indicate losses in the achromatic-parvocellular perimetry and both chromatic perimetry tests, undetected by conventional SAP. Conclusions: Our results illustrate that our patients without visible retinal alterations show signs of suspicion in multichannel perimetry. PMID:25827546

  1. An infrared achromatic quarter-wave plate designed based on simulated annealing algorithm

    NASA Astrophysics Data System (ADS)

    Pang, Yajun; Zhang, Yinxin; Huang, Zhanhua; Yang, Huaidong

    2017-03-01

    Quarter-wave plates are primarily used to change the polarization state of light. Their retardation usually varies depending on the wavelength of the incident light. In this paper, the design and characteristics of an achromatic quarter-wave plate, which is formed by a cascaded system of birefringent plates, are studied. For the analysis of the combination, we use Jones matrix method to derivate the general expressions of the equivalent retardation and the equivalent azimuth. The infrared achromatic quarter-wave plate is designed based on the simulated annealing (SA) algorithm. The maximum retardation variation and the maximum azimuth variation of this achromatic waveplate are only about 1.8 ° and 0.5 ° , respectively, over the entire wavelength range of 1250-1650 nm. This waveplate can change the linear polarized light into circular polarized light with a less than 3.2% degree of linear polarization (DOLP) over that wide wavelength range.

  2. Achrotech: achromat cost versus performance for conventional, diffractive, and GRIN components

    NASA Astrophysics Data System (ADS)

    Morris, Jeffrey; Wolf, Greg; Vandendriessche, Stefaan; Sparrold, Scott

    2016-09-01

    An achromatic component shares a common focus at two wavelengths and is a commonly used device in optical assemblies. This work explores the cost versus performance tradeoff for several types of achromatic lenses: conventional doublets with homogenous glass elements, hybrid doublets with a diffractive surface, axial GRadient INdex (GRIN) lenses (where the index of refraction changes along the length of the lens), and radial GRIN lenses (where the index of refraction changes depending on radial position). First order achromatic principles will be reviewed and applied to each system as a starting point and refined through the use of ray trace software. Optical performance will be assessed in terms of focusing efficiency and imaging. Cost will then be evaluated by accounting for current manufacturing costs and retail price through several distributors.

  3. Achromatic interfero-coronagraph with variable rotational shear in laboratory experiments

    NASA Astrophysics Data System (ADS)

    Frolov, Pavel; Kiselev, Alexander; Tavrov, Alexander

    2016-07-01

    Direct imaging of earth-like extrasolar planets in the habitable zone and the search for possible biological signatures are among the key scientific objectives in the modern astronomy. Stellar coronagraph such as achromatic interfero coronagraph (AIC) with a small inner working angle has limited possibilities to detect and characterize planets around nearby stars due to the star leakage effect caused by incomplete suppression of the star of finite angular size. We report on an improved instrument for direct imaging of exoplanets and the study of stellar environment - common-path achromatic interfero-coronagraph with variable rotational shear (common-path achromatic rotation-shearing coronagraph, CP-ARC) - a common path implementation of rotation shearing interferometer. We detail CP-ARC approach and discuss its optical configuration, laboratory prototype and experimental results.

  4. Eigenvectors of optimal color spectra.

    PubMed

    Flinkman, Mika; Laamanen, Hannu; Tuomela, Jukka; Vahimaa, Pasi; Hauta-Kasari, Markku

    2013-09-01

    Principal component analysis (PCA) and weighted PCA were applied to spectra of optimal colors belonging to the outer surface of the object-color solid or to so-called MacAdam limits. The correlation matrix formed from this data is a circulant matrix whose biggest eigenvalue is simple and the corresponding eigenvector is constant. All other eigenvalues are double, and the eigenvectors can be expressed with trigonometric functions. Found trigonometric functions can be used as a general basis to reconstruct all possible smooth reflectance spectra. When the spectral data are weighted with an appropriate weight function, the essential part of the color information is compressed to the first three components and the shapes of the first three eigenvectors correspond to one achromatic response function and to two chromatic response functions, the latter corresponding approximately to Munsell opponent-hue directions 9YR-9B and 2BG-2R.

  5. Status of Studies of Achromat-based 6D Ionization Cooling Rings for Muons

    SciTech Connect

    Ding, X.; Kirk, H.; Cline, D.; Garren, A.A.; Berg, J.S.

    2011-09-04

    Six dimensional ionization cooling of muons is needed to achieve the necessary luminosity for a muon collider. If that cooling could occur over multiple turns in a closed ring, there would be significant cost savings over a single-pass cooling channel. We report on the status of a cooling ring with achromatic arcs. The achromatic design permits the design to easily switch between a closed ring and a snaking geometry on injection or extraction from the ring. The ring is designed with sufficient space in each superperiod for injection and extraction magnets. We describe the ring's lattice design, performance, and injection/extraction requirements.

  6. Examining the Relationship Between Schizotypy and Self-Reported Visual Imagery Vividness in Grapheme-Color Synaesthesia

    PubMed Central

    Janik McErlean, Agnieszka B.; Banissy, Michael J.

    2016-01-01

    Synaesthesia is a condition in which one property of a stimulus triggers a secondary experience not typically associated with the first (e.g., seeing achromatic graphemes can evoke the perception of color). Recent work has explored a variety of cognitive and perceptual traits associated with synaesthesia. One example is in the domain of personality, where higher rates of positive schizotypy and openness to experience and lower agreeableness have been reported in synaesthetes who experience color as their evoked sensation relative to typical adult controls. Additionally, grapheme-color synaesthetes have previously been reported to show elevated mental imagery compared to typical adults. Here, we aimed to further elucidate the relationship between personality, synaesthesia, and other cognitive traits. In Study 1, we examined self-reported schizotypy and self-reported visual imagery vividness in grapheme-color synaesthetes and typical adults. Our results partially replicated previous findings by showing that synaesthesia was associated with greater positive schizotypy and enhanced self-reported imagery vividness. The results also extend previous reports by demonstrating that differences in positive schizotypy and mental imagery vividness are not related in grapheme-color synaesthesia. In Study 2, we sought to build on prior work showing lower agreeableness and increased openness to experience in synaesthetes by examining whether grapheme-color synaesthesia is associated with other conceptually related traits; namely lower self-monitoring and increased sensation seeking. We did not find any differences between synaesthetes and controls on either of these traits. These findings are discussed in relation to potential factors that may contribute to the observed personality profile in grapheme-color synaesthesia. PMID:26973548

  7. Priming letters by colors: evidence for the bidirectionality of grapheme-color synesthesia.

    PubMed

    Weiss, Peter H; Kalckert, Andreas; Fink, Gereon R

    2009-10-01

    In synesthesia, stimulation of one sensory modality leads to a percept in another nonstimulated modality, for example, graphemes trigger an additional color percept in grapheme-color synesthesia, which encompasses the variants letter-color and digit-color synesthesia. Until recently, it was assumed that synesthesia occurs strictly unidirectional: Although the perception of a letter induces a color percept in letter-color synesthetes, they typically do not report that colors trigger the percept of a letter. Recent data on number processing in synesthesia suggest, however, that colors can implicitly elicit numerical representations in digit-color synesthetes, thereby questioning unidirectional models of synesthesia. Using a word fragment completion paradigm in 10 letter-color synesthetes, we show here for the first time that colors can implicitly influence lexical search. Our data provide strong support for a bidirectional nature of grapheme-color synesthesia and, in general, may allude to the mechanisms of cross-modality interactions in the human brain.

  8. Enhanced Fine-Form Perception Does Not Contribute to Gestalt Face Perception in Autism Spectrum Disorder

    PubMed Central

    Maekawa, Toshihiko; Miyanaga, Yuka; Takahashi, Kenji; Takamiya, Naomi; Ogata, Katsuya; Tobimatsu, Shozo

    2017-01-01

    Individuals with autism spectrum disorder (ASD) show superior performance in processing fine detail, but often exhibit impaired gestalt face perception. The ventral visual stream from the primary visual cortex (V1) to the fusiform gyrus (V4) plays an important role in form (including faces) and color perception. The aim of this study was to investigate how the ventral stream is functionally altered in ASD. Visual evoked potentials were recorded in high-functioning ASD adults (n = 14) and typically developing (TD) adults (n = 14). We used three types of visual stimuli as follows: isoluminant chromatic (red/green, RG) gratings, high-contrast achromatic (black/white, BW) gratings with high spatial frequency (HSF, 5.3 cycles/degree), and face (neutral, happy, and angry faces) stimuli. Compared with TD controls, ASD adults exhibited longer N1 latency for RG, shorter N1 latency for BW, and shorter P1 latency, but prolonged N170 latency, for face stimuli. Moreover, a greater difference in latency between P1 and N170, or between N1 for BW and N170 (i.e., the prolongation of cortico-cortical conduction time between V1 and V4) was observed in ASD adults. These findings indicate that ASD adults have enhanced fine-form (local HSF) processing, but impaired color processing at V1. In addition, they exhibit impaired gestalt face processing due to deficits in integration of multiple local HSF facial information at V4. Thus, altered ventral stream function may contribute to abnormal social processing in ASD. PMID:28146575

  9. Enhanced Fine-Form Perception Does Not Contribute to Gestalt Face Perception in Autism Spectrum Disorder.

    PubMed

    Yamasaki, Takao; Maekawa, Toshihiko; Miyanaga, Yuka; Takahashi, Kenji; Takamiya, Naomi; Ogata, Katsuya; Tobimatsu, Shozo

    2017-01-01

    Individuals with autism spectrum disorder (ASD) show superior performance in processing fine detail, but often exhibit impaired gestalt face perception. The ventral visual stream from the primary visual cortex (V1) to the fusiform gyrus (V4) plays an important role in form (including faces) and color perception. The aim of this study was to investigate how the ventral stream is functionally altered in ASD. Visual evoked potentials were recorded in high-functioning ASD adults (n = 14) and typically developing (TD) adults (n = 14). We used three types of visual stimuli as follows: isoluminant chromatic (red/green, RG) gratings, high-contrast achromatic (black/white, BW) gratings with high spatial frequency (HSF, 5.3 cycles/degree), and face (neutral, happy, and angry faces) stimuli. Compared with TD controls, ASD adults exhibited longer N1 latency for RG, shorter N1 latency for BW, and shorter P1 latency, but prolonged N170 latency, for face stimuli. Moreover, a greater difference in latency between P1 and N170, or between N1 for BW and N170 (i.e., the prolongation of cortico-cortical conduction time between V1 and V4) was observed in ASD adults. These findings indicate that ASD adults have enhanced fine-form (local HSF) processing, but impaired color processing at V1. In addition, they exhibit impaired gestalt face processing due to deficits in integration of multiple local HSF facial information at V4. Thus, altered ventral stream function may contribute to abnormal social processing in ASD.

  10. Race relations and racism in the LGBTQ community of Toronto: perceptions of gay and queer social service providers of color.

    PubMed

    Giwa, Sulaimon; Greensmith, Cameron

    2012-01-01

    This article explores race relations and racism within the lesbian, gay, bisexual, transgender, and queer (LGBTQ) community of Toronto, Ontario, from the perspective of seven gay/queer social service providers of color. Social constructions of race, race relations, and racism were placed at the centre of analysis. Employing interpretive phenomenological analysis, findings indicated that intergroup and broader systemic racism infiltrates the LGBTQ community, rendering invisible the lived experiences of many LGBTQ people of color. The study contributes to a growing body of research concerning our understanding of factors underpinning social discrimination in a contemporary Canadian LGBTQ context.

  11. Sub-15fs ultraviolet pulses generated by achromatic phase-matching sum-frequency mixing.

    PubMed

    Zhao, Baozhen; Jiang, Yongliang; Sueda, Keiich; Miyanaga, Noriaki; Kobayashi, Takayoshi

    2009-09-28

    A broadband ultraviolet pulse with a spectral width of 44 nm was generated by achromatic sum-frequency mixing of an 805-nm pulse and ultrabroadband visible pulse. Angular dispersion was introduced to achieve broadband phase matching by a prism pair. The UV pulse was compressed to 13.2 fs with another prism pair, with energy of 600 nJ.

  12. New Light on an Old Question: Who Invented the Achromatic Telescope?

    NASA Astrophysics Data System (ADS)

    Rudd, M. Eugene; Jaecks, Duane H.; Willach, Rolf; Sorrenson, Richard; Abrahams, Peter

    A discussion of the events leading up to the invention of the achromatic telescope, including topics on spherical aberration and Franciscus Maurolycus, the discovery of chromatic aberration, Issac Newton, John Dollond and his experiments, Samuel Klingenstierna, patent trials, and letters from Dollond and Ramsden.

  13. An Investigation of the Perceptions of Low-Income Students of Color Concerning College Costs and Financial Aid Information

    ERIC Educational Resources Information Center

    Waters, Jennifer A.

    2009-01-01

    As college enrollments continue to increase, the disparity between middle-income white students and low-income students of color enrolling in private higher educational institutions continues to widen. Previous research has identified barriers such as access and equity in education, the high cost of education, and limited knowledge regarding…

  14. Performance Evaluation of Color Models in the Fusion of Functional and Anatomical Images.

    PubMed

    Ganasala, Padma; Kumar, Vinod; Prasad, A D

    2016-05-01

    Fusion of the functional image with an anatomical image provides additional diagnostic information. It is widely used in diagnosis, treatment planning, and follow-up of oncology. Functional image is a low-resolution pseudo color image representing the uptake of radioactive tracer that gives the important metabolic information. Whereas, anatomical image is a high-resolution gray scale image that gives structural details. Fused image should consist of all the anatomical details without any changes in the functional content. This is achieved through fusion in de-correlated color model and the choice of color model has greater impact on the fusion outcome. In the present work, suitability of different color models for functional and anatomical image fusion is studied. After converting the functional image into de-correlated color model, the achromatic component of functional image is fused with an anatomical image by using proposed nonsubsampled shearlet transform (NSST) based image fusion algorithm to get new achromatic component with all the anatomical details. This new achromatic and original chromatic channels of functional image are converted to RGB format to get fused functional and anatomical image. Fusion is performed in different color models. Different cases of SPECT-MRI images are used for this color model study. Based on visual and quantitative analysis of fused images, the best color model for the stated purpose is determined.

  15. Color universal design: analysis of color category dependency on color vision type (3)

    NASA Astrophysics Data System (ADS)

    Kojima, Natsuki; Ichihara, Yasuyo G.; Ikeda, Tomohiro; Kamachi, Miyuki G.; Ito, Kei

    2012-01-01

    We report on the results of a study investigating the color perception characteristics of people with red-green color confusion. We believe that this is an important step towards achieving Color Universal Design. In Japan, approximately 5% of men and 0.2% of women have red-green confusion. The percentage for men is higher in Europe and the United States; up to 8% in some countries. Red-green confusion involves a perception of colors different from normal color vision. Colors are used as a means of disseminating clear information to people; however, it may be difficult to convey the correct information to people who have red-green confusion. Consequently, colors should be chosen that minimize accidents and that promote more effective communication. In a previous survey, we investigated color categories common to each color vision type, trichromat (C-type color vision), protan (P-type color vision) and deuteran (D-type color vision). In the present study, first, we conducted experiments in order to verify a previous survey of C-type color vision and P-type color vision. Next, we investigated color difference levels within "CIE 1976 L*a*b*" (the CIELAB uniform color space), where neither C-type nor P-type color vision causes accidents under certain conditions (rain maps/contour line levels and graph color legend levels). As a result, we propose a common chromaticity of colors that the two color vision types are able to categorize by means of color names common to C-type color vision. We also offer a proposal to explain perception characteristics of color differences with normal color vision and red-green confusion using the CIELAB uniform color space. This report is a follow-up to SPIE-IS & T / Vol. 7528 7528051-8 and SPIE-IS & T /vol. 7866 78660J-1-8.

  16. A color hierarchy for automatic target selection.

    PubMed

    Tchernikov, Illia; Fallah, Mazyar

    2010-02-24

    Visual processing of color starts at the cones in the retina and continues through ventral stream visual areas, called the parvocellular pathway. Motion processing also starts in the retina but continues through dorsal stream visual areas, called the magnocellular system. Color and motion processing are functionally and anatomically discrete. Previously, motion processing areas MT and MST have been shown to have no color selectivity to a moving stimulus; the neurons were colorblind whenever color was presented along with motion. This occurs when the stimuli are luminance-defined versus the background and is considered achromatic motion processing. Is motion processing independent of color processing? We find that motion processing is intrinsically modulated by color. Color modulated smooth pursuit eye movements produced upon saccading to an aperture containing a surface of coherently moving dots upon a black background. Furthermore, when two surfaces that differed in color were present, one surface was automatically selected based upon a color hierarchy. The strength of that selection depended upon the distance between the two colors in color space. A quantifiable color hierarchy for automatic target selection has wide-ranging implications from sports to advertising to human-computer interfaces.

  17. Reader Response to Front Pages with Modular Format and Color [and] Newspaper Errors: Source Perception, Reporter Response and Some Causes. American Newspaper Publishers Association (ANPA) News Research Report No. 35.

    ERIC Educational Resources Information Center

    Click, J. W.; And Others

    Two studies were conducted, the first to determine reader response to newspaper front pages with modular format and color, and the second to examine source perception and reporter response to errors in news stories. Results of the first study revealed that respondents in three cities preferred modular front pages to other modern format pages and…

  18. School engagement among urban adolescents of color: does perception of social support and neighborhood safety really matter?

    PubMed

    Daly, Brian P; Shin, Richard Q; Thakral, Charu; Selders, Michael; Vera, Elizabeth

    2009-01-01

    In this study we examined the effects of risk factors (perceived neighborhood crime/delinquency problems, neighborhood incivilities) and protective factors (teacher support, family support, peer support) on the school engagement of 123 urban adolescents of color. Age and gender were also examined to determine if different ages (younger or older) or genders (male or female) significantly modified the relationship between the risk factors and school engagement. Results indicated that perceived neighborhood incivilities was uniquely predictive of school engagement. Contrary to hypotheses, different levels of the perceived social support variables did not modify the effects of risky neighborhood conditions on adolescent's perceived school engagement. Age, but not gender, significantly modified the relationship between perceived family social support and perceived neighborhood crime on adolescents' reported levels of school engagement. The implications of the results for prevention and intervention programs that address school engagement among early adolescents of color are considered.

  19. Evolution of avian plumage color in a tetrahedral color space: a phylogenetic analysis of new world buntings.

    PubMed

    Stoddard, Mary Caswell; Prum, Richard O

    2008-06-01

    We use a tetrahedral color space to describe and analyze male plumage color variation and evolution in a clade of New World buntings--Cyanocompsa and Passerina (Aves: Cardinalidae). The Goldsmith color space models the relative stimulation of the four retinal cones, using the integrals of the product of plumage reflectance spectra and cone sensitivity functions. A color is represented as a vector defined by the relative stimulation of the four cone types--ultraviolet, blue, green, and red. Color vectors are plotted in a tetrahedral, or quaternary, plot with the achromatic point at the origin and the ultraviolet/violet channel along the Z-axis. Each color vector is specified by the spherical coordinates theta, phi, and r. Hue is given by the angles theta and phi. Chroma is given by the magnitude of r, the distance from the achromatic origin. Color vectors of all distinct patches in a plumage characterize the plumage color phenotype. We describe the variation in color space occupancy of male bunting plumages, using various measures of color contrast, hue contrast and diversity, and chroma. Comparative phylogenetic analyses using linear parsimony (in MacClade) and generalized least squares (GLS) models (in CONTINUOUS) with a molecular phylogeny of the group document that plumage color evolution in the clade has been very dynamic. The single best-fit GLS evolutionary model of plumage color variation over the entire clade is a directional change model with no phylogenetic correlation among species. However, phylogenetic innovations in feather color production mechanisms--derived pheomelanin and carotenoid expression in two lineages--created new opportunities to colonize novel areas of color space and fostered the explosive differentiation in plumage color. Comparison of the tetrahedral color space of Goldsmith with that of Endler and Mielke demonstrates that both provide essentially identical results. Evolution of avian ultraviolet/violet opsin sensitivity in relation

  20. Priming Letters by Colors: Evidence for the Bidirectionality of Grapheme-Color Synesthesia

    ERIC Educational Resources Information Center

    Weiss, Peter H.; Kalckert, Andreas; Fink, Gereon R.

    2009-01-01

    In synesthesia, stimulation of one sensory modality leads to a percept in another nonstimulated modality, for example, graphemes trigger an additional color percept in grapheme-color synesthesia, which encompasses the variants letter-color and digit-color synesthesia. Until recently, it was assumed that synesthesia occurs strictly unidirectional:…

  1. True Colors of Mars

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image taken on Mars by the panoramic camera on the Mars Exploration Rover Spirit shows the rover's color calibration target, also known as the MarsDial. The target's mirror and the shadows cast on it by the Sun help scientists determine the degree to which dusty martian skies alter the panoramic camera's perception of color. By adjusting for this effect, Mars can be seen in all its true colors.

  2. An experimental method for the assessment of color simulation tools.

    PubMed

    Lillo, Julio; Alvaro, Leticia; Moreira, Humberto

    2014-07-22

    The Simulcheck method for evaluating the accuracy of color simulation tools in relation to dichromats is described and used to test three color simulation tools: Variantor, Coblis, and Vischeck. A total of 10 dichromats (five protanopes, five deuteranopes) and 10 normal trichromats participated in the current study. Simulcheck includes two psychophysical tasks: the Pseudoachromatic Stimuli Identification task and the Minimum Achromatic Contrast task. The Pseudoachromatic Stimuli Identification task allows determination of the two chromatic angles (h(uv) values) that generate a minimum response in the yellow–blue opponent mechanism and, consequently, pseudoachromatic stimuli (greens or reds). The Minimum Achromatic Contrast task requires the selection of the gray background that produces minimum contrast (near zero change in the achromatic mechanism) for each pseudoachromatic stimulus selected in the previous task (L(R) values). Results showed important differences in the colorimetric transformations performed by the three evaluated simulation tools and their accuracy levels. Vischeck simulation accurately implemented the algorithm of Brettel, Viénot, and Mollon (1997). Only Vischeck appeared accurate (similarity in huv and L(R) values between real and simulated dichromats) and, consequently, could render reliable color selections. It is concluded that Simulcheck is a consistent method because it provided an equivalent pattern of results for huv and L(R) values irrespective of the stimulus set used to evaluate a simulation tool. Simulcheck was also considered valid because real dichromats provided expected huv and LR values when performing the two psychophysical tasks included in this method.

  3. Broadband planar achromatic anomalous reflector based on dispersion engineering of spoof surface plasmon polariton

    NASA Astrophysics Data System (ADS)

    Yang, Jie; Wang, Jiafu; Li, Yongfeng; Wang, Zhuoluo; Chen, Hongya; Wang, Xinhua; Qu, Shaobo

    2016-11-01

    Planar reflectors are generally composed of non-uniform inclusions positioned on conducting sheet. Restricted by strong dispersion of the inclusions, the reflection of planar reflectors is usually chromatic. In this letter, we first obtain the dispersion relation for planar achromatic anomalous reflector (PAAR). Then, we propose to realize the dispersion relation based on dispersion engineering of spoof surface plasmon polariton (SSPP). Metallic blades structure is proposed to achieve the linear dispersion response by tailoring the weak dispersion region of SSPP. 6 metallic blade structures are designed to compose the super cell of the PAAR. A prototype was fabricated and measured. Both the simulation and experiment results show that the PAAR can achieve an achromatic reflected angle of 49.3° in 10.7-11.7 GHz under normal incidence.

  4. Alternate Lattice Design for Advanced Photon Source Multi-Bend Achromat Upgrade

    SciTech Connect

    Sun, Yipeng; Borland, Michael

    2015-01-01

    A 67-pm hybrid-seven-bend achromat (H7BA) lattice is proposed for a futureAdvanced Photon Source (APS)multibend- achromat (MBA) upgrade. This lattice requires use of a swap-out (on-axis) injection scheme. Alternate lattice design work has also been performed to achieve better beam dynamics performance than the nominal APS MBA lattice, in order to allow beam accumulation. One of such alternate H7BA lattice designs, which still targets a very low emittance of 76 pm, is discussed in this paper. With these lattices, existing APS injector complex can be employed without the requirement of a very high charge operation. Studies show that an emittance below 76 pm can be achieved with the employment of reverse bends in an alternate lattice. We discuss the predicted performance and requirements for these lattices and compare them to the nominal lattice.

  5. Design and modeling of a cost-effective achromatic Fresnel lens for concentrating photovoltaics.

    PubMed

    Vallerotto, Guido; Victoria, Marta; Askins, Stephen; Herrero, Rebeca; Domínguez, César; Antón, Ignacio; Sala, Gabriel

    2016-09-05

    This paper presents a novel Fresnel lens capable of significantly reducing chromatic aberration in solar applications. The optical performance of this achromatic lens has been analyzed through ray-tracing simulations, showing a concentration factor three times higher than that attained by a classic silicone on glass (SOG) Fresnel lens while maintaining the same acceptance angle. This should avoid the need for a secondary optical element, reducing the cost associated with its manufacturing and assembly and increasing the module reliability. The achromatic lens is made of inexpensive plastic and elastomer which allows a highly scalable and cost-competitive manufacturing process similar to the one currently used for the fabrication of SOG Fresnel lenses.

  6. Postscript: Qualitative and Quantitative Processes in the Perception of Achromatic Transparency

    ERIC Educational Resources Information Center

    Albert, Marc K.

    2008-01-01

    All of the data reported in Robilotto, Khang, and Zaidi (2002) Robilotto and Zaidi (2004), and Singh and Anderson (2002) are consistent with Robilotto and Zaidi's theory that perceived transparency (or opacity) is determined by the perceived contrast of the filter region. Kasrai and Kingdom's (2001) results also appear largely consistent with the…

  7. Color constancy in a scene with bright colors that do not have a fully natural surface appearance.

    PubMed

    Fukuda, Kazuho; Uchikawa, Keiji

    2014-04-01

    Theoretical and experimental approaches have proposed that color constancy involves a correction related to some average of stimulation over the scene, and some of the studies showed that the average gives greater weight to surrounding bright colors. However, in a natural scene, high-luminance elements do not necessarily carry information about the scene illuminant when the luminance is too high for it to appear as a natural object color. The question is how a surrounding color's appearance mode influences its contribution to the degree of color constancy. Here the stimuli were simple geometric patterns, and the luminance of surrounding colors was tested over the range beyond the luminosity threshold. Observers performed perceptual achromatic setting on the test patch in order to measure the degree of color constancy and evaluated the surrounding bright colors' appearance mode. Broadly, our results support the assumption that the visual system counts only the colors in the object-color appearance for color constancy. However, detailed analysis indicated that surrounding colors without a fully natural object-color appearance had some sort of influence on color constancy. Consideration of this contribution of unnatural object color might be important for precise modeling of human color constancy.

  8. Performance of an Achromatic Focal Plane Mask for Exoplanet Imaging Coronagraphy

    NASA Technical Reports Server (NTRS)

    Newman, Kevin; Belikov, Ruslan; Pluzhnik, Eugene; Balasubramanian, Kunjithapatham; Wilson, Dan

    2014-01-01

    Coronagraph technology combined with wavefront control is close to achieving the contrast and inner working angle requirements in the lab necessary to observe the faint signal of an Earth-like exoplanet in monochromatic light. An important remaining technological challenge is to achieve high contrast in broadband light. Coronagraph bandwidth is largely limited by chromaticity of the focal plane mask, which is responsible for blocking the stellar PSF. The size of a stellar PSF scales linearly with wavelength; ideally, the size of the focal plane mask would also scale with wavelength. A conventional hard-edge focal plane mask has a fixed size, normally sized for the longest wavelength in the observational band to avoid starlight leakage. The conventional mask is oversized for shorter wavelengths and blocks useful discovery space. Recently we presented a solution to the size chromaticity challenge with a focal plane mask designed to scale its effective size with wavelength. In this paper, we analyze performance of the achromatic size-scaling focal plane mask within a Phase Induced Amplitude Apodization (PIAA) coronagraph. We present results from wavefront control around the achromatic focal plane mask, and demonstrate the size-scaling effect of the mask with wavelength. The edge of the dark zone, and therefore the inner working angle of the coronagraph, scale with wavelength. The achromatic mask enables operation in a wider band of wavelengths compared with a conventional hard-edge occulter.

  9. Possibilities of achromatization of coaxial asymmetric phase shifters with an even number of reflections

    NASA Astrophysics Data System (ADS)

    Kovalev, V. I.; Ali, M.; Kovalev, S. V.; Kovalev, V. V.

    2014-07-01

    Two types of coaxial phase shifters (PSs) are considered. They are designed for spectral ellipsometry, where achromatism is improved using a pair of parallel Al mirrors oriented at small angle θ2 with respect to the incident laser beam. In a phase device based on a fused silica Fresnel rhomb, a high degree of achromatism (Δ = 440° ± 0.4° in the wavelength range of 250-1000 nm) is obtained with the aid of two Al mirrors coated by a native oxide layer about 5 nm thick and tilted at θ2 = 18°. The achromatism of four-mirror PSs can be improved using two mirrors with a thin dielectric coating (Al2O3 or MgF2) 20-80 nm thick, for which phase shift Δ is close to 180° at small angles θ2 and there are fragments of spectrum Δ(λ) where Δ decreases with an increase in the light wavelength.

  10. Approaches for Achieving Broadband Achromatic Phase Shifts for Visible Nulling Coronagraphy

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew R.; Lyon, Richard G.

    2012-01-01

    Visible nulling coronagraphy is one of the few approaches to the direct detection and characterization of Jovian and Terrestrial exoplanets that works with segmented aperture telescopes. Jovian and Terrestrial planets require at least 10(exp -9) and 10(exp -10) image plane contrasts, respectively, within the spectral bandpass and thus require a nearly achromatic pi-phase difference between the arms of the interferometer. An achromatic pi-phase shift can be achieved by several techniques, including sequential angled thick glass plates of varying dispersive materials, distributed thin-film multilayer coatings, and techniques that leverage the polarization-dependent phase shift of total-internal reflections. Herein we describe two such techniques: sequential thick glass plates and Fresnel rhomb prisms. A viable technique must achieve the achromatic phase shift while simultaneously minimizing the intensity difference, chromatic beam spread and polarization variation between each arm. In this paper we describe the above techniques and report on efforts to design, model, fabricate, align the trades associated with each technique that will lead to an implementations of the most promising one in Goddard's Visible Nulling Coronagraph (VNC).

  11. Memory Color Effect Induced by Familiarity of Brand Logos

    PubMed Central

    Kimura, Atsushi; Wada, Yuji; Masuda, Tomohiro; Goto, Sho-ichi; Tsuzuki, Daisuke; Hibino, Haruo; Cai, Dongsheng; Dan, Ippeita

    2013-01-01

    Background When people are asked to adjust the color of familiar objects such as fruits until they appear achromatic, the subjective gray points of the objects are shifted away from the physical gray points in a direction opposite to the memory color (memory color effect). It is still unclear whether the discrepancy between memorized and actual colors of objects is dependent on the familiarity of the objects. Here, we conducted two experiments in order to examine the relationship between the degree of a subject’s familiarity with objects and the degree of the memory color effect by using logographs of food and beverage companies. Methods and Findings In Experiment 1, we measured the memory color effects of logos which varied in terms of their familiarity (high, middle, or low). Results demonstrate that the memory color effect occurs only in the high-familiarity condition, but not in the middle- and low-familiarity conditions. Furthermore, there is a positive correlation between the memory color effect and the actual number of domestic stores of the brand. In Experiment 2, we assessed the semantic association between logos and food/beverage names by using a semantic priming task to elucidate whether the memory color effect of logos relates to consumer brand cognition, and found that the semantic associations between logos and food/beverage names in the high-familiarity brands were stronger than those in the low-familiarity brands only when the logos were colored correctly, but not when they were appropriately or inappropriately colored, or achromatic. Conclusion The current results provide behavioral evidence of the relationship between the familiarity of objects and the memory color effect and suggest that the memory color effect increases with the familiarity of objects, albeit not constantly. PMID:23874638

  12. Labels and Children's Perceptions of Faces

    ERIC Educational Resources Information Center

    Katz, Phyllis A.; Seavey, Carol

    1973-01-01

    The relation between type of label and perception of faces was assessed in second- and sixth-grade children. Labels associated with color increased color perception, whereas labels based on expressiveness increased differentiation of expression variations, but not color perception. (ST)

  13. How Does Color Work? divider pages only

    NASA Astrophysics Data System (ADS)

    Max, Maximum

    2002-06-01

    Modes of appearance and the physical circumstances which contribute to the perception of surface, volume, film, illumination and illuminant color ... how the eye/brain converts physical stimuli into experiences of color. -- Paul Green-Armytage

  14. General principles in motion vision: color blindness of object motion depends on pattern velocity in honeybee and goldfish.

    PubMed

    Stojcev, Maja; Radtke, Nils; D'Amaro, Daniele; Dyer, Adrian G; Neumeyer, Christa

    2011-07-01

    Visual systems can undergo striking adaptations to specific visual environments during evolution, but they can also be very "conservative." This seems to be the case in motion vision, which is surprisingly similar in species as distant as honeybee and goldfish. In both visual systems, motion vision measured with the optomotor response is color blind and mediated by one photoreceptor type only. Here, we ask whether this is also the case if the moving stimulus is restricted to a small part of the visual field, and test what influence velocity may have on chromatic motion perception. Honeybees were trained to discriminate between clockwise- and counterclockwise-rotating sector disks. Six types of disk stimuli differing in green receptor contrast were tested using three different rotational velocities. When green receptor contrast was at a minimum, bees were able to discriminate rotation directions with all colored disks at slow velocities of 6 and 12 Hz contrast frequency but not with a relatively high velocity of 24 Hz. In the goldfish experiment, the animals were trained to detect a moving red or blue disk presented in a green surround. Discrimination ability between this stimulus and a homogenous green background was poor when the M-cone type was not or only slightly modulated considering high stimulus velocity (7 cm/s). However, discrimination was improved with slower stimulus velocities (4 and 2 cm/s). These behavioral results indicate that there is potentially an object motion system in both honeybee and goldfish, which is able to incorporate color information at relatively low velocities but is color blind with higher speed. We thus propose that both honeybees and goldfish have multiple subsystems of object motion, which include achromatic as well as chromatic processing.

  15. Background matching by means of dorsal color change in treefrog populations (Hyla japonica).

    PubMed

    Choi, Noori; Jang, Yikweon

    2014-02-01

    Treefrogs change dorsal coloration to match background colors, presumably for predator avoidance. Dorsal coloration in treefrogs results from rearrangement of pigment granules in dermal chromatophores. This physiological basis for color change suggests that brightness and chroma are the color components that may change in response to background color. However, results of experiments are conflicting in that there is no consensus as to which color component is critical for color change in treefrogs. We tested predictions of the physiological model for color change in treefrogs by investigating dorsal color change under five background colors in three different populations of the treefrog Hyla japonica. Differences in color components between background colors and frogs were used as a measure of background matching. Throughout a 1-week experimental period, brightness and chroma differences decreased monotonically, while hue difference remained constant for all background colors. Chroma differences were smaller with the natural colors such as green and brown than with achromatic colors. Moreover, variation in color change among frogs from three localities that differed in land cover suggested that chroma change capacity may be sensitive to environmental conditions. Under the white background color, however, decreasing brightness difference seemed to be crucial to background matching. Furthermore, chroma difference and brightness difference did not decrease indefinitely, suggesting a trade-off between chroma difference and brightness difference under the white background. Thus, background matching may generally occur by decreasing chroma difference under most background colors in H. japonica, but brightness matching may be important under the white color.

  16. Color constancy in Japanese animation

    NASA Astrophysics Data System (ADS)

    Ichihara, Yasuyo G.

    2006-01-01

    In this study, we measure the colors used in a Japanese Animations. The result can be seen on CIE-xy color spaces. It clearly shows that the color system is not a natural appearance system but an imagined and artistic appearance system. Color constancy of human vision can tell the difference in skin and hair colors between under moonlight and day light. Human brain generates a match to the memorized color of an object from daylight viewing conditions to the color of the object in different viewing conditions. For example, Japanese people always perceive the color of the Rising Sun in the Japanese flag as red even in a different viewing condition such as under moonlight. Color images captured by a camera cannot present those human perceptions. However, Japanese colorists in Animation succeeded in painting the effects of color constancy not only under moonlight but also added the memory matching colors. They aim to create a greater impact on viewer's perceptions by using the effect of the memory matching colors. In this paper, we propose the Imagined Japanese Animation Color System. This system in art is currently a subject of research in Japan. Its importance is that it could also provide an explanation on how human brain perceives the same color under different viewing conditions.

  17. Multiple neural mechanisms for coloring words in synesthesia.

    PubMed

    Yokoyama, Takemasa; Noguchi, Yasuki; Koga, Hiroki; Tachibana, Ryosuke; Saiki, Jun; Kakigi, Ryusuke; Kita, Shinichi

    2014-07-01

    Grapheme-color synesthesia is a phenomenon in which achromatic letters/digits automatically induce particular colors. When multiple letters are integrated into a word, some synesthetes perceive that all those letters are changed into the same color, reporting lexical color to that word. Previous psychological studies found several "rules" that determine those lexical colors. The colors to most words are determined by the first letters of the words, while some words in ordinal sequences have their specific colors. Recent studies further reported the third case where lexical colors might be influenced by semantic information of words. Although neural mechanisms determining those lexical colors remained unknown, here we identified three separate neural systems in the synesthete's brain underlying three rules for illusory coloring of words. In addition to the occipito-temporal and parietal regions previously found to be associated with the grapheme-color synesthesia, neural systems for lexical coloring extended to linguistic areas in the left inferior frontal and anterior temporal regions that were engaged in semantic analyses of words. Those results indicate an involvement of wider and higher neural networks than previously assumed in a production of synesthetic colors to visual stimuli and further showed a multiplicity of synesthetic mechanisms represented in the single brain.

  18. EEG alpha rhythms and transient chromatic and achromatic pattern visual evoked potentials in children and adults.

    PubMed

    Boon, Mei Ying; Chan, Kar Ying; Chiang, Jaclyn; Milston, Rebecca; Suttle, Catherine

    2011-04-01

    Transient chromatic pattern visual evoked potentials (VEPs) have been found to be less repeatable in morphology in children than in adults at low to moderate chromatic contrasts. The purpose of this study is to investigate whether low repeatability of VEP components can be associated with high alpha power, in a comparison of alpha activity in children and adults. Transient chromatic contrast and achromatic resolution VEPs were recorded in children (n = 14, mean 9.6 years) and adults (n = 12, mean 21.8 years) with normal vision and assessed for repeatability. Isoluminant chromatic (magenta-cyan) and luminance-modulated achromatic grating stimuli were presented at and above psychophysical threshold levels, in pattern onset-offset at 2 Hz temporal frequency. EEGs (eyes closed and open) were recorded as single sweeps (1 s long) over three 30 s periods while facing a uniform computer display. An index of VEP detectability by observation was developed based on VEP component repeatability. The index was examined for correlations with alpha-wave parameters. Alpha power was calculated as the sum of the powers of 8-13 Hz frequencies of the EEG sweeps (using the discrete Fourier transform). Alpha power variability was calculated using the standard deviation of the powers of each sweep in a 30 s time period. The children had significantly higher alpha powers than the adults for both the eyes-open and eyes-closed conditions. Alpha power variability was significantly higher for the eyes-open condition only. There was no relationship between alpha power parameters and index of VEP detectability by observation for both the chromatic and achromatic grating stimuli. Poor repeatability of transient pattern VEPs is not associated with high alpha power or its variability in EEG measurements in older children or young adults at Oz.

  19. The role of color in motion feature-binding errors

    PubMed Central

    Stepien, Natalie N.; Shevell, Steven K.

    2015-01-01

    Color-motion feature-binding errors occur in the periphery when half of the objects are red and move downward, and the other half are green and move upward. When red and green objects in the central visual field are similar but move in the opposite directions (red upward, green downward), peripheral objects often take on the perceived motion direction of the like-colored central objects (Wu, Kanai, & Shimojo, 2004). The present study determined whether color is essential to elicit these motion-binding errors, and tested two hypotheses that attempt to explain them. One hypothesis holds that binding errors occur because peripheral and central objects become linked if they have combinations of features in common. A peripheral object's link to central objects overwhelms its posited weak peripheral representation for motion feature binding, so the peripheral object appears to move in the direction of the linked central objects. Eliminating color by making all stimuli achromatic, therefore, should not increase peripheral binding errors. An alternative hypothesis is that binding errors depend on the overall feature correspondence among central and peripheral features represented at a preconjunctive level. In this case, binding errors may increase when all objects are changed to achromatic because chromatic central/peripheral correspondence is maximal (100%). Experiments showed more motion-binding errors with all-achromatic objects than with half red and half green objects. This and additional findings imply that peripheral motion-binding errors (a) can be elicited without color and (b) depend at least in part on the similarity of central and peripheral features represented preconjunctively. PMID:26381839

  20. Optimization of color LC displays

    NASA Astrophysics Data System (ADS)

    Kosmowski, Bogdan B.

    1995-08-01

    The advancement of the liquid crystal display (LCD) technology, and improvements of the optical and electro-optical properties, have enabled the broad expansion of LCDs application field. The rapid development of the multimedia techniques, new applications in automotive, office, medical domain, forced the demand for the color displays--for the information presentation with the color code. The necessity to fulfil many contradictory and extreme conditions caused the development of the optimization procedures of the color LC displays to be a big problem. Most of the LCDs used nowadays are the twisted nematic, super twisted nematic, and active matrix thin film transistor LCD. The characterization of the achromatic black/white LCDs is made by means of photometric measuring methods, and quantitative measures are used: luminance, reflectance, contrast, contrast ration; as a function of a driving voltage, viewing angle, temperature, etc. The characterization of the color LCD is based on the spectral distributions of the transmittance or reflectance. Quantitative measures are chromatic coordinates and luminance factors are defined according to the colorimetric systems--CIE 1931, CIE 1976, CIELUV, CIELAB. The color difference (Delta) E in the CIELUV system is applied as a optimization parameter for the color display module. The spectral properties of all optical elements of the display module are analyzed and their influence on the set of the optical factors of LCD is evaluated. The correlation between technological parameters and optical characteristics of the LCD has been investigated. The choice of the optimization criterion is discussed and the optimization algorithm is proposed. Results of the color displays evaluation for some examples with different preconditions are presented.

  1. Modified Savart polariscope with wide field of view and achromatic lateral displacement

    NASA Astrophysics Data System (ADS)

    Quan, Naicheng; Zhang, Chunmin; Mu, Tingkui

    2017-01-01

    A modified Savart polariscope with wide field of view and achromatic lateral displacement is presented. The modified Savart polariscope can be made from two different birefringent crystal materials. The principle of the element is described and the impacts of systematic errors are analyzed. The achievement and performance of the modified Savart polariscope is demonstrated with numerical simulations. The maximum acceptable angle of incidence can be increased by an order of magnitude and the chromatic variations in lateral displacement are inhibited obviously across the specified spectral range 0.4 μm to 0.9 μm.

  2. Super-achromatic microprobe for ultrahigh-resolution endoscopic OCT imaging at 800 nm (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yuan, Wu; Alemohammad, Milad; Yu, Xiaoyun; Yu, Shaoyong; Li, Xingde

    2016-03-01

    In this paper, we report a super-achromatic microprobe made with fiber-optic ball lens to enable ultrahigh-resolution endoscopic OCT imaging. An axial resolution of ~2.4 µm (in air) can be achieved with a 7-fs Ti:Sapphire laser. The microprobe has minimal astigmatism which affords a high transverse resolution of ~5.6 µm. The miniaturized microprobe has an outer diameter of ~520 µm including the encasing metal guard and can be used to image small luminal organs. The performance of the ultrahigh-resolution OCT microprobe was demonstrated by imaging rat esophagus, guinea pig esophagus, and mouse rectum in vivo.

  3. Design, manufacturing, performance and application of wide angle aspherical achromatic doublet

    NASA Astrophysics Data System (ADS)

    Melich, Radek; Procháska, František; Tomka, David; Rail, Zdeněk.; Bartoňíček, Jiří; Pleštil, Jan; Šrajer, Bohdan

    2016-11-01

    The paper describes an achromatic Steinhal type doublet that employs an aspherical surface to allow wide angle imaging. A design criteria, optimization techniques and tolerancing of the doublet are described. Further a manufacturing process of the system and achieved optical performance measurement is discussed. Benefits of the wide angle imaging doublet are recently planned to be used in automotive industry application, namely for optimizing of head-light performance and their final evaluation. The final device is planned to be part of the production line.

  4. Development of achromatic full-field hard x-ray microscopy with two monolithic imaging mirrors

    NASA Astrophysics Data System (ADS)

    Matsuyama, S.; Kino, H.; Yasuda, S.; Kohmura, Y.; Okada, H.; Ishikawa, T.; Yamauchi, K.

    2015-09-01

    Advanced Kirkpatrick-Baez mirror optics using two monolithic imaging mirrors was developed to realize an achromatic, high-resolution, and a high-stability full-field X-ray microscope. The mirror consists of an elliptical section and a hyperbolic section on a quartz glass substrate, in which the geometry follows the Wolter (type I) optics rules. A preliminary test was performed at SPring-8 using X-rays monochromatized to 9.881 keV. A 100-nm feature on a Siemens star chart could be clearly observed.

  5. Apparatus and methods for using achromatic phase matching at high orders of dispersion

    DOEpatents

    Richman, Bruce; Trebino, Rick; Bisson, Scott; Sidick, Erkin

    2001-01-01

    Achromatic phase-matching (APM) is used for efficiently multiplying the frequency of broad bandwidth light by using a nonlinear optical medium comprising a second-harmonic generation (SHG) crystal. Stationary optical elements whose configuration, properties, and arrangement have been optimized to match the dispersion characteristics of the SHG crystal to at least the second order. These elements include a plurality of prismatic elements for directing an input light beam onto the SHG crystal such that each ray wavelength is aligned to match the phase-matching angle for the crystal at each wavelength of light to at least the second order and such that every ray wavelength overlap within the crystal.

  6. Magnifying Lenses with Weak Achromatic Bends for High-Energy Electron Radiography

    SciTech Connect

    Walstrom, Peter Lowell

    2015-02-27

    This memo briefly describes bremsstrahlung background effects in GeV-range electron radiography systems and the use of weak bending magnets to deflect the image to the side of the forward bremsstrahlung spot to reduce background. The image deflection introduces first-order chromatic image blur due to dispersion. Two approaches to eliminating the dispersion effect to first order by use of magnifying lens with achromatic bends are described. Also, higher-order image blur terms caused by weak bends are also discussed, and shown to be negligibly small in most cases of interest.

  7. Demonstration of achromatic cold-neutron microscope utilizing axisymmetric focusing mirrors

    SciTech Connect

    Liu, D.; Khaykovich, B.; Hussey, D.; Jacobson, D.; Arif, M.; Gubarev, M. V.; Ramsey, B. D.; Moncton, D. E.

    2013-05-06

    An achromatic cold-neutron microscope with magnification 4 is demonstrated. The image-forming optics is composed of nested coaxial mirrors of full figures of revolution, so-called Wolter optics. The spatial resolution, field of view, and depth of focus are measured and found consistent with ray-tracing simulations. Methods of increasing the resolution and magnification are discussed, as well as the scientific case for the neutron microscope. In contrast to traditional pinhole-camera neutron imaging, the resolution of the microscope is determined by the mirrors rather than by the collimation of the beam, leading to possible dramatic improvements in the signal rate and resolution.

  8. Color planner for designers based on color emotions

    NASA Astrophysics Data System (ADS)

    Cheng, Ka-Man; Xin, John H.; Taylor, Gail

    2002-06-01

    During the color perception process, an associated feeling or emotion is induced in our brains, and this kind of emotion is termed as 'color emotion.' The researchers in the field of color emotions have put many efforts in quantifying color emotions with the standard color specifications and evaluating the influence of hue, lightness and chroma to the color emotions of human beings. In this study, a color planner was derived according to these findings so that the correlation of color emotions and standard color specifications was clearly indicated. Since people of different nationalities usually have different color emotions as different cultural and traditional backgrounds, the subjects in this study were all native Hong Kong Chinese and the color emotion words were all written in Chinese language in the visual assessments. Through the color planner, the designers from different areas, no matter fashion, graphic, interior or web site etc., can select suitable colors for inducing target color emotions to the customers or product-users since different colors convey different meanings to them. In addition, the designers can enhance the functionality and increase the attractiveness of their designed products by selecting suitable colors.

  9. Is "Σ" purple or green? Bistable grapheme-color synesthesia induced by ambiguous characters.

    PubMed

    Kim, Suhkyung; Blake, Randolph; Kim, Chai-Youn

    2013-09-01

    People with grapheme-color synesthesia perceive specific colors when viewing different letters or numbers. Previous studies have suggested that synesthetic color experience can be bistable when induced by an ambiguous character. However, the exact relationship between processes underlying the identity of an alphanumeric character and the experience of the induced synesthetic color has not been examined. In the present study, we explored this by focusing on the temporal relation of inducer identification and color emergence using inducers whose identity could be rendered ambiguous upon rotation of the characters. Specifically, achromatic alphabetic letters (W/M) and digits (6/9) were presented at varying angles to 9 grapheme-color synesthetes. Results showed that grapheme identification and synesthetically perceived grapheme color covary with the orientation of the test stimulus and that synesthetes were slower naming the experienced color than identifying the character, particularly at intermediate angles where ambiguity was greatest.

  10. Achromatic and high-resolution full-field X-ray microscopy based on total-reflection mirrors.

    PubMed

    Matsuyama, Satoshi; Emi, Yoji; Kino, Hidetoshi; Kohmura, Yoshiki; Yabashi, Makina; Ishikawa, Tetsuya; Yamauchi, Kazuto

    2015-04-20

    We developed an achromatic and high-resolution full-field X-ray microscope based on advanced Kirkpatrick-Baez mirror optics that comprises two pairs of elliptical mirrors and hyperbolic mirrors utilizing the total reflection of X-rays. Performance tests to investigate the spatial resolution and chromatic aberration were performed at SPring-8. The microscope clearly resolved the pattern with ~100-nm feature size. Imaging the pattern by changing the X-ray energy revealed achromatism in the wide energy range of 8-11 keV.

  11. Coherence holography by achromatic 3-D field correlation of generic thermal light with an imaging Sagnac shearing interferometer.

    PubMed

    Naik, Dinesh N; Ezawa, Takahiro; Singh, Rakesh Kumar; Miyamoto, Yoko; Takeda, Mitsuo

    2012-08-27

    We propose a new technique for achromatic 3-D field correlation that makes use of the characteristics of both axial and lateral magnifications of imaging through a common-path Sagnac shearing interferometer. With this technique, we experimentally demonstrate, for the first time to our knowledge, 3-D image reconstruction of coherence holography with generic thermal light. By virtue of the achromatic axial shearing implemented by the difference in axial magnifications in imaging, the technique enables coherence holography to reconstruct a 3-D object with an axial depth beyond the short coherence length of the thermal light.

  12. 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 ...

  13. The nature of colors

    NASA Astrophysics Data System (ADS)

    da Pos, Osvaldo

    2002-06-01

    Color is a visible aspect of objects and lights, and as such is an objective characteristic of our phenomenal world. Correspondingly also objects and lights are objective, although their subjectivity cannot be disregarded since they belong to our phenomenal world. The distinction between perception and sensation deals with colors seen either in complex displays or in isolation. Reality of colors is apparently challenged by virtual reality, while virtual reality is a good example of what colors are. It seems difficult to combine that aspect of reality colors have in our experience and the concept that colors represent something in the external environment: the distinction between stimulation and perceived object is crucial for understanding the relationships between phenomenal world and physical reality. A modern concept of isomorphism seems useful in interpreting the role of colors. The relationship between the psychological structure of colors and the physical stimulation is enlightened by the analysis of pseudocolors. The perceptual, subjective characteristics of colors go along with the subjectivity of scientific concepts. Colors, emotions, and concepts are all in some people's mind: none of them is independent of the subject mind. Nevertheless they can be communicated from person to person by an appropriate scientific terminology.

  14. Proximate bases of silver color in anhinga (Anhinga anhinga) feathers.

    PubMed

    Shawkey, Matthew D; Maia, Rafael; D'Alba, Liliana

    2011-11-01

    Colors of living organisms are produced by selective light absorption from pigments and/or by light scattering from highly ordered nanostructures (i.e., structural color). While the physical bases of metallic colors of arthropods and fish are fairly well-known, those of birds are not. Here we examine structurally based silver color and its production in feathers of the waterbird species Anhinga. This achromatic color is distinguished from grey by high specular reflectance, from white by low diffuse reflectance, and from both by high gloss. Light and electron microscopy revealed three modifications of feathers likely leading to silver color. First, proximal barbules were highly elongated and contained glossy black color at their base and white color at their pennulum. Second, this glossy black portion contained a single outer layer of keratin weakly bounded by melanosomes. Finally, the white portion contained a disordered amorphous matrix of keratin and air. Optical analyzes suggest that these structures produce, respectively, glossy black color through thin-film interference and white color through incoherent light scattering. Silver color likely results from the combined reflectance of these adjacent structures. This represents a distinct mechanism for attaining silver colors that may have been partially derived through selection for display, thermoregulation or decreased hydrophobicity.

  15. Saccadic suppression of achromatic and chromatic responses measured by increment-threshold spectral sensitivity

    NASA Astrophysics Data System (ADS)

    Uchikawa, Keiji; Sato, Masayuki

    1995-04-01

    We measured spectral-sensitivity functions during saccadic eye movement by the increment-threshold method to test whether saccades selectively suppressed achromatic or chromatic responses. A circular monochromatic test stimulus of 12-deg diameter was presented for 10 ms on a 62 deg X 43 deg white background, and observations were made 6-deg saccades, and immediately after saccades. In two additional conditions the test stimulus was made to move during fixation and during 6-deg saccades at the same speed and in the same direction as the saccades. The during-fixation spectral-sensitivity function was found to resemble the relative luminous efficiency V( lambda ) function in shape except for the case of short wavelengths, whereas the during-saccade spectral-sensitivity function showed lower sensitivity for all wavelengths and had three prominent peaks at approximately 440, 530, and 600 nm. These characteristics did not depend on whether the stimulus was stationary or moving. These results indicated that saccadic suppression was greater for achromatic than for chromatic response. A possible suppression mechanism was discussed involving the magno and parvo pathways.

  16. Conceptual Design of Front Ends for the Advanced Photon Source Multi-bend Achromats Upgrade

    SciTech Connect

    Jaski, Y.; Westferro, F.; Lee, S. H.; Yang, B.; Abliz, M.; Ramanathan, M.

    2016-07-27

    The proposed Advanced Photon Source (APS) upgrade from a double-bend achromats (DBA) to multi-bend achromats (MBA) lattice with ring energy change from 7 GeV to 6 GeV and beam current from 100 mA to 200 mA poses new challenges for front ends. All front ends must be upgraded to fulfill the following requirements: 1) handle the high heat load from two insertion devices in either inline or canted configuration, 2) include a clearing magnet in the front end to deflect and dump any electrons in case the electrons escape from the storage ring during swap-out injection with the safety shutters open, 3) incorporate the next generation x-ray beam position monitors (XBPMs) into the front end to meet the new stringent beam stability requirements. This paper presents the evaluation of the existing APS front ends and standardizes the insertion device (ID) front ends into two types: one for the single beam and one for the canted beams. The conceptual design of high heat load front end (HHLFE) and canted undulator front end (CUFE) for APS MBA upgrade is presented.

  17. Suppression of the emittance growth induced by coherent synchrotron radiation in triple-bend achromats

    NASA Astrophysics Data System (ADS)

    Huang, Xi-Yang; Jiao, Yi; Xu, Gang; Cui, Xiao-Hao

    2015-05-01

    The coherent synchrotron radiation (CSR) effect in a bending path plays an important role in transverse emittance dilution in high-brightness light sources and linear colliders, where the electron beams are of short bunch length and high peak current. Suppression of the emittance growth induced by CSR is critical to preserve the beam quality and help improve the machine performance. It has been shown that the CSR effect in a double-bend achromat (DBA) can be analyzed with the two-dimensional point-kick analysis method. In this paper, this method is applied to analyze the CSR effect in a triple-bend achromat (TBA) with symmetric layout, which is commonly used in the optics designs of energy recovery linacs (ERLs). A condition of cancelling the CSR linear effect in such a TBA is obtained, and is verified through numerical simulations. It is demonstrated that emittance preservation can be achieved with this condition, and to a large extent, has a high tolerance to the fluctuation of the initial transverse phase space distribution of the beam. Supported by National Natural Science Foundation of China (11475202, 11405187) and Youth Innovation Promotion Association of Chinese Academy of Sciences (2015009)

  18. Influence of residual achromatic aberration on the isochronicity in the FAIR collector ring

    NASA Astrophysics Data System (ADS)

    Litvinov, S.; Dolinskii, A.; Koop, I.; Weick, H.

    2015-11-01

    In order to understand how the heavy elements from iron to uranium were produced in nature, masses and lifetimes of extremely exotic nuclei up to the limits of nuclear existence have to be measured. In particular, for modeling the r-process nucleosynthesis the nuclei close to the neutron drip line are relevant. However, such nuclei typically have very short half-lives and furthermore have tiny production cross-sections. The Super-FRS-CR facility at FAIR [1] offers unique possibilities for such measurements. Exotic nuclei with half-lives of {{{T}}}1/2\\gt 20 μ {{s}} will be produced and selected in flight with the Super-FRS fragment separator [2], injected and stored in the large acceptance collector ring (CR) [3] which will be tuned into the isochronous ion-optical mode and operated as a time-of-flight (TOF) spectrometer. We demonstrate here, a comparison between the achromatic and non-achromatic isochronous optics. The importance of the TOF detectors installation in the dispersion free region will be shown.

  19. Color visualization of cyclic magnitudes

    NASA Astrophysics Data System (ADS)

    Restrepo, Alfredo; Estupiñán, Viviana

    2014-02-01

    We exploit the perceptual, circular ordering of the hues in a technique for the visualization of cyclic variables. The hue is thus meaningfully used for the indication of variables such as the azimuth and the units of the measurement of time. The cyclic (or circular) variables may be both of the continuous type or the discrete type; among the first there is azimuth and among the last you find the musical notes and the days of the week. A correspondence between the values of a cyclic variable and the chromatic hues, where the natural circular ordering of the variable is respected, is called a color code for the variable. We base such a choice of hues on an assignment of of the unique hues red, yellow, green and blue, or one of the 8 even permutations of this ordered list, to 4 cardinal values of the cyclic variable, suitably ordered; color codes based on only 3 cardinal points are also possible. Color codes, being intuitive, are easy to remember. A possible low accuracy when reading instruments that use this technique is compensated by fast, ludic and intuitive readings; also, the use of a referential frame makes readings precise. An achromatic version of the technique, that can be used by dichromatic people, is proposed.

  20. Chromatic settings and the structural color constancy index.

    PubMed

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

    2013-03-11

    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.

  1. The Chemistry of Color Photography

    ERIC Educational Resources Information Center

    Guida, Wayne C.; Raber, Douglas J.

    1975-01-01

    Presents several topics in color photography which can serve as an introduction of scientific concepts into the classroom, such as: photochemistry (energy transport), organic chemistry (dye formation), physics (nature of light), psychology (color perception), and engineering (isolation of different chemical processes within layers of the film).…

  2. Social perception in synaesthesia for colour.

    PubMed

    Janik McErlean, Agnieszka B; Susilo, Tirta; Rezlescu, Constantin; Bray, Amy; Banissy, Michael J

    2016-12-11

    Synaesthesia is a rare phenomenon in which stimulation in one modality (e.g., audition) evokes a secondary percept not associated with the first (e.g., colour). Prior work has suggested links between synaesthesia and other neurodevelopmental conditions that are linked to altered social perception abilities. With this in mind, here we sought to examine social perception abilities in grapheme-colour synaesthesia (where achromatic graphemes evoke colour experiences) by examining facial identity and facial emotion perception in synaesthetes and controls. Our results indicate that individuals who experience grapheme-colour synaesthesia outperformed controls on tasks involving fine visual discrimination of facial identity and emotion, but not on tasks involving holistic face processing. These findings are discussed in the context of broader perceptual and cognitive traits previously associated with synaesthesia for colour, with the suggestion that performance benefits shown by grapheme-colour synaesthetes may be related to domain-general visual discrimination biases observed in this group.

  3. Color vision, cones, and color-coding in the cortex.

    PubMed

    Conway, Bevil R

    2009-06-01

    Color processing begins with the absorption of light by cone photoreceptors, and progresses through a series of hierarchical stages: Retinal signals carrying color information are transmitted through the lateral geniculate nucleus of the thalamus (LGN) up to the primary visual cortex (V1). From V1, the signals are processed by the second visual area (V2); then by cells located in subcompartments ("globs") within the posterior inferior temporal (PIT) cortex, a brain region that encompasses area V4 and brain regions immediately anterior to V4. Color signals are then processed by regions deep within the inferior temporal (IT) cortex including area TE. As a heuristic, one can consider each of these stages to be involved in constructing a distinct aspect of the color percept. The three cone types are the basis for trichromacy; retinal ganglion cells that respond in an opponent fashion to activation of different cone classes are the basis for color opponency (these "cone-opponent" cells increase their firing rate above baseline to activation of one cone class and decrease their firing rate below baseline to activation of a different cone class); double-opponent neurons in the V1 generate local color contrast and are the building blocks for color constancy; glob cells elaborate the perception of hue; and IT integrates color perception in the context of behavior. Finally, though nothing is known, these signals presumably interface with motor programs and emotional centers of the brain to mediate the widely acknowledged emotional salience of color.

  4. Procedures for Testing Color Vision,

    DTIC Science & Technology

    1981-01-01

    for the report were chosen for their special competences and with regard for appropriate balance. This report has been reviewed by a group other than...determine quantitatively whether the color-defective applicant was competent to make the color perception requirements of a particular job. The colors...reconnaissance des anomalies de la vision des couleurs. Archives des Maladies Professionnelles , de M6decine du Tray et de S~curit6 Sociale (Paris) 29:293-314

  5. Fabrication of Achromatic Infrared Wave Plate by Direct Imprinting Process on Chalcogenide Glass

    NASA Astrophysics Data System (ADS)

    Yamada, Itsunari; Yamashita, Naoto; Tani, Kunihiko; Einishi, Toshihiko; Saito, Mitsunori; Fukumi, Kouhei; Nishii, Junji

    2012-07-01

    An achromatic infrared wave plate was fabricated by forming a subwavelength grating on the chalcogenide glass using direct imprint lithography. A low toxic chalcogenide glass (Sb-Ge-Sn-S system) substrate was imprinted with a grating of 1.63-µm depth, a fill factor of 0.7, and 3-µm period using glassy carbon as a mold at 253 °C and 3.8 MPa. Phase retardation of the element reached around 30° at 8.5-10.5 µm wavelengths, and the transmittance exceeded that of a flat substrate over 8 µm wavelength. Fabrication of the mid-infrared wave plate is thereby less expensive than that of conventional crystalline wave plates.

  6. The achromatic design of an atmospheric dispersion corrector for extremely large telescopes.

    PubMed

    Bahrami, Mehdi; Goncharov, Alexander V

    2011-08-29

    For off-zenith observations with ground-based astronomical telescopes, the effect of atmospheric dispersion relative to diffraction on image size increases with telescope diameter. Correction of atmospheric dispersion in extremely large telescopes (ELTs) might become critical. A common solution for ELTs is to use linear atmospheric dispersion correctors (ADCs). In spite of their simplicity, the intrinsic chromatic aberrations of linear ADCs could render diffraction-limited imaging impossible when used in a fast focus. The chromatic problems of the linear ADC in ELTs can be resolved by replacing the linear ADC by the achromatic ADC designs presented here, which provide diffraction-limited image quality and offer several opto-mechanical advantages over linear ADCs.

  7. Metal-mesh achromatic half-wave plate for use at submillimeter wavelengths.

    PubMed

    Pisano, Giampaolo; Savini, Giorgio; Ade, Peter A R; Haynes, Vic

    2008-11-20

    A metal-mesh achromatic half-wave plate (HWP) has been designed, manufactured, and tested for potential use in millimeter and submillimeter astronomical instruments. The prototype device presented here is based on a 12-grid Shatrow [IEEE Trans. Antennas Propag. 43, 109 (1995)] recipe to operate over the frequency range of 120-180 GHz. Transmission line modeling and finite-element analysis [Ansoft HFSS website: http://www.ansoft.com/hfss/] were used to optimize the design geometrical parameters in terms of the device transmission, reflection, absorption, phase-shift, and cross-polarization as a function of frequency. The resulting prototype device was constructed and characterized using incoherent radiation from a polarizing Fourier transform spectrometer to explore its frequency and polarization behavior. These measurements are shown to be in excellent agreement with the models. Lists of the achieved HWP performance characteristics are reported.

  8. A case study of cortical colour "blindness" with relatively intact achromatic discrimination.

    PubMed

    Heywood, C A; Wilson, B; Cowey, A

    1987-01-01

    A patient is described whose most striking visual disorder was a grossly impaired ability to discriminate between different colours (hues) that were matched for brightness. In contrast his ability to discriminate between different neutral greys presented in the same fashion was much less abnormal, even though the greys were perceptually difficult. Although visual acuity was reduced and visual fields were constricted, and the patient's memory was moderately impaired, these associated symptoms could not themselves be the cause of his unusual colour vision. The patient had the symptoms of cerebral achromatopsia, and the relative preservation of his form vision (when his reduced acuity is taken into account) and his achromatic vision supports the view that the many different visual cortical areas recently demonstrated in the brains of monkeys, and presumed to exist in man, have a perceptual specialisation that matches their physiological differences.

  9. Two-stage reflective optical system for achromatic 10 nm x-ray focusing

    NASA Astrophysics Data System (ADS)

    Motoyama, Hiroto; Mimura, Hidekazu

    2015-12-01

    Recently, coherent x-ray sources have promoted developments of optical systems for focusing, imaging, and interferometers. In this paper, we propose a two-stage focusing optical system with the goal of achromatically focusing pulses from an x-ray free-electron laser (XFEL), with a focal width of 10 nm. In this optical system, the x-ray beam is expanded by a grazing-incidence aspheric mirror, and it is focused by a mirror that is shaped as a solid of revolution. We describe the design procedure and discuss the theoretical focusing performance. In theory, soft-XFEL lights can be focused to a 10 nm area without chromatic aberration and with high reflectivity; this creates an unprecedented power density of 1020 W cm-2 in the soft-x-ray range.

  10. Achromatic Metalens over 60 nm Bandwidth in the Visible and Metalens with Reverse Chromatic Dispersion.

    PubMed

    Khorasaninejad, M; Shi, Z; Zhu, A Y; Chen, W T; Sanjeev, V; Zaidi, A; Capasso, F

    2017-03-08

    In this Letter, we experimentally report an achromatic metalens (AML) operating over a continuous bandwidth in the visible. This is accomplished via dispersion engineering of dielectric phase shifters: titanium dioxide nanopillars tiled on a dielectric spacer layer above a metallic mirror. The AML works in reflection mode with a focal length independent of wavelength from λ = 490 to 550 nm. We also design a metalens with reverse chromatic dispersion, where the focal length increases as the wavelength increases, contrary to conventional diffractive lenses. The ability to engineer the chromatic dispersion of metalenses at will enables a wide variety of applications that were not previously possible. In particular, for the AML design, we envision applications such as imaging under LED illumination, fluorescence, and photoluminescence spectroscopy.

  11. Achromatic flat optical components via compensation between structure and material dispersions

    PubMed Central

    Li, Yang; Li, Xiong; Pu, Mingbo; Zhao, Zeyu; Ma, Xiaoliang; Wang, Yanqin; Luo, Xiangang

    2016-01-01

    Chromatism causes great quality degradation of the imaging system, especially for diffraction imaging. The most commonly method to overcome chromatism is refractive/diffractive hybrid optical system which, however, sacrifices the light weight and integration property of diffraction elements. A method through compensation between the structure dispersion and material dispersion is proposed to overcome the chromatism in flat integrated optical components. This method is demonstrated by making use of silver nano-slits waveguides to supply structure dispersion of surface plasmon polaritons (SPP) in metal-insulator-metal (MIM) waveguide to compensate the material dispersion of metal. A broadband deflector and lens are designed to prove the achromatic property of this method. The method demonstrated here may serve as a solution of broadband light manipulation in flat integrated optical systems. PMID:26794855

  12. MAGNET DESIGNS FOR THE MULTI-BEND ACHROMAT LATTICE AT THE ADVANCED PHOTON SOURCE

    SciTech Connect

    Jaski, M.; Liu, J.; Jain, A.; Spataro, C; Harding, D. J.; Kashikhin, V.; Lopes, M. L.

    2015-01-01

    The Advanced Photon Source (APS) is currently investigating replacing the existing two-bend 7 GeV lattice with a 6 GeV seven-bend achromat magnet lattice in order to achieve a low electron beam emittance [1]. This new lattice requires 1320 magnets, of which there are nine types. These include high strength quadrupoles (gradient up to ~97 T/m), sextupoles with second derivative of field up to ~7000 T/m2, longitudinal gradient dipoles with field ratio of up to 5, and transverse gradient dipoles with gradients of ~50 T/m and central field of ~0.6 T. These field requirements and the limited space available pose several design challenges. This paper presents a summary of magnet designs for the various magnet types developed through a collaboration of APS with FNAL and BNL.

  13. Achromatic half-wave plate for submillimeter instruments in cosmic microwave background astronomy: experimental characterization.

    PubMed

    Pisano, Giampaolo; Savini, Giorgio; Ade, Peter A R; Haynes, Vic; Gear, Walter K

    2006-09-20

    An achromatic half-wave plate (HWP) to be used in millimeter cosmic microwave background (CMB) polarization experiments has been designed, manufactured, and tested. The design is based on the 5-plates Pancharatnam recipe and it works in the frequency range 85-185 GHz. A model has been used to predict the transmission, reflection, absorption, and phase shift as a function of frequency. The HWP has been tested by using coherent radiation from a back-wave oscillator to investigate its modulation efficiency and with incoherent radiation from a polarizing Fourier transform spectrometer (FTS) to explore its frequency behavior. The FTS measurements have been fitted with an optical performance model which is in excellent agreement with the data. A detailed analysis of the data also allows a precise determination of the HWP fast and slow axes in the frequency band of operation. A list of the HWP performance characteristics is reported including estimates of its cross polarization.

  14. Visible-infrared achromatic imaging by wavefront coding with wide-angle automobile camera

    NASA Astrophysics Data System (ADS)

    Ohta, Mitsuhiko; Sakita, Koichi; Shimano, Takeshi; Sugiyama, Takashi; Shibasaki, Susumu

    2016-09-01

    We perform an experiment of achromatic imaging with wavefront coding (WFC) using a wide-angle automobile lens. Our original annular phase mask for WFC was inserted to the lens, for which the difference between the focal positions at 400 nm and at 950 nm is 0.10 mm. We acquired images of objects using a WFC camera with this lens under the conditions of visible and infrared light. As a result, the effect of the removal of the chromatic aberration of the WFC system was successfully determined. Moreover, we fabricated a demonstration set assuming the use of a night vision camera in an automobile and showed the effect of the WFC system.

  15. 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 ...

  16. Color: an exosomatic organ?

    NASA Astrophysics Data System (ADS)

    van Brakel, Jaap; Saunders, Barbara

    2001-12-01

    According to the dominant view in cognitive science, in particular in its more popularized versions, color sensings or perceptions are located in a 'quality space'. This space has three dimensions: hue (the chromatic aspect of color), saturation (the 'intensity' of hue), and brightness. This space is structured further via a small number of primitive hues or landmark colors, usually four (red, yellow, green, blue) or six (if white and black are included). It has also been suggested that there are eleven semantic universals - the six colors previously mentioned plus orange, pink, brown, purple, and grey. Scientific evidence for these widely accepted theories is at best minimal, based on sloppy methodology and at worst non-existent. Against the standard view, it is argued that color might better be regarded as the outcome of a social-historical developmental trajectory in which there is mutual shaping of philosophical presuppositions, scientific theories, experimental practices, technological tools, industrial products, rhetorical frameworks, and their intercalated and recursive interactions with the practices of daily life. That is: color, the domain of color, is the outcome of interactive processes of scientific, instrumental, industrial, and everyday lifeworlds. That is: color might better be called an exosomatic organ, a second nature.

  17. Illuminant color estimation based on pigmentation separation from human skin color

    NASA Astrophysics Data System (ADS)

    Tanaka, Satomi; Kakinuma, Akihiro; Kamijo, Naohiro; Takahashi, Hiroshi; Tsumura, Norimichi

    2015-03-01

    Human has the visual system called "color constancy" that maintains the perceptive colors of same object across various light sources. The effective method of color constancy algorithm was proposed to use the human facial color in a digital color image, however, this method has wrong estimation results by the difference of individual facial colors. In this paper, we present the novel color constancy algorithm based on skin color analysis. The skin color analysis is the method to separate the skin color into the components of melanin, hemoglobin and shading. We use the stationary property of Japanese facial color, and this property is calculated from the components of melanin and hemoglobin. As a result, we achieve to propose the method to use subject's facial color in image and not depend on the individual difference among Japanese facial color.

  18. Human preference for individual colors

    NASA Astrophysics Data System (ADS)

    Palmer, Stephen E.; Schloss, Karen B.

    2010-02-01

    Color preference is an important aspect of human behavior, but little is known about why people like some colors more than others. Recent results from the Berkeley Color Project (BCP) provide detailed measurements of preferences among 32 chromatic colors as well as other relevant aspects of color perception. We describe the fit of several color preference models, including ones based on cone outputs, color-emotion associations, and Palmer and Schloss's ecological valence theory. The ecological valence theory postulates that color serves an adaptive "steering' function, analogous to taste preferences, biasing organisms to approach advantageous objects and avoid disadvantageous ones. It predicts that people will tend to like colors to the extent that they like the objects that are characteristically that color, averaged over all such objects. The ecological valence theory predicts 80% of the variance in average color preference ratings from the Weighted Affective Valence Estimates (WAVEs) of correspondingly colored objects, much more variance than any of the other models. We also describe how hue preferences for single colors differ as a function of gender, expertise, culture, social institutions, and perceptual experience.

  19. Color harmonization for images

    NASA Astrophysics Data System (ADS)

    Tang, Zhen; Miao, Zhenjiang; Wan, Yanli; Wang, Zhifei

    2011-04-01

    Color harmonization is an artistic technique to adjust a set of colors in order to enhance their visual harmony so that they are aesthetically pleasing in terms of human visual perception. We present a new color harmonization method that treats the harmonization as a function optimization. For a given image, we derive a cost function based on the observation that pixels in a small window that have similar unharmonic hues should be harmonized with similar harmonic hues. By minimizing the cost function, we get a harmonized image in which the spatial coherence is preserved. A new matching function is proposed to select the best matching harmonic schemes, and a new component-based preharmonization strategy is proposed to preserve the hue distribution of the harmonized images. Our approach overcomes several shortcomings of the existing color harmonization methods. We test our algorithm with a variety of images to demonstrate the effectiveness of our approach.

  20. Color appearance in stereoscopy

    NASA Astrophysics Data System (ADS)

    Gadia, Davide; Rizzi, Alessandro; Bonanomi, Cristian; Marini, Daniele; Galmonte, Alessandra; Agostini, Tiziano

    2011-03-01

    The relationship between color and lightness appearance and the perception of depth has been studied since a while in the field of perceptual psychology and psycho-physiology. It has been found that depth perception affects the final object color and lightness appearance. In the stereoscopy research field, many studies have been proposed on human physiological effects, considering e.g. geometry, motion sickness, etc., but few has been done considering lightness and color information. Goal of this paper is to realize some preliminar experiments in Virtual Reality in order to determine the effects of depth perception on object color and lightness appearance. We have created a virtual test scene with a simple 3D simultaneous contrast configuration. We have created three different versions of this scene, each with different choices of relative positions and apparent size of the objects. We have collected the perceptual responses of several users after the observation of the test scene in the Virtual Theater of the University of Milan, a VR immersive installation characterized by a semi-cylindrical screen that covers 120° of horizontal field of view from an observation distance of 3.5 m. We present a description of the experiments setup and procedure, and we discuss the obtained results.

  1. The Color Lexica of Two American Indian Languages, Quechi and Misquito: A Critical Contribution to the Application of the Whorf Thesis to Color Naming

    ERIC Educational Resources Information Center

    von Wattenwyl, Andre; Zollinger, Heinrich

    1978-01-01

    Studies the link between the theory of the neurophysiology of color perception and Berlin and Kay's ideas on color linguistics and color perception. Two interpretations of studies of color terminology are shown, one supporting and one disproving the Whorf Thesis. (NCR)

  2. Graphemes Sharing Phonetic Features Tend to Induce Similar Synesthetic Colors

    PubMed Central

    Kang, Mi-Jeong; Kim, Yeseul; Shin, Ji-Young; Kim, Chai-Youn

    2017-01-01

    Individuals with grapheme-color synesthesia experience idiosyncratic colors when viewing achromatic letters or digits. Despite large individual differences in grapheme-color association, synesthetes tend to associate graphemes sharing a perceptual feature with similar synesthetic colors. Sound has been suggested as one such feature. In the present study, we investigated whether graphemes of which representative phonemes have similar phonetic features tend to be associated with analogous synesthetic colors. We tested five Korean multilingual synesthetes on a color-matching task using graphemes from Korean, English, and Japanese orthography. We then compared the similarity of synesthetic colors induced by those characters sharing a phonetic feature. Results showed that graphemes associated with the same phonetic feature tend to induce synesthetic color in both within- and cross-script analyses. Moreover, this tendency was consistent for graphemes that are not transliterable into each other as well as graphemes that are. These results suggest that it is the perceptual—i.e., phonetic—properties associated with graphemes, not just conceptual associations such as transliteration, that determine synesthetic color. PMID:28348537

  3. Color adaptation induced from linguistic description of color

    PubMed Central

    Zheng, Liling; Huang, Ping; Zhong, Xiao; Li, Tianfeng; Mo, Lei

    2017-01-01

    Recent theories propose that language comprehension can influence perception at the low level of perceptual system. Here, we used an adaptation paradigm to test whether processing language caused color adaptation in the visual system. After prolonged exposure to a color linguistic context, which depicted red, green, or non-specific color scenes, participants immediately performed a color detection task, indicating whether they saw a green color square in the middle of a white screen or not. We found that participants were more likely to perceive the green color square after listening to discourses denoting red compared to discourses denoting green or conveying non-specific color information, revealing that language comprehension caused an adaptation aftereffect at the perceptual level. Therefore, semantic representation of color may have a common neural substrate with color perception. These results are in line with the simulation view of embodied language comprehension theory, which predicts that processing language reactivates the sensorimotor systems that are engaged during real experience. PMID:28358807

  4. A Proposal of Color Correction Method with Self-Organizing Maps for Personal User's Visibility on the Web Browsing

    NASA Astrophysics Data System (ADS)

    Hiramatsu, Akiko; Notomi, Kazuhiro; Saito, Keiichi

    In this article, we describe a Web browsing method with an automatic color correction (palette changing) for personal user's visibility. Especially we describe a paired comparison test and SOM (Self-Organizing Map) analysis for achromatic character colors and chromatic background colors. We are implementing and evaluating a web application system for this method as CGI (Common Gateway Interface) software on a HTTP server of the Internet. Since a user profiling is required beforehand for every user, we considered about this problem with SOM.

  5. A new class of chromatic filters for color image processing. Theory and applications.

    PubMed

    Lucchese, Luca; Mitra, Sanjit K

    2004-04-01

    This paper advances a new framework for chromatic filtering of color images. The chromatic content of a color image is encoded in the CIE u'v' chromaticity coordinates whereas the achromatic content is encoded as CIE Y tristimulus value. Within the u'v' chromaticity diagram, colors are added according to the well-known center of gravity law of additive color mixtures, which is generalized here into a nonlinear filtering scheme for processing the two chromatic signals u' and v'. The achromatic channel Y can be processed with traditional filtering schemes, either linear or nonlinear, depending on the specific task at hand. The most interesting characteristics of the new filtering scheme are: 1) the elimination of color smearing effects along edges between bright and dark areas; 2) the possibility of processing chromatic components in a noniterative fashion through linear convolution operations; and 3) the consequent amenability to computationally efficient implementations with fast Fourier transform. The paper includes several examples with both synthetic and real images where the performance of the new filtering method is compared with that of other color image processing algorithms.

  6. A Study on Visibility Estimation of Web-Safe Colors using Paired Comparison and Discriminant Analysis

    NASA Astrophysics Data System (ADS)

    Saito, Daisuke; Saito, Keiichi; Notomi, Kazuhiro; Saito, Masao

    This paper presents the visibility ordering of several web safe colors. The research of web page visibility is important because of the rapid dissemination of the World Wide Web. The combination of a foreground color and a background color is an important factor in providing sufficient visibility. Therefore, the rating of color combination visibility is necessary when developing accessible web sites. In this study, the visibility of several web-safe color combinations was examined using psychological methodology, i.e., paired comparison. Eighteen chromatic and 3 achromatic web-safe colors were employed for visual stimuli. Twenty-eight subjects ranging from ages 21 to 75 were recruited, and all were with normal color sensation. They looked at two different colored characters simultaneously on the white background and were instructed to identify which one enabled them to see more clearly. In examining the relationship between the psychological rankings of the color combinations and the visual sensations, each color combination was first scored as to the visibility by Thurstone's paired comparison technique. Secondly, the visual sensation was deduced by applying Weber-Fechner's law to the luminance of the foreground colors. As results, the luminance of a foreground color influenced the visibility; however the visibility rating is difficult only using the luminance of web-safe colors. These indicate that the chromaticity and chroma saturation are necessary in rating of chromatic web-safe color visibility.

  7. Design of a triple-bend isochronous achromat with minimum coherent-synchrotron-radiation-induced emittance growth

    NASA Astrophysics Data System (ADS)

    Venturini, M.

    2016-06-01

    Using a 1D steady-state free-space coherent synchrotron radiation (CSR) model, we identify a special design setting for a triple-bend isochronous achromat that yields vanishing emittance growth from CSR. When a more refined CSR model with transient effects is included in the analysis, numerical simulations show that the main effect of the transients is to shift the emittance growth minimum slightly, with the minimum changing only modestly.

  8. The Whole is Other Than the Sum: Perceived Contrast Summation Within Color and Luminance Plaids

    PubMed Central

    Cherniawsky, Avital S.

    2016-01-01

    The apparent contrast of a plaid is a reflection of the neural relationship between the responses to its two orthogonal component gratings. To investigate the perceived contrast summation of the responses to component gratings in plaids, we compared the apparent contrasts of monocular plaids to a component grating presented alone across chromaticity and spatial frequency. Observers performed a contrast-matching task for red–green color and luminance stimuli at low- and medium-spatial frequencies. Using the measured points of subjective equality between plaids and gratings, we evaluate perceived contrast summation across conditions, which may vary between 1 (no summation) and 2 (full summation). We show that achromatic plaids have higher perceived contrast summation than chromatic plaids. The greatest difference occurs at the medium-spatial frequency, with summation highest for achromatic plaids (1.87) and lowest for chromatic plaids (1.49), while at low-spatial frequencies, there is a smaller summation difference between achromatic (1.72) and chromatic (1.65) plaids. These results are consistent with recent theories of distinct cross-orientation suppression and summation mechanisms in color and luminance vision. Two control experiments for binocular versus monocular viewing, and the overall size of the stimulus patches did not reveal any differences from our main results. PMID:27822354

  9. Preventing HIV among U.S. women of color with severe mental illness: perceptions of mental health care providers working in urban community clinics.

    PubMed

    Agénor, Madina; Collins, Pamela Y

    2013-01-01

    Given their knowledge of the behavioral issues related to psychiatric illness, mental health care providers are in a unique position to help prevent HIV among women with severe mental illness (SMI). We conducted in-depth interviews with providers at two New York City community clinics. We identified three major, interrelated themes pertaining to HIV prevention among women of color with SMI. Interventions that address the barriers that clinicians face in discussing sex, sexuality, and HIV with patients and train providers in the cultural considerations of cross-cultural mental health care are needed to help prevent HIV among women of color with SMI.

  10. An Easy Way to Show Memory Color Effects

    PubMed Central

    2016-01-01

    This study proposes and evaluates a simple stimulus display that allows one to measure memory color effects (the effect of object knowledge and memory on color perception). The proposed approach is fast and easy and does not require running an extensive experiment. It shows that memory color effects are robust to minor variations due to a lack of color calibration. PMID:27698988

  11. Interaction between facial expression and color

    PubMed Central

    Nakajima, Kae; Minami, Tetsuto; Nakauchi, Shigeki

    2017-01-01

    Facial color varies depending on emotional state, and emotions are often described in relation to facial color. In this study, we investigated whether the recognition of facial expressions was affected by facial color and vice versa. In the facial expression task, expression morph continua were employed: fear-anger and sadness-happiness. The morphed faces were presented in three different facial colors (bluish, neutral, and reddish color). Participants identified a facial expression between the two endpoints (e.g., fear or anger) regardless of its facial color. The results showed that the perception of facial expression was influenced by facial color. In the fear-anger morphs, intermediate morphs of reddish-colored and bluish colored faces had a greater tendency to be identified as angry faces and fearful faces, respectively. In the facial color task, two bluish-to-reddish colored face continua were presented in three different facial expressions (fear-neutral-anger and sadness-neutral-happiness). Participants judged whether the facial color was reddish or bluish regardless of its expression. The faces with sad expression tended to be identified as more bluish, while the faces with other expressions did not affect facial color judgment. These results suggest that an interactive but disproportionate relationship exists between facial color and expression in face perception. PMID:28117349

  12. Modeling, Measuring, and Compensating Color Weak Vision.

    PubMed

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-06-01

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color-weak observers. The two main applications are the simulation of the perception of a color weak observer for a color-normal observer, and the compensation of color images in a way that a color-weak observer has approximately the same perception as a color-normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticeable-differences between the colors which are measured with the help of color-matching experiments. The constructed mappings are the isometries of Riemann spaces that preserve the perceived color differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared with the previously used methods, this method is free from approximation errors due to local linearizations, and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyze the variations of the Riemann metrics for different observers obtained from new color-matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential tests.

  13. Modelling, Measuring and Compensating Color Weak Vision.

    PubMed

    Oshima, Satoshi; Mochizuki, Rika; Lenz, Reiner; Chao, Jinhui

    2016-03-08

    We use methods from Riemann geometry to investigate transformations between the color spaces of color-normal and color weak observers. The two main applications are the simulation of the perception of a color weak observer for a color normal observer and the compensation of color images in a way that a color weak observer has approximately the same perception as a color normal observer. The metrics in the color spaces of interest are characterized with the help of ellipsoids defined by the just-noticable-differences between color which are measured with the help of color-matching experiments. The constructed mappings are isometries of Riemann spaces that preserve the perceived color-differences for both observers. Among the two approaches to build such an isometry, we introduce normal coordinates in Riemann spaces as a tool to construct a global color-weak compensation map. Compared to previously used methods this method is free from approximation errors due to local linearizations and it avoids the problem of shifting locations of the origin of the local coordinate system. We analyse the variations of the Riemann metrics for different observers obtained from new color matching experiments and describe three variations of the basic method. The performance of the methods is evaluated with the help of semantic differential (SD) tests.

  14. Accelerated one-step generation of full-color holographic videos using a color-tunable novel-look-up-table method for holographic three-dimensional television broadcasting

    PubMed Central

    Kim, Seung-Cheol; Dong, Xiao-Bin; Kim, Eun-Soo

    2015-01-01

    A color-tunable novel-look-up-table (CT-NLUT) for fast one-step calculation of full-color computer-generated holograms is proposed. The proposed method is composed of four principal fringe patterns (PFPs) such as a baseline, a depth-compensating and two color-compensating PFPs. CGH patterns for one color are calculated by combined use of baseline-PFP and depth-compensating-PFP and from them, those for two other colors are generated by being multiplied by the corresponding color-compensating-PFPs. color-compensating-PFPs compensate for differences in the wavelength between two colors based on their unique achromatic thin-lens properties, enabling transformation of one-color CGH pattern into those for other colors. This color-conversion property of the proposed method enables simultaneous generation of full color-CGH patterns, resulting in a significant reduction of the full color-CGH calculation time. Experimental results with test scenario show that the full color-CGH calculation time of the proposed CT-NLUT has been reduced by 45.10%, compared to the conventional NLUT. It has been further reduced by 96.01% when a data compression algorithm, called temporal redundancy-based NLUT, was used together, which means 25-fold reduction of its full color-CGH calculation time. Successful computational and optical reconstructions of full color-CGH patterns confirm the feasibility of the proposed method. PMID:26358334

  15. Accelerated one-step generation of full-color holographic videos using a color-tunable novel-look-up-table method for holographic three-dimensional television broadcasting.

    PubMed

    Kim, Seung-Cheol; Dong, Xiao-Bin; Kim, Eun-Soo

    2015-09-11

    A color-tunable novel-look-up-table (CT-NLUT) for fast one-step calculation of full-color computer-generated holograms is proposed. The proposed method is composed of four principal fringe patterns (PFPs) such as a baseline, a depth-compensating and two color-compensating PFPs. CGH patterns for one color are calculated by combined use of baseline-PFP and depth-compensating-PFP and from them, those for two other colors are generated by being multiplied by the corresponding color-compensating-PFPs. color-compensating-PFPs compensate for differences in the wavelength between two colors based on their unique achromatic thin-lens properties, enabling transformation of one-color CGH pattern into those for other colors. This color-conversion property of the proposed method enables simultaneous generation of full color-CGH patterns, resulting in a significant reduction of the full color-CGH calculation time. Experimental results with test scenario show that the full color-CGH calculation time of the proposed CT-NLUT has been reduced by 45.10%, compared to the conventional NLUT. It has been further reduced by 96.01% when a data compression algorithm, called temporal redundancy-based NLUT, was used together, which means 25-fold reduction of its full color-CGH calculation time. Successful computational and optical reconstructions of full color-CGH patterns confirm the feasibility of the proposed method.

  16. Temperature- and wavelength-insensitive parametric amplification enabled by noncollinear achromatic phase-matching

    PubMed Central

    Tang, Daolong; Ma, Jingui; Wang, Jing; Zhou, Bingjie; Xie, Guoqiang; Yuan, Peng; Zhu, Heyuan; Qian, Liejia

    2016-01-01

    Optical parametric chirped-pulse amplification (OPCPA) has been demonstrated to be a promising approach for pushing femtosecond pulses towards ultra-high peak powers. However, the future success of OPCPA strongly relies on the ability to manipulate its phase-matching (PM) configuration. When a high average power pump laser is involved, the thermal effects in nonlinear crystals induce phase-mismatch distortions that pose an inherent limitation on the conversion efficiency. Here, we demonstrate that the noncollinear configuration previously adopted for wavelength-insensitive PM can be employed for temperature-insensitive PM when the noncollinear angle is properly reset. Simultaneous temperature- and wavelength-insensitive PM is realized for the first time by imposing such a temperature-insensitive noncollinear configuration with an angularly dispersed seed signal. Based on the lithium triborate crystal, the proposed noncollinear achromatic PM has a thermal acceptance 6 times larger than that of the conventional wavelength-insensitive noncollinear PM and has a sufficient spectral acceptance to support pulse durations of ~20 fs at 800 nm. These achievements open new possibilities for generating ultra-high peak power lasers with high average power. PMID:27786299

  17. Achromatic registration of quadrature components of the optical spectrum in spectral domain optical coherence tomography

    SciTech Connect

    Shilyagin, P A; Gelikonov, G V; Gelikonov, V M; Moiseev, A A; Terpelov, D A

    2014-07-31

    We have thoroughly investigated the method of simultaneous reception of spectral components with the achromatised quadrature phase shift between two portions of a reference wave, designed for the effective suppression of the 'mirror' artefact in the resulting image obtained by means of spectral domain optical coherence tomography (SD OCT). We have developed and experimentally tested a phase-shifting element consisting of a beam divider, which splits the reference optical beam into the two beams, and of delay lines being individual for each beam, which create a mutual phase difference of π/2 in the double pass of the reference beam. The phase shift achromatism over a wide spectral range is achieved by using in the delay lines the individual elements with different dispersion characteristics. The ranges of admissible adjustment parameters of the achromatised delay line are estimated for exact and inexact conformity of the geometric characteristics of its components to those calculated. A possibility of simultaneous recording of the close-to-quadrature spectral components with a single linear photodetector element is experimentally confirmed. The suppression of the artefact mirror peak in the OCT-signal by an additional 9 dB relative to the level of its suppression is experimentally achieved when the air delay line is used. Two-dimensional images of the surface positioned at an angle to the axis of the probe beam are obtained with the correction of the 'mirror' artefact while maintaining the dynamic range of the image. (laser biophotonics)

  18. Reduction of Beam Emittance of Pep-X Using Quadruple Bend Achromat Cell

    SciTech Connect

    Wang, Min-Huey; Cai, Yunhai; Hettel, Robert; Nosochkov, Yuri; /SLAC

    2009-05-26

    SLAC National Accelerator Laboratory is studying an option of building a high brightness synchrotron light source machine, PEP-X, in the existing PEP-II tunnel [1, 2]. By replacing 6 arcs of FODO cells of PEPII High Energy Ring (HER) with two arcs of DBA and four arcs of TME and installation of 89.3 m long damping wiggler an ultra low beam emittance of 0.14 nm-rad (including intra-beam scattering) at 4.5 GeV is achieved. In this paper we study the possibility to further reduce the beam emittance by releasing the constraint of the dispersion free in the DBA straight. The QBA (Quadruple Bend Achromat) cell is used to replace the DBA. The ratio of outer and inner bending angle is optimized. The dispersion function in the non-dispersion straight is controlled to compromise with lower emittance and beam size at the dispersion straight. An undulator of period length 23 mm, maximum magnetic field of 1.053 T, and total periods of 150 is used to put in the 30 straights to simulate the effects of these IDs on the beam emittance and energy spread. The brightness including all the ID effects is calculated and compared to the original PEP-X design.

  19. Needle endomicroscope with a plastic, achromatic objective to perform optical biopsies of breast tissue

    NASA Astrophysics Data System (ADS)

    Kyrish, Matthew; Dobbs, Jessica; Richards-Kortum, Rebecca; Tkaczyk, Tomasz

    2013-03-01

    In order to diagnose cancer in breast tissue, a sample must be removed, prepared, and examined under a microscope. To provide an alternative to conventional biopsies, an endomicroscope intended to perform optical biopsies is demonstrated. The system provides high resolution, high contrast images in real-time which could allow a diagnosis to be made during surgery without the need for tissue removal. Optical sectioning is achieved via structured illumination to reject out of focus light. An image is relayed between the sample plane and the imaging system by a coherent fiber bundle with an achromatized objective lens at the distal tip of the fiber bundle which is the diameter of a biopsy needle. The custom, plastic objective provides correction for both the excitation and emission wavelengths of proflavine (452 nm and 515 nm, respectively). It also magnifies the object onto the distal tip of the fiber bundle to increase lateral resolution. The lenses are composed of the optical plastics Zeonex E48R, PMMA, and polystyrene. The lenses are fabricated via single point diamond turning and assembled using a zero alignment technique. The lateral resolution and chromatic focal shift were measured and in vitro images of breast carcinoma cells stained with proflavine were captured. The optical biopsy system is able to achieve optical sectioning and to resolve smaller features than the current high resolution microendoscope.

  20. Temperature- and wavelength-insensitive parametric amplification enabled by noncollinear achromatic phase-matching

    NASA Astrophysics Data System (ADS)

    Tang, Daolong; Ma, Jingui; Wang, Jing; Zhou, Bingjie; Xie, Guoqiang; Yuan, Peng; Zhu, Heyuan; Qian, Liejia

    2016-10-01

    Optical parametric chirped-pulse amplification (OPCPA) has been demonstrated to be a promising approach for pushing femtosecond pulses towards ultra-high peak powers. However, the future success of OPCPA strongly relies on the ability to manipulate its phase-matching (PM) configuration. When a high average power pump laser is involved, the thermal effects in nonlinear crystals induce phase-mismatch distortions that pose an inherent limitation on the conversion efficiency. Here, we demonstrate that the noncollinear configuration previously adopted for wavelength-insensitive PM can be employed for temperature-insensitive PM when the noncollinear angle is properly reset. Simultaneous temperature- and wavelength-insensitive PM is realized for the first time by imposing such a temperature-insensitive noncollinear configuration with an angularly dispersed seed signal. Based on the lithium triborate crystal, the proposed noncollinear achromatic PM has a thermal acceptance 6 times larger than that of the conventional wavelength-insensitive noncollinear PM and has a sufficient spectral acceptance to support pulse durations of ~20 fs at 800 nm. These achievements open new possibilities for generating ultra-high peak power lasers with high average power.

  1. Designing of the low energy beam lines with achromatic condition in the RAON accelerator

    NASA Astrophysics Data System (ADS)

    Jin, Hyunchang; Jang, Ji-Ho; Jeon, Dong-O.

    2017-01-01

    The RAON accelerator has been built to create and accelerate stable heavy-ion beams and rare isotope beams. The stable heavy-ion beams are generated by the superconducting electron cyclotron resonance ion source and accelerated by the low energy superconducting linac SCL1. The beams accelerated by the SCL1 are re-accelerated by the high energy superconducting linac SCL2 for the generation of rare isotope beams by using the in-flight fragmentation system or are put to use in the low energy experimental halls, which include the neutron science facility and the KOrea Broad acceptance Recoil spectrometer and Apparatus after having passed through the low energy beam lines which have long deflecting sections. At the end of each beam line in the low energy experimental halls, the beams should meet the targets of the two facilities with the specific requirements satisfied. Namely, if the beam is to be sent safely and accurately to the targets and simultaneously, satisfy the requirements, an achromatic lattice design needs to be applied in each beam line. In this paper, we will present the lattice design of the low energy beam lines and describe the results of the beam dynamics simulations. In addition, the correction of the beam orbit, which is distorted by machine imperfections, will be discussed.

  2. Needle-based fluorescence endomicroscopy via structured illumination with a plastic, achromatic objective

    PubMed Central

    Kyrish, Matthew; Dobbs, Jessica; Jain, Shalini; Wang, Xiao; Yu, Dihua; Richards-Kortum, Rebecca

    2013-01-01

    Abstract. In order to diagnose cancer, a sample must be removed, prepared, and examined under a microscope, which is expensive, invasive, and time consuming. Fiber optic fluorescence endomicroscopy, where an image guide is used to obtain high-resolution images of tissue in vivo, has shown promise as an alternative to conventional biopsies. However, the resolution of standard endomicroscopy is limited by the fiber bundle sampling frequency and out-of-focus light. A system is presented which incorporates a plastic, achromatic objective to increase the sampling and which provides optical sectioning via structured illumination to reject background light. An image is relayed from the sample by a fiber bundle with the custom 2.1-mm outer diameter objective lens integrated to the distal tip. The objective is corrected for the excitation and the emission wavelengths of proflavine (452 and 515 nm). It magnifies the object onto the fiber bundle to improve the system’s lateral resolution by increasing the sampling. The plastic lenses were fabricated via single-point diamond turning and assembled using a zero alignment technique. Ex vivo images of normal and neoplastic murine mammary tissues stained with proflavine are captured. The system achieves higher contrast and resolves smaller features than standard fluorescence endomicroscopy. PMID:24002190

  3. 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.

  4. Glossiness of Colored Papers based on Computer Graphics Model and Its Measuring Method

    NASA Astrophysics Data System (ADS)

    Aida, Teizo

    In the case of colored papers, the color of surface effects strongly upon the gloss of its paper. The new glossiness for such a colored paper is suggested in this paper. First, using the Achromatic and Chromatic Munsell colored chips, the author obtained experimental equation which represents the relation between lightness V ( or V and saturation C ) and psychological glossiness Gph of these chips. Then, the author defined a new glossiness G for the colored papers, based on the above mentioned experimental equations Gph and Cook-Torrance's reflection model which are widely used in the filed of Computer Graphics. This new glossiness is shown to be nearly proportional to the psychological glossiness Gph. The measuring system for the new glossiness G is furthermore descrived. The measuring time for one specimen is within 1 minute.

  5. Entropy, color, and color rendering.

    PubMed

    Price, Luke L A

    2012-12-01

    The Shannon entropy [Bell Syst. Tech J.27, 379 (1948)] of spectral distributions is applied to the problem of color rendering. With this novel approach, calculations for visual white entropy, spectral entropy, and color rendering are proposed, indices that are unreliant on the subjectivity inherent in reference spectra and color samples. The indices are tested against real lamp spectra, showing a simple and robust system for color rendering assessment. The discussion considers potential roles for white entropy in several areas of color theory and psychophysics and nonextensive entropy generalizations of the entropy indices in mathematical color spaces.

  6. Color Algebras

    NASA Technical Reports Server (NTRS)

    Mulligan, Jeffrey B.

    2017-01-01

    A color algebra refers to a system for computing sums and products of colors, analogous to additive and subtractive color mixtures. We would like it to match the well-defined algebra of spectral functions describing lights and surface reflectances, but an exact correspondence is impossible after the spectra have been projected to a three-dimensional color space, because of metamerism physically different spectra can produce the same color sensation. Metameric spectra are interchangeable for the purposes of addition, but not multiplication, so any color algebra is necessarily an approximation to physical reality. Nevertheless, because the majority of naturally-occurring spectra are well-behaved (e.g., continuous and slowly-varying), color algebras can be formulated that are largely accurate and agree well with human intuition. Here we explore the family of algebras that result from associating each color with a member of a three-dimensional manifold of spectra. This association can be used to construct a color product, defined as the color of the spectrum of the wavelength-wise product of the spectra associated with the two input colors. The choice of the spectral manifold determines the behavior of the resulting system, and certain special subspaces allow computational efficiencies. The resulting systems can be used to improve computer graphic rendering techniques, and to model various perceptual phenomena such as color constancy.

  7. Color Facsimile.

    DTIC Science & Technology

    1995-02-01

    modification of existing JPEG compression and decompression software available from Independent JPEG Users Group to process CIELAB color images and to use...externally specificed Huffman tables. In addition a conversion program was written to convert CIELAB color space images to red, green, blue color space

  8. 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…

  9. Utilizing typical color appearance models to represent perceptual brightness and colorfulness for digital images

    NASA Astrophysics Data System (ADS)

    Gong, Rui; Wang, Qing; Shao, Xiaopeng; Zhou, Conghao

    2016-12-01

    This study aims to expand the applications of color appearance models to representing the perceptual attributes for digital images, which supplies more accurate methods for predicting image brightness and image colorfulness. Two typical models, i.e., the CIELAB model and the CIECAM02, were involved in developing algorithms to predict brightness and colorfulness for various images, in which three methods were designed to handle pixels of different color contents. Moreover, massive visual data were collected from psychophysical experiments on two mobile displays under three lighting conditions to analyze the characteristics of visual perception on these two attributes and to test the prediction accuracy of each algorithm. Afterward, detailed analyses revealed that image brightness and image colorfulness were predicted well by calculating the CIECAM02 parameters of lightness and chroma; thus, the suitable methods for dealing with different color pixels were determined for image brightness and image colorfulness, respectively. This study supplies an example of enlarging color appearance models to describe image perception.

  10. Object color affects identification and repetition priming.

    PubMed

    Uttl, Bob; Graf, Peter; Santacruz, Pilar

    2006-10-01

    We investigated the influence of color on the identification of both non-studied and studied objects. Participants studied black and white and color photos of common objects and memory was assessed with an identification test. Consistent with our meta-analysis of prior research, we found that objects were easier to identify from color than from black and white photos. We also found substantial priming in all conditions, and study-to-test changes in an object's color reduced the magnitude of priming. Color-specific priming effects were large for color-complex objects, but minimal for color-simple objects. The pattern and magnitude of priming effects was not influenced either by the extent to which an object always appears in the same color (i.e., whether a color is symptomatic of an object) or by the object's origin (natural versus fabricated). We discuss the implications of our findings for theoretical accounts of object perception and repetition priming.

  11. The ecological drivers of nuptial color evolution in darters (Percidae: Etheostomatinae).

    PubMed

    Ciccotto, Patrick J; Mendelson, Tamra C

    2016-04-01

    Closely related animal lineages often vary in male coloration, and ecological selection is hypothesized to shape this variation. The role of ecological selection in inhibiting male color has been documented extensively at the population level, but relatively few studies have investigated the evolution of male coloration across a clade of closely related species. Darters are a diverse group of fishes that vary in the presence of elaborate male nuptial coloration, with some species exhibiting vivid color patterns and others mostly or entirely achromatic. We used phylogenetic logistic regression to test for correlations between the presence/absence of color traits across darter species and the ecological conditions in which these species occur. Environmental variables were correlated with the presence of nuptial color in darters with colorful species tending to inhabit environments that would support fewer predators and potentially transmit a broader spectrum of natural light compared to species lacking male coloration. We also tested the color preferences of a common darter predator, largemouth bass, and found that it exhibits a strong preference for red, providing further evidence of predation as a source of selection on color evolution in darters. Ecological selection therefore appears to be an important factor in dictating the presence or absence of male coloration in this group of fishes.

  12. 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…

  13. 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…

  14. The relationship between perifoveal achromatic, L- and M-cone acuity and retinal structure as assessed with multimodal high resolution imaging.

    PubMed

    Baraas, Rigmor C; Gjelle, Jon V B; Finstad, Elisabeth Bratlie; Jacobsen, Siri Bjørnetun; Gilson, Stuart J

    2016-07-02

    The relationships between perifoveal measures of achromatic-, L- and M-cone acuity and retinal structure were investigated in healthy young males. Thirty-two males, aged 20-39years, with normal foveal logMAR letter acuity and no observed ocular abnormalities participated in the study. Achromatic and isolated L- and M-cone spatial acuity was measured in the dominant eye with a Sloan E letter of 90% achromatic decrement contrast or 23% increment cone contrast, respectively. Separately, the central part of the same eye was imaged with high-resolution spectral-domain optical coherence tomography (SD-OCT) and adaptive optics ophthalmoscopy (AOO). Thickness measures and cone density in the fovea and parafoveal region were not correlated with perifoveal structural measures. A significant correlation was observed between thicker retinal pigment epithelium (RPE) complex, higher cone density and better L-cone logMAR at 5deg eccentricity, but not for achromatic or M-cone logMAR. The results imply that single letter perifoveal L-cone acuity, rather than achromatic acuity, may provide a useful measure for assessing the structure-function relationship and detecting early changes in the perifoveal cone mosaic.

  15. Design of an achromatic and uncoupled medical gantry for radiation therapy

    SciTech Connect

    Tsoupas, N.; Kayran, D.; Litvinenko, V.; MacKay, W.W.

    2011-03-28

    We are presenting the layout and the optics of a beam line to be used as a medical gantry in radiation therapy. The optical properties of the gantry's beam line are such as to make the beam line achromatic and uncoupled. These two properties make the beam spot size, which is delivered and focused by the gantry, on the tumor of the patient, independent of the angular orientation of the gantry. In this paper we present the layout of the magnetic elements of the gantry, and also present the theoretical basis for the optics design of such a gantry. A medical gantry, as it is used in the radiation treatment of cancer patients, is the last part of the beam optical system, of the accelerator complex, which delivers and focuses the beam on the tumor. The curved line shown in figure 1 is a schematic diagram of a gantry which can rotate about a horizontal axis. The particle beam (green arrow in fig. 1) enters the gantry, and is guided by the gantry on the tumor (red spot in fig. 1). As the gantry rotates about the axis shown in figure 1, the beam exiting the gantry always lies on a plane normal to the rotation axis at the point of the icocenter. Thus the gantry facilitates the ability of the beam delivery system, to deliver the beam at the tumor, which is placed at the icocenter, from any angle on this vertical plane, which is normal to the rotation angle of the gantry as stated earlier. The gantry consists of dipoles and quadrupoles elements whose median symmetry plane lies on a plane which contains the rotation axis of the gantry. In this paper we define this plane as the 'plane of the gantry'. As the beam is transported along the axis of rotation of the gantry and before it enters the gantry, it is focused by 'normal' quadrupoles and experiences no linear beam coupling. Subsequently the beam enters the gantry, and is transported by the gantry to the delivery point which is the tumor. The transported beam at the tumor is still linearly uncoupled as long as the plane of the

  16. [Achromatic watercolor effect: about requirement of formation of sumi painting effect].

    PubMed

    Takashima, Midori

    2008-10-01

    The watercolor effect (Pinna, Brelstaff, & Spillmann, 2001) is a new color spreading phenomenon. Pinna et al. (2001) proposed that the watercolor effect is a new Gestalt factor because it determines figure-ground organization more strongly than classical Gestalt factors. We used achroriatic watercolor patterns and varied the lightness of the background and two border lines to study the relationship between the color spreading effect and figure-ground organization. The results demonstrated (a)a bidirectional color spreading phenomenon when the background lightness was between the two border-lines' lightness, and that (b) some patterns elicit only a color spreading effect without organization of figure-ground, while others elicit only figure-ground organization without a color spreading effect.

  17. Color terms and color concepts.

    PubMed

    Davidoff, Jules

    2006-08-01

    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 are taken up in the current commentary, especially with regard to the neuropsychological evidence. Data from aphasic patients also argue for a priority for abstract thought, but nevertheless it may still be that the use of color terms is the only way in which to form color categories even if both linguistic and attentional factors play an important role.

  18. Ratio model serves suprathreshold color- luminance discrimination

    NASA Astrophysics Data System (ADS)

    Sankeralli, Marcel J.; Mullen, Kathy T.; Hine, Trevor J.

    2002-03-01

    We extended earlier results [J. Opt. Soc. Am. A 16, 2625 (1999)] to examine how the responses of the three postreceptoral mechanisms are combined to subserve discrimination of suprathreshold stimuli. Test thresholds were obtained in the presence of suprathreshold pedestals selected in different quadrants of the red-green/luminance and blue-yellow/luminance planes of cardinal color space. We showed that (1) test threshold was directly proportional to pedestal contrast for pedestal contrasts exceeding five times pedestal contrast threshold, and (2) there were exceptions to this proportionality, notably when the test and pedestal directions were fixed in the cardinal directions. Results support a ratio model of suprathreshold color-luminance discrimination, in which discrimination depends on a ratio of outputs of the postreceptoral mechanisms. We also observed that when test threshold was measured as a function of test color-space direction, masking by the achromatic component of the pedestal was less than that by the chromatic component. In addition, masking by a dark (negative luminance component) pedestal was lower than masking by a light (positive luminance) pedestal of a similar contrast. Our results demonstrated that (1) there is no fundamental difference between discrimination in the isoluminant and in the two chromoluminant cardinal planes, (2) there exists the possibility that discrimination in cardinal directions differs from that in noncardinal (intermediate) directions, and (3) suprathreshold discrimination of luminance differences may be more sensitive than that of chromatic differences for a given suprathreshold pedestal.

  19. Extreme reaction times determine fluctuation scaling in human color vision

    NASA Astrophysics Data System (ADS)

    Medina, José M.; Díaz, José A.

    2016-11-01

    In modern mental chronometry, human reaction time defines the time elapsed from stimulus presentation until a response occurs and represents a reference paradigm for investigating stochastic latency mechanisms in color vision. Here we examine the statistical properties of extreme reaction times and whether they support fluctuation scaling in the skewness-kurtosis plane. Reaction times were measured for visual stimuli across the cardinal directions of the color space. For all subjects, the results show that very large reaction times deviate from the right tail of reaction time distributions suggesting the existence of dragon-kings events. The results also indicate that extreme reaction times are correlated and shape fluctuation scaling over a wide range of stimulus conditions. The scaling exponent was higher for achromatic than isoluminant stimuli, suggesting distinct generative mechanisms. Our findings open a new perspective for studying failure modes in sensory-motor communications and in complex networks.

  20. 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.

  1. 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…

  2. Human preferences for colorful birds: Vivid colors or pattern?

    PubMed

    Lišková, Silvie; Landová, Eva; Frynta, Daniel

    2015-04-29

    In a previous study, we found that the shape of a bird, rather than its color, plays a major role in the determination of human preferences. Thus, in the present study, we asked whether the preferences of human respondents towards uniformly shaped, colorful birds are determined by pattern rather than color. The experimental stimuli were pictures of small passerine birds of the family Pittidae possessing uniform shape but vivid coloration. We asked 200 participants to rank 43 colored and 43 identical, but grayscaled, pictures of birds. To find the traits determining human preferences, we performed GLM analysis in which we tried to explain the mean preference ranks and PC axes by the following explanatory variables: the overall lightness and saturation, edges (pattern), and the portion of each of the basic color hues. The results showed that the mean preference ranks of the grayscale set is explained mostly by the birds' pattern, whereas the colored set ranking is mostly determined by the overall lightness. The effect of colors was weaker, but still significant, and revealed that people liked blue and green birds. We found no significant role of the color red, the perception of which was acquired relatively recently in evolution.

  3. [Sensitivity and specificity of flicker perimetry with Pulsar. Comparison with achromatic (white-on-white) perimetry in glaucoma patients].

    PubMed

    Göbel, K; Erb, C

    2013-02-01

    The early detection of functional glaucoma damage plays an increasingly more central role in the diagnosis and treatment of glaucoma disease. Using selective perimetry detection of early glaucomatous defects is more likely and one of these methods is flicker perimetry with Pulsar. Flicker perimetry is used to analyze the temporal visual function in combination with spatial resolution and contrast sensitivity as opposed to standard automated perimetry which measures the differential light sensitivity with a non-specific stimulus. This study showed a higher sensitivity and specificity of Pulsar perimetry in comparison to achromatic perimetry in glaucoma patients.

  4. Perceptual transparency in neon color spreading displays.

    PubMed

    Ekroll, Vebjørn; Faul, Franz

    2002-08-01

    In neon color spreading displays, both a color illusion and perceptual transparency can be seen. In this study, we investigated the color conditions for the perception of transparency in such displays. It was found that the data are very well accounted for by a generalization of Metelli's (1970) episcotister model of balanced perceptual transparency to tristimulus values. This additive model correctly predicted which combinations of colors would lead to optimal impressions of transparency. Color combinations deviating slightly from the additive model also looked transparent, but less convincingly so.

  5. A color prediction model for imagery analysis

    NASA Technical Reports Server (NTRS)

    Skaley, J. E.; Fisher, J. R.; Hardy, E. E.

    1977-01-01

    A simple model has been devised to selectively construct several points within a scene using multispectral imagery. The model correlates black-and-white density values to color components of diazo film so as to maximize the color contrast of two or three points per composite. The CIE (Commission Internationale de l'Eclairage) color coordinate system is used as a quantitative reference to locate these points in color space. Superimposed on this quantitative reference is a perceptional framework which functionally contrasts color values in a psychophysical sense. This methodology permits a more quantitative approach to the manual interpretation of multispectral imagery while resulting in improved accuracy and lower costs.

  6. Achromatic-phase-shifting low-coherence digital holography: theoretical analyses of zero-phase-shifting error condition and linear and nonlinear calibrations

    NASA Astrophysics Data System (ADS)

    Hayasaki, Yoshio

    2015-10-01

    Some methods for decreasing a measurement error derived from a phase-shifting error for broadband light in phase-shifting low-coherence digital holography are proposed based on theoretical analysis and numerical calculations. It is well-known that an achromatic-phase shifter based on a rotating polarizer drastically decreases the error, but it is found that a small error remains according to the imperfection of the achromatic-phase shifter. It is also found that an ideal achromatic-phase shifter perfectly eliminates the error only when the light source has a symmetrical spectrum. Furthermore, it is demonstrated that a simple linear calibration method decreases the error in a narrow range of optical path differences if a light source with an asymmetrical spectrum is used. Finally, a nonlinear calibration method that can further decrease the error in a wide range of optical path differences is discussed.

  7. Uses of Color in Complex Information Displays

    DTIC Science & Technology

    1985-02-01

    Information Service database , the Lockheed Dialog System and the Defense File. The principal areas searched were: color perception, color coding, visual...computerized databases were also ident This search was multidisciplinary, covering relevant resea computer graphics, display technologies, human...saturated ones. This is true for all wavelengths, except spectral yellow (Chapanis & Halsey, 1955). While the scientific database remains incomplete

  8. Quantum Color

    ScienceCinema

    Lincoln, Don

    2016-07-20

    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.

  9. 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

  10. Achromatic optical compensation using dispersion of uniaxial films for elimination of off-axis light leakage in a liquid crystal cell.

    PubMed

    Oh, Seung-Won; Wok Park, Byung; Lee, Ji-Hoon; Yoon, Tae-Hoon

    2013-11-10

    We propose an achromatic optical-compensation method using uniaxial films to eliminate the off-axis light leakage at the dark state in a homogeneously aligned liquid crystal cell. Three uniaxial films with different dispersion characteristics are used so that they can compensate each other to achieve achromatic effective phase retardation at off-axis. The retardation values are optimized with the aid of the Poincaré sphere and through numerical research. A contrast ratio of higher than 2000∶1 is predicted over the entire ±60° viewing cone for a homogeneously aligned LC cell with zero pretilt angle.

  11. Quantifying nonhomogeneous colors in agricultural materials part I: method development.

    PubMed

    Balaban, M O

    2008-11-01

    Measuring the color of food and agricultural materials using machine vision (MV) has advantages not available by other measurement methods such as subjective tests or use of color meters. The perception of consumers may be affected by the nonuniformity of colors. For relatively uniform colors, average color values similar to those given by color meters can be obtained by MV. For nonuniform colors, various image analysis methods (color blocks, contours, and "color change index"[CCI]) can be applied to images obtained by MV. The degree of nonuniformity can be quantified, depending on the level of detail desired. In this article, the development of the CCI concept is presented. For images with a wide range of hue values, the color blocks method quantifies well the nonhomogeneity of colors. For images with a narrow hue range, the CCI method is a better indicator of color nonhomogeneity.

  12. Color Metric.

    ERIC Educational Resources Information Center

    Illinois State Office of Education, Springfield.

    This booklet was designed to convey metric information in pictoral form. The use of pictures in the coloring book enables the more mature person to grasp the metric message instantly, whereas the younger person, while coloring the picture, will be exposed to the metric information long enough to make the proper associations. Sheets of the booklet…

  13. Reflectance, illumination, and appearance in color constancy

    PubMed Central

    McCann, John J.; Parraman, Carinna; Rizzi, Alessandro

    2013-01-01

    We studied color constancy using a pair of identical 3-D Color Mondrian displays. We viewed one 3-D Mondrian in nearly uniform illumination, and the other in directional, nonuniform illumination. We used the three dimensional structures to modulate the light falling on the painted surfaces. The 3-D structures in the displays were a matching set of wooden blocks. Across Mondrian displays, each corresponding facet had the same paint on its surface. We used only 6 chromatic, and 5 achromatic paints applied to 104 block facets. The 3-D blocks add shadows and multiple reflections not found in flat Mondrians. Both 3-D Mondrians were viewed simultaneously, side-by-side. We used two techniques to measure correlation of appearance with surface reflectance. First, observers made magnitude estimates of changes in the appearances of identical reflectances. Second, an author painted a watercolor of the 3-D Mondrians. The watercolor's reflectances quantified the changes in appearances. While constancy generalizations about illumination and reflectance hold for flat Mondrians, they do not for 3-D Mondrians. A constant paint does not exhibit perfect color constancy, but rather shows significant shifts in lightness, hue and chroma in response to the structure in the nonuniform illumination. Color appearance depends on the spatial information in both the illumination and the reflectances of objects. The spatial information of the quanta catch from the array of retinal receptors generates sensations that have variable correlation with surface reflectance. Models of appearance in humans need to calculate the departures from perfect constancy measured here. This article provides a dataset of measurements of color appearances for computational models of sensation. PMID:24478738

  14. Color Functionality Used in Visual Display for Occupational and Environmental Safety and Managing Color Vision Deficiency.

    PubMed

    Ochiai, Nobuhisa; Kondo, Hiroyuki

    2017-01-01

    The effects of color perception are utilized in visual displays for the purpose of safety in the workplace and in daily life. These effects, generally known as color functionality, are divided into four classifications: visibility, legibility, conspicuity and discriminability. This article focuses on the relationship between the color functionality of color schemes used in visual displays for occupational and environmental safety and color vision deficiency (particularly congenital red-green color deficiency), a critical issue in ophthalmology, and examines the effects of color functionality on the perception of the color red in individuals with protan defects. Due to abrupt system reforms, current Japanese clinical ophthalmology finds itself in a situation where it is insufficiently prepared to handle congenital red-green color deficiencies. Indeed, occupational problems caused by color vision deficiencies have been almost completely neglected, and are an occupational safety and health concern that will need to be solved in the future. This report will present the guidelines for the color vision testing established by the British Health and Safety Executive (HSE), a pioneering example of a model meant to solve these problems. Issues relating to the creation of guidelines adapted to Japanese clinical ophthalmology will also be examined, and we will discuss ways to utilize color functionality used in visual displays for occupational and environmental safety to help manage color vision deficiency.

  15. Objective color harmony assessment for visible and infrared color fusion images of typical scenes

    NASA Astrophysics Data System (ADS)

    Gao, Shaoshu; Jin, Weiqi; Wang, Lingxue

    2012-11-01

    For visible and infrared color fusion images of three typical scenes, color harmony computational models are proposed to evaluate the color quality of fusion images without reference images. The models are established based on the color-combination harmony model and focus on the influence of the color characteristics of typical scenes and the color region sizes in the fusion image. For the influence of the color characteristics of typical scenes, color harmony adjusting factors for natural scene images (green plants, sea, and sky) are defined by measuring the similarity between image colors and corresponding memory colors, and that for town and building images are presented based on the optimum colorfulness range suited for a human. Simultaneously, considering the influence of color region sizes, the weight coefficients are established using areas of the color regions to optimize the color harmony model. Experimental results show that the proposed harmony models are consistent with human perception and that they are suitable to evaluate the color harmony for color fusion images of typical scenes.

  16. Different temporal structure for form versus surface cortical color systems--evidence from chromatic non-linear VEP.

    PubMed

    Crewther, David P; Crewther, Sheila G

    2010-12-20

    Physiological studies of color processing have typically measured responses to spatially varying chromatic stimuli such as gratings, while psychophysical studies of color include color naming, color and light, as well as spatial and temporal chromatic sensitivities. This raises the question of whether we have one or several cortical color processing systems. Here we show from non-linear analysis of human visual evoked potentials (VEP) the presence of distinct and independent temporal signatures for form and surface color processing. Surface color stimuli produced most power in the second order Wiener kernel, indicative of a slowly recovering neural system, while chromatic form stimulation produced most power in the first order kernel (showing rapid recovery). We find end-spectral saturation-dependent signals, easily separable from achromatic signals for surface color stimuli. However physiological responses to form color stimuli, though varying somewhat with saturation, showed similar waveform components. Lastly, the spectral dependence of surface and form color VEP was different, with the surface color responses almost vanishing with yellow-grey isoluminant stimulation whereas the form color VEP shows robust recordable signals across all hues. Thus, surface and form colored stimuli engage different neural systems within cortex, pointing to the need to establish their relative contributions under the diverse chromatic stimulus conditions used in the literature.

  17. The Computation of Color

    DTIC Science & Technology

    1989-09-01

    reviews 14 cases of achromatopsia due to cerebral lesions, the earliest being MacKay and Dunlop’s of 1899 [69], the latest one of his own (1974). All but...Meadows [81] and Damasio et. al. [20] note, this is supported by the fact that prosopagnosia and achromatopsia may occur independently of each other... achromatopsia in a patient (C. B.) who suffered occipital lobe damage in an auto accident. C.B.’s color perception is "grossly impaired," as evidenced by

  18. A Common Neural Substrate for Perceiving and Knowing about Color

    ERIC Educational Resources Information Center

    Simmons, W. Kyle; Ramjee, Vimal; Beauchamp, Michael S.; McRae, Ken; Martin, Alex; Barsalou, Lawrence W.

    2007-01-01

    Functional neuroimaging research has demonstrated that retrieving information about object-associated colors activates the left fusiform gyrus in posterior temporal cortex. Although regions near the fusiform have previously been implicated in color perception, it remains unclear whether color knowledge retrieval actually activates the color…

  19. Quantum Color

    SciTech Connect

    Lincoln, Don

    2016-07-05

    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.

  20. Perceptual issues for color helmet-mounted displays: luminance and color contrast requirements

    NASA Astrophysics Data System (ADS)

    Harding, Thomas H.; Rash, Clarence E.; Lattimore, Morris R.; Statz, Jonathan; Martin, John S.

    2016-05-01

    Color is one of the latest design characteristics of helmet-mounted displays (HMDs). It's inclusion in design specifications is based on two suppositions: 1) color provides an additional method of encoding information, and 2) color provides a more realistic, and hence more intuitive, presentation of information, especially pilotage imagery. To some degree, these two perceived advantages have been validated with head-down panel-mounted displays, although not without a few problems associated with visual physiology and perception. These problems become more prevalent when the user population expands beyond military aviators to a general user population, of which a significant portion may have color vision deficiencies. When color is implemented in HMDs, which are eyes-out, see-through displays, visual perception issues become an increased concern. A major confound with HMDs is their inherent see-through (transparent) property. The result is color in the displayed image combines with color from the outside (or in-cockpit) world, possibly producing a false perception of either or both images. While human-factors derived guidelines based on trial and error have been developed, color HMD systems still place more emphasis on colorimetric than perceptual standards. This paper identifies the luminance and color contrast requirements for see-through HMDs. Also included is a discussion of ambient scene metrics and the choice of symbology color.

  1. Lightness modification of color image for protanopia and deuteranopia

    NASA Astrophysics Data System (ADS)

    Tanaka, Go; Suetake, Noriaki; Uchino, Eiji

    2010-01-01

    In multimedia content, colors play important roles in conveying visual information. However, color information cannot always be perceived uniformly by all people. People with a color vision deficiency, such as dichromacy, cannot recognize and distinguish certain color combinations. In this paper, an effective lightness modification method, which enables barrier-free color vision for people with dichromacy, especially protanopia or deuteranopia, while preserving the color information in the original image for people with standard color vision, is proposed. In the proposed method, an optimization problem concerning lightness components is first defined by considering color differences in an input image. Then a perceptible and comprehensible color image for both protanopes and viewers with no color vision deficiency or both deuteranopes and viewers with no color vision deficiency is obtained by solving the optimization problem. Through experiments, the effectiveness of the proposed method is illustrated.

  2. Pattern glare: the effects of contrast and color

    PubMed Central

    Monger, Laura J.; Wilkins, Arnold J.; Allen, Peter M.

    2015-01-01

    Aim: To test a theory of visual stress by investigating the inter-relationships between (1) the threshold contrast/saturation at which individuals first report discomfort when viewing colored gratings of progressively increasing contrast and decreasing saturation; (2) the choice of a colored overlay for reading; (3) any increase in reading speed when the overlay is used. Method: Ninety-five young adults, with normal color vision, reported illusions from square-wave gratings (Pattern Glare Test), chose any colored overlays that improved clarity (Intuitive Color Overlays) and read aloud randomly ordered common words (Wilkins Rate of Reading Test). This was followed by an automated choice of tints for text using various screen colors on a tablet, and a test of discomfort from patterns of progressively increasing contrast and decreasing saturation, using software developed for this study. All participants wore their optimal refractive correction throughout the procedure. Results: Fifty-eight participants chose a colored overlay and reported that it made text easier and more comfortable to read. On average, these individuals had a greater improvement in reading speed with their overlays (p = 0.003), a lower contrast threshold at which discomfort from achromatic gratings was first reported (p = 0.015), and a tendency to report more pattern glare (p = 0.052), compared to the other participants. Participants who chose both a most and least preferred tint for text using the automated procedure reported discomfort from colored gratings at a significantly higher contrast with their most preferred color compared to their least preferred color (p = 0.003). The choice of a colored tint was moderately consistent across tests. The most and least preferred colors tended to be complementary. Conclusion: Colored tints that improved reading speed reduced pattern glare both in terms of the illusion susceptibility and in terms of discomfort contrast threshold, supporting a theory of

  3. When concepts lose their color: a case of object-color knowledge impairment.

    PubMed

    Stasenko, Alena; Garcea, Frank E; Dombovy, Mary; Mahon, Bradford Z

    2014-09-01

    Color is important in our daily interactions with objects, and plays a role in both low- and high-level visual processing. Previous neuropsychological studies have shown that color perception and object-color knowledge can doubly dissociate, and that both can dissociate from processing of object form. We present a case study of an individual who displayed an impairment for knowledge of the typical colors of objects, with preserved color perception and color naming. Our case also presented with a pattern of, if anything, worse performance for naming living items compared to non-living things. The findings of the experimental investigation are evaluated in light of two theories of conceptual organization in the brain: the Sensory/Functional Theory and the Domain-Specific Hypothesis. The dissociations observed in this case compel a model in which sensory/motor modality and semantic domain jointly constrain the organization of object knowledge.

  4. When concepts lose their color: A case of object color knowledge impairment

    PubMed Central

    Stasenko, Alena; Garcea, Frank E.; Dombovy, Mary; Mahon, Bradford Z.

    2014-01-01

    Color is important in our daily interactions with objects, and plays a role in both low- and high-level visual processing. Previous neuropsychological studies have shown that color perception and object-color knowledge can doubly dissociate, and that both can dissociate from processing of object form. We present a case study of an individual who displayed an impairment for knowledge of the typical colors of objects, with preserved color perception and color naming. Our case also presented with a pattern of, if anything, worse performance for naming living items compared to nonliving things. The findings of the experimental investigation are evaluated in light of two theories of conceptual organization in the brain: the Sensory Functional Theory and the Domain-Specific Hypothesis. The dissociations observed in this case compel a model in which sensory/motor modality and semantic domain jointly constrain the organization of object knowledge. PMID:25058612

  5. Segregating animals in naturalistic surroundings: interaction of color distributions and mechanisms.

    PubMed

    Jansen, Michael; Giesel, Martin; Zaidi, Qasim

    2016-03-01

    Humans have been shown to rapidly detect animals in naturalistic scenes, but the role of color in this task is unclear. We first analyze the color information contained in a large number of images of salient and camouflaged animals in generic backgrounds. We found that color distributions of most animals and of their immediate backgrounds were oriented along other than the cardinal directions of color space. In addition, the maximum distances between animals and background distributions also tended to be along noncardinal directions, suggesting a role for higher-order cortical color mechanisms whose preferred axes are distributed widely in color space. We measured temporal thresholds for segmenting animal color distributions from background distributions in the absence of spatial cues. Combined over all observers and all images in our sample, thresholds for segmenting isoluminant projections of these distributions were lower than for segmenting the original distributions and considerably lower than for segmenting achromatic projections. Color information is thus likely to be useful in segregating animals in generic views, i.e., views not purposely chosen by the photographer to enhance the visibility of the animal. However, a comparison of thresholds with distances between distributions failed to reveal any advantage conferred by higher-order color mechanisms.

  6. Quantitative measurement of binocular color fusion limit for non-spectral colors.

    PubMed

    Jung, Yong Ju; Sohn, Hosik; Lee, Seong-il; Ro, Yong Man; Park, Hyun Wook

    2011-04-11

    Human perception becomes difficult in the event of binocular color fusion when the color difference presented for the left and right eyes exceeds a certain threshold value, known as the binocular color fusion limit. This paper discusses the binocular color fusion limit for non-spectral colors within the color gamut of a conventional LCD 3DTV. We performed experiments to measure the color fusion limit for eight chromaticity points sampled from the CIE 1976 chromaticity diagram. A total of 2480 trials were recorded for a single observer. By analyzing the results, the color fusion limit was quantified by ellipses in the chromaticity diagram. The semi-minor axis of the ellipses ranges from 0.0415 to 0.0923 in terms of the Euclidean distance in the u'v´ chromaticity diagram and the semi-major axis ranges from 0.0640 to 0.1560. These eight ellipses are drawn on the chromaticity diagram.

  7. Astronomy with the color blind

    NASA Astrophysics Data System (ADS)

    Smith, Donald A.; Melrose, Justyn

    2014-12-01

    The standard method to create dramatic color images in astrophotography is to record multiple black and white images, each with a different color filter in the optical path, and then tint each frame with a color appropriate to the corresponding filter. When combined, the resulting image conveys information about the sources of emission in the field, although one should be cautious in assuming that such an image shows what the subject would "really look like" if a person could see it without the aid of a telescope. The details of how the eye processes light have a significant impact on how such images should be understood, and the step from perception to interpretation is even more problematic when the viewer is color blind. We report here on an approach to manipulating stacked tricolor images that, while abandoning attempts to portray the color distribution "realistically," do result in enabling those suffering from deuteranomaly (the most common form of color blindness) to perceive color distinctions they would otherwise not be able to see.

  8. Color vision test

    MedlinePlus

    ... from birth) color vision problems: Achromatopsia -- complete color blindness , seeing only shades of gray Deuteranopia -- difficulty telling ... test - color; Ishihara color vision test Images Color blindness tests References Adams AJ, Verdon WA, Spivey BE. ...

  9. Design and imaging performance of achromatic diffractive-refractive x-ray and gamma-ray Fresnel lenses.

    PubMed

    Skinner, Gerald K

    2004-09-01

    Achromatic combinations of a diffractive phase Fresnel lens and a refractive correcting element have been proposed for x-ray and gamma-ray astronomy and for microlithography, but considerations of absorption often dictate that the refractive component be given a stepped profile, resulting in a double Fresnel lens. The imaging performance of corrected Fresnel lenses, with and without stepping, is investigated, and the trade-off between resolution and useful bandwidth in different circumstances is discussed. Provided that the focal ratio is large, correction lenses made from low atomic number materials can be used with x rays in the range of approximately 10-100 keV without stepping. The use of stepping extends the possibility of correction to higher-aperture systems, to energies as low as a few kilo electron volts, and to gamma rays of mega electron volt energy.

  10. A color-communication scheme for digital imagery

    USGS Publications Warehouse

    Acosta, Alex

    1987-01-01

    Color pictures generated from digital images are frequently used by geologists, foresters, range managers, and others. These color products are preferred over black and white pictures because the human eye is more sensitive to color differences than to various shades of gray. Color discrimination is a function of perception, and therefore colors in these color composites are generally described subjectively, which can lead to ambiguous color communication. Numerous color-coordinate systems are available that quantitively relate digital triplets representing amounts of red, free, and blue to the parameters of hue, saturation, and intensity perceived by the eye. Most of these systems implement a complex transformation of the primary colors to a color space that is hard to visualize, thus making it difficult to relate digital triplets to perception parameters. This paper presents a color-communcation scheme that relates colors on a color triangle to corresponding values of "hue" (H), "saturation" (S), and chromaticity coordinates (x,y,z). The scheme simplifies the relation between red, green, and blue (RGB) digital triplets and the color generated by these triplets. Some examples of the use of the color-communication scheme in digital image processing are presented.

  11. Generic conditions for suppressing the coherent synchrotron radiation induced emittance growth in a two-dipole achromat

    NASA Astrophysics Data System (ADS)

    Jiao, Yi; Cui, Xiaohao; Huang, Xiyang; Xu, Gang

    2014-06-01

    The effect of the coherent synchrotron radiation (CSR) becomes evident, and leads to increased beam energy spread and transverse emittance dilution, as both the emittance and bunch length of the electron beams are continuously pushed down in present and forthcoming high-brightness light sources and linear colliders. Suppressing this effect is important to preserve the expected machine performance. Methods of the R-matrix analysis and the Courant-Snyder formalism analysis have been proposed to evaluate and to suppress the emittance growth due to CSR in achromatic cells. In this paper a few important modifications are made on these two methods, which enable us to prove that these two methods are equivalent to each other. With the modified analysis, we obtain explicit and generic conditions of cancelling the CSR-driven emittance excitation in a single achromat consisting of two dipoles of arbitrary bending angles. In spite of the fact that the analysis constrains itself in a linear regime, based on the assumption that CSR-induced particle energy deviation is proportional to both θ and ρ1/3, with θ being the bending angle and ρ the bending radius, it is demonstrated through ELEGANT simulations that the conditions derived from this analysis are still effective in suppressing the emittance growth when a more detailed one-dimensional CSR model is considered. In addition, it illustrates that the emittance growth can be reduced to a lower level with the proposed conditions than with the other two approaches, such as matching the beam envelope to the CSR kick and setting the cell-to-cell betatron phase advance to an appropriate value.

  12. Color superconductivity

    SciTech Connect

    Wilczek, F.

    1997-09-22

    The asymptotic freedom of QCD suggests that at high density - where one forms a Fermi surface at very high momenta - weak coupling methods apply. These methods suggest that chiral symmetry is restored and that an instability toward color triplet condensation (color superconductivity) sets in. Here I attempt, using variational methods, to estimate these effects more precisely. Highlights include demonstration of a negative pressure in the uniform density chiral broken phase for any non-zero condensation, which we take as evidence for the philosophy of the MIT bag model; and demonstration that the color gap is substantial - several tens of MeV - even at modest densities. Since the superconductivity is in a pseudoscalar channel, parity is spontaneously broken.

  13. Color on emergency mapping

    NASA Astrophysics Data System (ADS)

    Jiang, Lili; Qi, Qingwen; Zhang, An

    2007-06-01

    There are so many emergency issues in our daily life. Such as typhoons, tsunamis, earthquake, fires, floods, epidemics, etc. These emergencies made people lose their lives and their belongings. Every day, every hour, even every minute people probably face the emergency, so how to handle it and how to decrease its hurt are the matters people care most. If we can map it exactly before or after the emergencies; it will be helpful to the emergency researchers and people who live in the emergency place. So , through the emergency map, before emergency is occurring we can predict the situation, such as when and where the emergency will be happen; where people can refuge, etc. After disaster, we can also easily assess the lost, discuss the cause and make the lost less. The primary effect of mapping is offering information to the people who care about the emergency and the researcher who want to study it. Mapping allows the viewers to get a spatial sense of hazard. It can also provide the clues to study the relationship of the phenomenon in emergency. Color, as the basic element of the map, it can simplify and clarify the phenomenon. Color can also affects the general perceptibility of the map, and elicits subjective reactions to the map. It is to say, structure, readability, and the reader's psychological reactions can be affected by the use of color.

  14. Color categories only affect post-perceptual processes when same- and different-category colors are equally discriminable.

    PubMed

    He, Xun; Witzel, Christoph; Forder, Lewis; Clifford, Alexandra; Franklin, Anna

    2014-04-01

    Prior claims that color categories affect color perception are confounded by inequalities in the color space used to equate same- and different-category colors. Here, we equate same- and different-category colors in the number of just-noticeable differences, and measure event-related potentials (ERPs) to these colors on a visual oddball task to establish if color categories affect perceptual or post-perceptual stages of processing. Category effects were found from 200 ms after color presentation, only in ERP components that reflect post-perceptual processes (e.g., N2, P3). The findings suggest that color categories affect post-perceptual processing, but do not affect the perceptual representation of color.

  15. Color transparency

    SciTech Connect

    Jennings, B.K.; Miller, G.A.

    1993-11-01

    The anomously large transmission of nucleons through a nucleus following a hard collision is explored. This effect, known as color transparency, is believed to be a prediction of QCD. The necessary conditions for its occurrence and the effects that must be included a realistic calculation are discussed.

  16. Color Sense

    ERIC Educational Resources Information Center

    Johnson, Heidi S. S.; Maki, Jennifer A.

    2009-01-01

    This article reports a study conducted by members of the WellU Academic Integration Subcommittee of The College of St. Scholastica's College's Healthy Campus Initiative plan whose purpose was to determine whether changing color in the classroom could have a measurable effect on students. One simple improvement a school can make in a classroom is…

  17. [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

  18. Importance of Achromatic Contrast in Short-Range Fruit Foraging of Primates

    PubMed Central

    Hiramatsu, Chihiro; Melin, Amanda D.; Aureli, Filippo; Schaffner, Colleen M.; Vorobyev, Misha; Matsumoto, Yoshifumi; Kawamura, Shoji

    2008-01-01

    Trichromatic primates have a ‘red-green’ chromatic channel in addition to luminance and ‘blue-yellow’ channels. It has been argued that the red-green channel evolved in primates as an adaptation for detecting reddish or yellowish objects, such as ripe fruits, against a background of foliage. However, foraging advantages to trichromatic primates remain unverified by behavioral observation of primates in their natural habitats. New World monkeys (platyrrhines) are an excellent model for this evaluation because of the highly polymorphic nature of their color vision due to allelic variation of the L-M opsin gene on the X chromosome. In this study we carried out field observations of a group of wild, frugivorous black-handed spider monkeys (Ateles geoffroyi frontatus, Gray 1842, Platyrrhini), consisting of both dichromats (n = 12) and trichromats (n = 9) in Santa Rosa National Park, Costa Rica. We determined the color vision types of individuals in this group by genotyping their L-M opsin and measured foraging efficiency of each individual for fruits located at a grasping distance. Contrary to the predicted advantage for trichromats, there was no significant difference between dichromats and trichromats in foraging efficiency and we found that the luminance contrast was the main determinant of the variation of foraging efficiency among red-green, blue-yellow and luminance contrasts. Our results suggest that luminance contrast can serve as an important cue in short-range foraging attempts despite other sensory cues that could be available. Additionally, the advantage of red-green color vision in primates may not be as salient as previously thought and needs to be evaluated in further field observations. PMID:18836576

  19. Grapheme-color synesthetes show peculiarities in their emotional brain: cortical and subcortical evidence from VBM analysis of 3D-T1 and DTI data.

    PubMed

    Melero, Helena; Peña-Melián, Ángel; Ríos-Lago, Marcos; Pajares, Gonzalo; Hernández-Tamames, Juan Antonio; Álvarez-Linera, Juan

    2013-06-01

    Grapheme-color synesthesia is a neurological phenomenon in which viewing achromatic letters/numbers leads to automatic and involuntary color experiences. In this study, voxel-based morphometry analyses were performed on T1 images and fractional anisotropy measures to examine the whole brain in associator grapheme-color synesthetes. These analyses provide new evidence of variations in emotional areas (both at the cortical and subcortical levels), findings that help understand the emotional component as a relevant aspect of the synesthetic experience. Additionally, this study replicates previous findings in the left intraparietal sulcus and, for the first time, reports the existence of anatomical differences in subcortical gray nuclei of developmental grapheme-color synesthetes, providing a link between acquired and developmental synesthesia. This empirical evidence, which goes beyond modality-specific areas, could lead to a better understanding of grapheme-color synesthesia as well as of other modalities of the phenomenon.

  20. Color difference threshold determination for acrylic denture base resins.

    PubMed

    Ren, Jiabao; Lin, Hong; Huang, Qingmei; Liang, Qifan; Zheng, Gang

    2015-01-01

    This study aimed to set evaluation indicators, i.e., perceptibility and acceptability color difference thresholds, of color stability for acrylic denture base resins for a spectrophotometric assessing method, which offered an alternative to the visual method described in ISO 20795-1:2013. A total of 291 disk specimens 50±1 mm in diameter and 0.5±0.1 mm thick were prepared (ISO 20795-1:2013) and processed through radiation tests in an accelerated aging chamber (ISO 7491:2000) for increasing times of 0 to 42 hours. Color alterations were measured with a spectrophotometer and evaluated using the CIE L*a*b* colorimetric system. Color differences were calculated through the CIEDE2000 color difference formula. Thirty-two dental professionals without color vision deficiencies completed perceptibility and acceptability assessments under controlled conditions in vitro. An S-curve fitting procedure was used to analyze the 50:50% perceptibility and acceptability thresholds. Furthermore, perceptibility and acceptability against the differences of the three color attributes, lightness, chroma, and hue, were also investigated. According to the S-curve fitting procedure, the 50:50% perceptibility threshold was 1.71ΔE00 (r(2)=0.88) and the 50:50% acceptability threshold was 4.00 ΔE00 (r(2)=0.89). Within the limitations of this study, 1.71/4.00 ΔE00 could be used as perceptibility/acceptability thresholds for acrylic denture base resins.

  1. Spectral Sensitivities and Color Signals in a Polymorphic Damselfly

    PubMed Central

    Huang, Shao-chang; Chiou, Tsyr-huei; Marshall, Justin; Reinhard, Judith

    2014-01-01

    Animal communication relies on conspicuous signals and compatible signal perception abilities. Good signal perception abilities are particularly important for polymorphic animals where mate choice can be a challenge. Behavioral studies suggest that polymorphic damselflies use their varying body colorations and/or color patterns as communication signal for mate choice and to control mating frequencies. However, solid evidence for this hypothesis combining physiological with spectral and behavioral data is scarce. We investigated this question in the Australian common blue tail damselfly, Ischnura heterosticta, which has pronounced female-limited polymorphism: andromorphs have a male-like blue coloration and gynomorphs display green/grey colors. We measured body color reflectance and investigated the visual capacities of each morph, showing that I. heterosticta have at least three types of photoreceptors sensitive to UV, blue, and green wavelength, and that this visual perception ability enables them to detect the spectral properties of the color signals emitted from the various color morphs in both males and females. We further demonstrate that different color morphs can be discriminated against each other and the vegetation based on color contrast. Finally, these findings were supported by field observations of natural mating pairs showing that mating partners are indeed chosen based on their body coloration. Our study provides the first comprehensive evidence for the function of body coloration on mate choice in polymorphic damselflies. PMID:24498233

  2. Colorful drying.

    PubMed

    Lakio, Satu; Heinämäki, Jyrki; Yliruusi, Jouko

    2010-03-01

    Drying is one of the standard unit operations in the pharmaceutical industry and it is important to become aware of the circumstances that dominate during the process. The purpose of this study was to test microcapsulated thermochromic pigments as heat indicators in a fluid bed drying process. The indicator powders were manually granulated with alpha-lactose monohydrate resulting in three particle-size groups. Also, pellets were coated with the indicator powders. The granules and pellets were fluidized in fluid bed dryer to observe the progress of the heat flow in the material and to study the heat indicator properties of the indicator materials. A tristimulus colorimeter was used to measure CIELAB color values. Color indicator for heat detection can be utilized to test if the heat-sensitive API would go through physical changes during the pharmaceutical drying process. Both the prepared granules and pellets can be used as heat indicator in fluid bed drying process. The colored heat indicators give an opportunity to learn new aspects of the process at real time and could be exploded, for example, for scaling-up studies.

  3. Nonlinear two-stage model for color discrimination.

    PubMed

    Inamura, Taisuke; Shioiri, Satoshi; Tsujimura, Sei-ichi; Yaguchi, Hirohisa

    2011-04-01

    We modified a two-stage model for color discrimination proposed in a previous study [Color Res. Appl.25, 105 (2000)]; in order to extend the model to wider conditions, we considered the conditions with luminance modulations in addition to color modulations. Using the modified model, we successfully predicted color discrimination data with test color changes along both the chromatic and luminance axes under a variety of background colors. Both qualitative and quantitative assessments in modeling showed that nonlinearity is required in both the cone and the cone-opponent stages to interpret adaptation effects of both color and luminance on color discrimination. This fact suggests that the nonlinear properties at each stage have different roles in color perception.

  4. Difference between highlight and object colors enhances glossiness.

    PubMed

    Hanada, Mitsuhiko

    2012-06-01

    The effect of highlight and object colors on perception of glossiness was examined. Ten participants rated glossiness of object images. The color coordinates of objects and highlights were varied while luminance of each pixel was unchanged. Four colors were used for objects and highlights. Objects were perceived as glossier when the highlight color was different from the object color than when they were the same. Objects with some unnatural combinations of highlight and object colors were perceived to be as glossy as those with natural color combinations. The results suggested that differences between highlight and object colors enhance perceived glossiness and that perceived glossiness does not depend on naturalness of color combination for highlights and objects.

  5. Introduction To Color Vision

    NASA Astrophysics Data System (ADS)

    Thorell, Lisa G.

    1983-08-01

    Several human cognitive studies have reported that color facilitates certain learning, memory and search tasks. Consideration of the color-opponent organization of human color vision and the spatial modulation transfer function for color suggests several simple sensory explanations.

  6. Why some colors appear more memorable than others: A model combining categories and particulars in color working memory.

    PubMed

    Bae, Gi-Yeul; Olkkonen, Maria; Allred, Sarah R; Flombaum, Jonathan I

    2015-08-01

    Categorization with basic color terms is an intuitive and universal aspect of color perception. Yet research on visual working memory capacity has largely assumed that only continuous estimates within color space are relevant to memory. As a result, the influence of color categories on working memory remains unknown. We propose a dual content model of color representation in which color matches to objects that are either present (perception) or absent (memory) integrate category representations along with estimates of specific values on a continuous scale ("particulars"). We develop and test the model through 4 experiments. In a first experiment pair, participants reproduce a color target, both with and without a delay, using a recently influential estimation paradigm. In a second experiment pair, we use standard methods in color perception to identify boundary and focal colors in the stimulus set. The main results are that responses drawn from working memory are significantly biased away from category boundaries and toward category centers. Importantly, the same pattern of results is present without a memory delay. The proposed dual content model parsimoniously explains these results, and it should replace prevailing single content models in studies of visual working memory. More broadly, the model and the results demonstrate how the main consequence of visual working memory maintenance is the amplification of category related biases and stimulus-specific variability that originate in perception.

  7. Brilliance, contrast, colorfulness, and the perceived volume of device color gamut

    NASA Astrophysics Data System (ADS)

    Heckaman, Rodney L.

    With the advent of digital video and cinema media technologies, much more is possible in achieving brighter and more vibrant colors, colors that transcend our experience. The challenge is in the realization of these possibilities in an industry rooted in 1950s technology where color gamut is represented with little or no insight into the way an observer perceives color as a complex mixture of the observer's intentions, desires, and interests. By today's standards, five perceptual attributes---brightness, lightness, colorfulness, chroma, and hue---are believed to be required for a complete specification. As a compelling case for such a representation, a display system is demonstrated that is capable of displaying color beyond the realm of object color, perceptually even beyond the spectrum locus of pure color. All this begs the question: Just what is meant by perceptual gamut? To this end, the attributes of perceptual gamut are identified through psychometric testing and the color appearance models CIELAB and CIECAM02. Then, by way of demonstration, these attributes were manipulated to test their application in wide gamut displays. In concert with these perceptual attributes and their manipulation, Ralph M. Evans' concept of brilliance as an attribute of perception that extends beyond the realm of everyday experience, and the theoretical studies of brilliance by Y. Nayatani, a method was developed for producing brighter, more colorful colors and deeper, darker colors with the aim of preserving object color perception---flesh tones in particular. The method was successfully demonstrated and tested in real images using psychophysical methods in the very real, practical application of expanding the gamut of sRGB into an emulation of the wide gamut, xvYCC encoding.

  8. Do focal colors look particularly "colorful"?

    PubMed

    Witzel, Christoph; Franklin, Anna

    2014-04-01

    If the most typical red, yellow, green, and blue were particularly colorful (i.e., saturated), they would "jump out to the eye." This would explain why even fundamentally different languages have distinct color terms for these focal colors, and why unique hues play a prominent role in subjective color appearance. In this study, the subjective saturation of 10 colors around each of these focal colors was measured through a pairwise matching task. Results show that subjective saturation changes systematically across hues in a way that is strongly correlated to the visual gamut, and exponentially related to sensitivity but not to focal colors.

  9. Color rendering of art paintings under CIE illuminants for normal and color deficient observers.

    PubMed

    Maciel Linhares, João Manuel; Araújo Pinto, Paulo Daniel; Cardoso Nascimento, Sérgio Miguel

    2009-07-01

    Color rendering indices are used to access the quality of lighting but, in addition to other well-known limitations, are not defined for color deficient observers. We evaluated the quality of lighting for normal and color deficient observers in the context of art paintings by estimating the number of colors they perceive when looking at the paintings. Hyperspectral data from 11 oil paintings were analyzed to compute the number of discernible colors when the paintings were assumed rendered under 55 CIE illuminants. Models of color perception for normal and color deficient observers were applied in the estimates. It was found that the number of discernible colors for normal and color deficient observers had low correlation with traditional color rendering indices and that some three-band illuminants, like HP4, were found to be good for most cases, except for tritanopes. These results suggest that it may be possible to obtain good lighting conditions for normal and color deficient observers with an appropriate choice of the light source.

  10. [True color accuracy in digital forensic photography].

    PubMed

    Ramsthaler, Frank; Birngruber, Christoph G; Kröll, Ann-Katrin; Kettner, Mattias; Verhoff, Marcel A

    2016-01-01

    Forensic photographs not only need to be unaltered and authentic and capture context-relevant images, along with certain minimum requirements for image sharpness and information density, but color accuracy also plays an important role, for instance, in the assessment of injuries or taphonomic stages, or in the identification and evaluation of traces from photos. The perception of color not only varies subjectively from person to person, but as a discrete property of an image, color in digital photos is also to a considerable extent influenced by technical factors such as lighting, acquisition settings, camera, and output medium (print, monitor). For these reasons, consistent color accuracy has so far been limited in digital photography. Because images usually contain a wealth of color information, especially for complex or composite colors or shades of color, and the wavelength-dependent sensitivity to factors such as light and shadow may vary between cameras, the usefulness of issuing general recommendations for camera capture settings is limited. Our results indicate that true image colors can best and most realistically be captured with the SpyderCheckr technical calibration tool for digital cameras tested in this study. Apart from aspects such as the simplicity and quickness of the calibration procedure, a further advantage of the tool is that the results are independent of the camera used and can also be used for the color management of output devices such as monitors and printers. The SpyderCheckr color-code patches allow true colors to be captured more realistically than with a manual white balance tool or an automatic flash. We therefore recommend that the use of a color management tool should be considered for the acquisition of all images that demand high true color accuracy (in particular in the setting of injury documentation).

  11. The Color of Safety: Ingroup Associated Colors make Beer Safer

    PubMed Central

    Loersch, Chris; Bartholow, Bruce D.

    2010-01-01

    Individuals display high levels of trust and express feelings of safety when interacting with social ingroup members. Here, we investigated whether cues related to ingroup membership would change perceptions of the safety of alcohol. Participants were exposed to images of beer in either a standard can or a can featuring the colors of their university (i.e., ‘fan cans’). We hypothesized that exposure to fan cans would change perceptions of the risks of beer drinking. Results showed that participants exposed to fan cans rated beer consumption as less dangerous (Experiment 1), were more likely to automatically activate safety-related mental content after unconscious perception of beer cues (Experiment 2), and viewed their ingroup’s party practices as less dangerous (Experiment 3). These results provide evidence that ingroup-associated colors can serve as a safety cue for alcohol, which may in theory perpetuate alcohol-related risk-taking, already a cause for concern on college and university campuses. PMID:21499547

  12. Dental color assessment through TTB exercises

    PubMed Central

    Draghici, R; Preoteasa, CT; Ţâncu, AMC; Preoteasa, E

    2016-01-01

    Abstract Aim.To verify the impact of taking the Toothguide Training Box (TTB) exercise in improving the individual ability to correctly determine dental color. Material and method.A prospective study was conducted on the 5th year dental students. The participants were required to carry out 3 distinct steps: visual color determination for sample tabs out of the 3DMaster shade guide, the TTB exercise and another color determination after training completion. Results.The sample included 60 students (19M/ 41F) with a mean age of 24, which made 360 color determinations of 6 shade tabs before and after TTB exercise. 32,5% (n=117) of the color determinations were incorrect in both moments, and the value was incorrectly determined just in 11% of them. Students found 3L1.5 and 3M2 colors as the hardest to determine. The results suggested that a single TTB training exercise did not have a high positive influence on the individual capacity to correctly determine the color for tabs out of the shade guide. Conclusions.While there is no evidence of an immediate positive impact of the TTB exercise in evaluating and determining different color variations for sample key elements, through repeat exercises, the individual perception can be improved and thus the correct determination of dental color and its correct codification can be increased. Abbreviations: TTB = Tooth Training Box, CIE = Commission internationale de l'éclairage, L = lightness, C = chroma, H = hue PMID:27974916

  13. Tenure and Promotion Experiences of Academic Librarians of Color

    ERIC Educational Resources Information Center

    Damasco, Ione T.; Hodges, Dracine

    2012-01-01

    This study broadly examines factors impacting work-life experiences of library faculty of color within the framework of tenure policies and processes. An online survey was sent out to academic librarians of color to gauge perceptions of tenure and promotion policies and processes, professional activities and productivity, organizational climate…

  14. Josef Alber's "Interaction of Color": From Print to Interactive Multimedia.

    ERIC Educational Resources Information Center

    Whiteley, Jerry; Roberts, Joseph

    1990-01-01

    Describes the development of interactive, multimedia courseware based on Josef Alber's book, "Interaction of Color." Alber's ideas and teachings on the perceptions of color are explained, and steps involving computer graphics, hardware, and software that resulted in the use of CD-ROM and videodisc with an Apple Macintosh II are detailed.…

  15. Full-color autostereoscopic video display system using computer-generated synthetic phase holograms

    NASA Astrophysics Data System (ADS)

    Choi, Kyongsik; Kim, Hwi; Lee, Byoungho

    2005-03-01

    A full-color auto-stereoscopic video display system has been introduced and developed using only a single phase-only spatial light modulator, a simple projection lens module, and three laser diode sources with the wavelengths of 635nm (red), 532nm (green), and 473nm (blue). Full-color stereoscopic input video frames are separated by each red, green, and blue component with respect to each stereo eye view for a 3D image frame. Each hologram is then optimized by a modified iterative Fresnel transform algorithm method, for the reconstruction of each gray-level quantized stereo image without color dispersion. To solve the color dispersion problem we applied scaling constraints and phase-leveling techniques for each hologram. Then the optimized holograms are synthesized with direction-multiplexed holograms and modulated by a single phase-type spatial light modulator. The modulated signals are Fourier-transformed by an achromatic lens and redirected to each viewer's eye for the reconstruction of the composed full-color auto-stereoscopic 3D display. Experimentally, we demonstrated that the designed computer-generated holograms were able to generate full-color stereoscopic 3D video images without glasses.

  16. The locus of color sensation: Cortical color loss and the chromatic visual evoked potential

    PubMed Central

    Crognale, Michael A.; Duncan, Chad S.; Shoenhard, Hannah; Peterson, Dwight J.; Berryhill, Marian E.

    2013-01-01

    Color losses of central origin (cerebral achromatopsia and dyschromatopsia) can result from cortical damage and are most commonly associated with stroke. Such cases have the potential to provide useful information regarding the loci of the generation of the percept of color. One available tool to examine this issue is the chromatic visual evoked potential (cVEP). The cVEP has been used successfully to objectively quantify losses in color vision capacity in both congenital and acquired deficiencies of retinal origin but has not yet been applied to cases of color losses of cortical origin. In addition, it is not known with certainty which cortical sites are responsible for the generation of the cVEP waveform components. Here we report psychophysical and electrophysiological examination of a patient with color deficits resulting from a bilateral cerebral infarct in the ventral occipitotemporal region. Although this patient demonstrated pronounced color losses of a general nature, the waveform of the cVEP remains unaffected. Contrast response functions of the cVEP are also normal for this patient. The results suggest that the percept of color arises after the origin of the cVEP and that normal activity in those areas that give rise to the characteristic negative wave of the cVEP are not sufficient to provide for the normal sensation of color. PMID:23986535

  17. Color Reproduction System Based on Color Appearance Model and Gamut Mapping

    DTIC Science & Technology

    2000-07-01

    and Gamut Mapping DISTRIBUTION: Approved for public release, distribution unlimited This paper is part of the following report: TITLE: Input/Output...report: ADP011333 thru ADP011362 UNCLASSIFIED Color reproduction system based on color appearance model and gamut mapping Fang-Hsuan Cheng, Chih-Yuan...perception is usually different. Basically, the influence factors are device calibration and characterization, viewing condition, device gamut and human

  18. Social Work Students' Perceptions of Team-Based Learning

    ERIC Educational Resources Information Center

    Macke, Caroline; Taylor, Jessica Averitt; Taylor, James E.; Tapp, Karen; Canfield, James

    2015-01-01

    This study sought to examine social work students' perceptions of Team-Based Learning (N = 154). Aside from looking at overall student perceptions, comparative analyses examined differences in perceptions between BSW and MSW students, and between Caucasian students and students of color. Findings for the overall sample revealed favorable…

  19. Color-weak compensation using local affine isometry based on discrimination threshold matching.

    PubMed

    Mochizuki, Rika; Kojima, Takanori; Lenz, Reiner; Chao, Jinhui

    2015-11-01

    We develop algorithms for color-weak compensation and color-weak simulation based on Riemannian geometry models of color spaces. The objective function introduced measures the match of color discrimination thresholds of average normal observers and a color-weak observer. The developed matching process makes use of local affine maps between color spaces of color-normal and color-weak observers. The method can be used to generate displays of images that provide color-normal and color-weak observers with a similar color difference experience. It can also be used to simulate the perception of a color-weak observer for color-normal observers. We also introduce a new database of measurements of color discrimination threshold data for color-normal and color-weak observers obtained at different lightness levels in CIELUV space. The compensation methods include compensations of chromaticity using local affine maps between chromaticity planes of color-normal and color-weak observers, and one-dimensional (1D) compensation on lightness. We describe how to determine correspondences between the origins of local coordinates in color spaces of color-normal and color-weak observers using a neighborhood expansion method. After matching the origins of the two coordinate systems, a local affine map is estimated by solving a nonlinear equation, or singular-value-decomposition (SVD). We apply the methods to natural images and evaluate their performance using the semantic differential (SD) method.

  20. Color obsessions and phobias in autism spectrum disorders: the case of J.G.

    PubMed

    Ludlow, Amanda K; Heaton, Pamela; Hill, Elisabeth; Franklin, Anna

    2014-06-01

    The current study is the first investigation of color 'obsessions' and 'phobias' in ASD. We investigate the color perception and cognition of J.G., a boy with ASD who has a strong obsession with blue, and a strong phobia of other colors. J.G.'s performance on a series of color tasks (color-entity association; chromatic discrimination; color classification) is compared to 13 children with and without autism who do not have color obsessions or phobias. The findings lead to the formalization of two hypotheses: (i) color obsessions and phobias in individuals with ASD are related to an unusually strong ability to associate colors with entities; (ii) color obsessions are related to hyposensitivity, and color phobias to hypersensitivity, in the affected regions of color space.

  1. Ebony and Ivory: Relationship between African American Young Women's Skin Color and Ratings of Self and Peers

    ERIC Educational Resources Information Center

    Nassar-McMillan, Sylvia; McFall-Roberts, Ebuni; Flowers, Claudia; Garrett, Michael T.

    2006-01-01

    Many individuals face discrimination because of their skin color; however, skin color of African American young adults has not been studied in detail. This study examines relationships between skin color and perceptions among African American college women. The study yielded a positive correlation between personal values and self-rated skin color

  2. Color Relationalism and Relativism.

    PubMed

    Byrne, Alex; Hilbert, David R

    2017-01-01

    This paper critically examines color relationalism and color relativism, two theories of color that are allegedly supported by variation in normal human color vision. We mostly discuss color relationalism, defended at length in Jonathan Cohen's The Red and the Real, and argue that the theory has insuperable problems.

  3. Primary Theme Club. Colors.

    ERIC Educational Resources Information Center

    Walmsley, Bonnie Brown; Camp, Anne-Marie

    1997-01-01

    Presents a cross-curricular theme unit on colors that includes a pullout poster and a resource list. Social studies activities highlight flags of the world. Science activities teach about colors of animals and the science of color. Language arts activities describe colorful language. Mathematics activities involve sorting and graphing colors. (SM)

  4. Activities: Some Colorful Mathematics.

    ERIC Educational Resources Information Center

    DeTemple, Duane W.; Walker, Dean A.

    1996-01-01

    Describes three activities in discrete mathematics that involve coloring geometric objects: counting colored regions of overlapping simple closed curves, counting colored triangulations of polygons, and determining the number of colors required to paint the plane so that no two points one inch apart are the same color. (MKR)

  5. Cognitive components of color vision in honey bees: how conditioning variables modulate color learning and discrimination.

    PubMed

    Avarguès-Weber, Aurore; Giurfa, Martin

    2014-06-01

    Since the demonstration of color vision in honey bees 100 years ago by Karl von Frisch, appetitive conditioning to color targets has been used as the principal way to access behavioral aspects of bee color vision. Yet, analyses on how conditioning parameters affect color perception remained scarce. Conclusions on bee color vision have often been made without referring them to the experimental context in which they were obtained, and thus presented as absolute facts instead of realizing that subtle variations in conditioning procedures might yield different results. Here, we review evidence showing that color learning and discrimination in bees are not governed by immutable properties of their visual system, but depend on how the insects are trained and thus learn a task. The use of absolute or differential conditioning protocols, the presence of aversive reinforcement in differential conditioning and the degrees of freedom of motor components determine dramatic variations in color discrimination. We, thus, suggest top-down attentional modulation of color vision to explain the changes in color learning and discrimination reviewed here. We discuss the possible neural mechanisms of this modulation and conclude that color vision experiments require a careful consideration of how training parameters shape behavioral responses.

  6. Color vision and color formation in dragonflies.

    PubMed

    Futahashi, Ryo

    2016-10-01

    Dragonflies including damselflies are colorful and large-eyed insects, which show remarkable sexual dimorphism, color transition, and color polymorphism. Recent comprehensive visual transcriptomics has unveiled an extraordinary diversity of opsin genes within the lineage of dragonflies. These opsin genes are differentially expressed between aquatic larvae and terrestrial adults, as well as between dorsal and ventral regions of adult compound eyes. Recent topics of color formation in dragonflies are also outlined. Non-iridescent blue color is caused by coherent light scattering from the quasiordered nanostructures, whereas iridescent color is produced by multilayer structures. Wrinkles or wax crystals sometimes enhances multilayer structural colors. Sex-specific and stage-specific color differences in red dragonflies is attributed to redox states of ommochrome pigments.

  7. Urine - abnormal color

    MedlinePlus

    ... medlineplus.gov/ency/article/003139.htm Urine - abnormal color To use the sharing features on this page, please enable JavaScript. The usual color of urine is straw-yellow. Abnormally colored urine ...

  8. Tooth - abnormal colors

    MedlinePlus

    ... medlineplus.gov/ency/article/003065.htm Tooth - abnormal colors To use the sharing features on this page, please enable JavaScript. Abnormal tooth color is any color other than white to yellowish- ...

  9. LED Color Characteristics

    SciTech Connect

    2012-01-01

    Color quality is an important consideration when evaluating LED-based products for general illumination. This fact sheet reviews the basics regarding light and color and summarizes the most important color issues related to white-light LED systems.

  10. Color Blindness Simulations

    MedlinePlus

    ... Coordinator Color blindness Simulations Normal Color Vision Deuteranopia Color blindness marked by confusion of purplish red and green Tritanopia A dichromatism in which the spectrum is seen in tones of red and green. ...

  11. Neural locus of color afterimages.

    PubMed

    Zaidi, Qasim; Ennis, Robert; Cao, Dingcai; Lee, Barry

    2012-02-07

    After fixating on a colored pattern, observers see a similar pattern in complementary colors when the stimulus is removed [1-6]. Afterimages were important in disproving the theory that visual rays emanate from the eye, in demonstrating interocular interactions, and in revealing the independence of binocular vision from eye movements. Afterimages also prove invaluable in exploring selective attention, filling in, and consciousness. Proposed physiological mechanisms for color afterimages range from bleaching of cone photopigments to cortical adaptation [4-9], but direct neural measurements have not been reported. We introduce a time-varying method for evoking afterimages, which provides precise measurements of adaptation and a direct link between visual percepts and neural responses [10]. We then use in vivo electrophysiological recordings to show that all three classes of primate retinal ganglion cells exhibit subtractive adaptation to prolonged stimuli, with much slower time constants than those expected of photoreceptors. At the cessation of the stimulus, ganglion cells generate rebound responses that can provide afterimage signals for later neurons. Our results indicate that afterimage signals are generated in the retina but may be modified like other retinal signals by cortical processes, so that evidence presented for cortical generation of color afterimages is explainable by spatiotemporal factors that modify all signals.

  12. A low cost color visual stimulator for fMRI.

    PubMed

    Rogers, Bill; Shih, Yen-Yu I; Garza, Bryan De La; Harrison, Joseph M; Roby, John; Duong, Timothy Q

    2012-03-15

    This low cost visual stimulator was developed for use in small animal imaging. The stimulator uses a single tri-color LED for each eye and can output red, green, or blue light or any combination of the three. When all three LED colors are illuminated at the same time achromatic light is the output. The stimulator is almost entirely implemented in software with only minimal electronics. The LEDs are controlled via the parallel port of a desktop computer. Flicker frequency, wavelength, intensity and waveform shape are under software control. The LEDs are coupled to fiber optic cables which run into the MRI scanner room leaving the LEDs and the power source in the control room. Calibration with a radiometer shows the light output to be very linear from zero to full intensity. The stimulator was used in fMRI visual stimulation studies performed on Sprague Dawley rats with an 11.7Tesla magnet. As the stimulator is software driven, modifications to accommodate other protocols and extensions for new functionality can be readily incorporated. With this in mind, the visual stimulator circuit diagram and software including source code are available upon request.

  13. Automatic Palette Identification of Colored Graphics

    NASA Astrophysics Data System (ADS)

    Lacroix, Vinciane

    The median-shift, a new clustering algorithm, is proposed to automatically identify the palette of colored graphics, a pre-requisite for graphics vectorization. The median-shift is an iterative process which shifts each data point to the "median" point of its neighborhood defined thanks to a distance measure and a maximum radius, the only parameter of the method. The process is viewed as a graph transformation which converges to a set of clusters made of one or several connected vertices. As the palette identification depends on color perception, the clustering is performed in the L*a*b* feature space. As pixels located on edges are made of mixed colors not expected to be part of the palette, they are removed from the initial data set by an automatic pre-processing. Results are shown on scanned maps and on the Macbeth color chart and compared to well established methods.

  14. Variations in normal color vision. VII. Relationships between color naming and hue scaling.

    PubMed

    Emery, Kara J; Volbrecht, Vicki J; Peterzell, David H; Webster, Michael A

    2017-01-05

    A longstanding and unresolved question is how observers construct a discrete set of color categories to partition and label the continuous variations in light spectra, and how these categories might reflect the neural representation of color. We explored the properties of color naming and its relationship to color appearance by analyzing individual differences in color-naming and hue-scaling patterns, using factor analysis of individual differences to identify separate and shared processes underlying hue naming (labeling) and hue scaling (color appearance). Observers labeled the hues of 36 stimuli spanning different angles in cone-opponent space, using a set of eight terms corresponding to primary (red, green, blue, yellow) or binary (orange, purple, blue-green, yellow-green) hues. The boundaries defining different terms varied mostly independently, reflecting the influence of at least seven to eight factors. This finding is inconsistent with conventional color-opponent models in which all colors derive from the relative responses of underlying red-green and blue-yellow dimensions. Instead, color categories may reflect qualitatively distinct attributes that are free to vary with the specific spectral stimuli they label. Inter-observer differences in color naming were large and systematic, and we examined whether these differences were associated with differences in color appearance by comparing the hue naming to color percepts assessed by hue scaling measured in the same observers (from Emery et al., 2017). Variability in both tasks again depended on multiple (7 or 8) factors, with some Varimax-rotated factors specific to hue naming or hue scaling, but others common to corresponding stimuli for both judgments. The latter suggests that at least some of the differences in how individuals name or categorize color are related to differences in how the stimuli are perceived.

  15. Advances in color science: from retina to behavior.

    PubMed

    Conway, Bevil R; Chatterjee, Soumya; Field, Greg D; Horwitz, Gregory D; Johnson, Elizabeth N; Koida, Kowa; Mancuso, Katherine

    2010-11-10

    Color has become a premier model system for understanding how information is processed by neural circuits, and for investigating the relationships among genes, neural circuits, and perception. Both the physical stimulus for color and the perceptual output experienced as color are quite well characterized, but the neural mechanisms that underlie the transformation from stimulus to perception are incompletely understood. The past several years have seen important scientific and technical advances that are changing our understanding of these mechanisms. Here, and in the accompanying minisymposium, we review the latest findings and hypotheses regarding color computations in the retina, primary visual cortex, and higher-order visual areas, focusing on non-human primates, a model of human color vision.

  16. Rapid and implicit effects of color category on visual search

    NASA Astrophysics Data System (ADS)

    Yokoi, Kenji; Watanabe, Katsumi; Saida, Shinya

    2012-07-01

    Many studies suggest that the color category influences visual perception. It is also well known that oculomotor control and visual attention are closely linked. In order to clarify temporal characteristics of color categorization, we investigated eye movements during color visual search. Eight color disks were presented briefly for 20-320 ms, and the subject was instructed to gaze at a target shown prior to the trial. We found that the color category of the target modulated eye movements significantly when the stimulus was displayed for more than 40 ms and the categorization could be completed within 80 ms. With the 20 ms presentation, the search performance was at a chance level, however, the first saccadic latency suggested that the color category had an effect on visual attention. These results suggest that color categorization affects the guidance of visual attention rapidly and implicitly.

  17. New Windows based Color Morphological Operators for Biomedical Image Processing

    NASA Astrophysics Data System (ADS)

    Pastore, Juan; Bouchet, Agustina; Brun, Marcel; Ballarin, Virginia

    2016-04-01

    Morphological image processing is well known as an efficient methodology for image processing and computer vision. With the wide use of color in many areas, the interest on the color perception and processing has been growing rapidly. Many models have been proposed to extend morphological operators to the field of color images, dealing with some new problems not present previously in the binary and gray level contexts. These solutions usually deal with the lattice structure of the color space, or provide it with total orders, to be able to define basic operators with required properties. In this work we propose a new locally defined ordering, in the context of window based morphological operators, for the definition of erosions-like and dilation-like operators, which provides the same desired properties expected from color morphology, avoiding some of the drawbacks of the prior approaches. Experimental results show that the proposed color operators can be efficiently used for color image processing.

  18. Color signals through dorsal and ventral visual pathways

    PubMed Central

    Conway, Bevil R.

    2014-01-01

    Explanations for color phenomena are often sought in the retina, LGN and V1, yet it is becoming increasingly clear that a complete account will take us further along the visual-processing pathway. Working out which areas are involved is not trivial. Responses to S-cone activation are often assumed to indicate that an area or neuron is involved in color perception. However, work tracing S-cone signals into extrastriate cortex has challenged this assumption: S-cone responses have been found in brain regions, such as MT, not thought to play a major role in color perception. Here we review the processing of S-cone signals across cortex and present original data on S-cone responses measured with fMRI in alert macaque, focusing on one area in which S-cone signals seem likely to contribute to color (V4/posterior inferior temporal cortex), and on one area in which S signals are unlikely to play a role in color (MT). We advance a hypothesis that the S-cone signals in color-computing areas are required to achieve a balanced neural representation of perceptual color space, while the S-cone signals in non-color-areas provide a cue to illumination (not luminance) and confer sensitivity to the chromatic contrast generated by natural daylight (shadows, illuminated by ambient sky, surrounded by direct sunlight). This sensitivity would facilitate the extraction of shape-from-shadow signals to benefit global scene analysis and motion perception. PMID:24103417

  19. Diffractive parameric colors.

    PubMed

    Orava, Joni; Heikkila, Noora; Jaaskelainen, Timo; Parkkinen, Jussi

    2008-12-01

    A method of producing inkless parameric color pairs is studied. In this method, colors are formed additively using diffraction gratings with differing grating periods as primary colors. Gratings with different grating periods reflect different spectral radiance peaks of a fluorescent lamp to the desired viewing angle, according to the grating equation. Four spectral peaks of a 4000 K fluorescent lamp--red, green, cyan, and blue-are used as the primary colors. The colors are mixed additively by fixing the relative areas of different grating periods inside a pixel. With four primary colors it is possible to mix certain colors with different triplets of primary colors. Thus, it is theoretically possible to produce metameric colors. In this study, three parameric color pairs are fabricated using electron beam lithography, electroplating, and hot embossing. The radiance spectra of the color pairs are measured by spectroradiometer from hot-embossed plastic samples. The CIELAB DeltaE(ab) and CIEDE2000 color differences between radiance spectra of the color pairs are calculated. The CIEDE2000 color differences of color pairs are between 2.6 and 7.2 units in reference viewing conditions. The effects of viewing angle and different light sources are also evaluated. It is found that both the viewing angle and the light source have very strong influences on the color differences of the color pairs.

  20. Lonophore-based lithium ion film optode realizing multiple color variations utilizing digital color analysis.

    PubMed

    Suzuki, Koji; Hirayama, Etsuko; Sugiyama, Tsunemi; Yasuda, Keiko; Okabe, Hiroaki; Citterio, Daniel

    2002-11-15

    Digital color analysis (DCA), utilizing colors themselves or digital information of colors, can not only be applied to various quantitative analysis using chromaticity coordinates but can also be used to develop suitable sensors for visual colorimetry based on the characteristics of human visual perception by virtual simulations based on digital color information. To achieve a clear visual color variation for lithium ion determination, we designed and prepared a color-changeable film sensor (film optode) by the use of two kinds of lipophilic dyes, KD-C4 and KD-M11, whose colors and pKa values are different. This film sensor is a plasticized PVC membrane containing the mixture of two kinds of dyes with the lithium ionophore TTD14C4 and the lipophilic anionic additive tetrakis-[3,5-bis(trisfluoromethyl)phenyl]borate sodium salt dihydrate. The simulation of the color variation using the mixed dyes was evaluated by plotting the values on a uniform chromaticity scale diagram in a*b* coordinates, after converting the tristimulus values of each dye into its L*a*b* values. When the lithium ion concentration was actually determined by the PVC film optode containing the mixed dyes whose molecular ratio of KD-C4/KD-Ml 1 was 3:1, the hues of red --> orange --> yellow --> green --> blue could be realized in the range of 10(-6)-1 M. This observed color variation was similar to the result of the virtual simulation based on DCA.

  1. Uniform color space based on color matching

    NASA Astrophysics Data System (ADS)

    Liao, Shih-Fang; Yang, Tsung-Hsun; Lee, Cheng-Chung

    2007-09-01

    This research intends to explore with a uniform color space based on the CIE 1931 x-y chromatic coordinate system. The goal is to improve the non-uniformity of the CIE 1931 x-y chromaticity diagram such as to approach the human color sensation as possible; however, its simple methodology still can be kept. In spite of the existence of various kinds of the uniform color coordinate systems built up early (CIE u'-v', CIE Lab, CIE LUV, etc.), the establishment of a genuine uniform color space is actually still an important work both for the basic research in color science and the practical applications of colorimetry, especially for recent growing request in illumination engineering and in display technology. In this study, the MacAdam ellipses and the Munsell color chips are utilized for the comparison with the human color sensation. One specific linear transformation matrix is found for the CIE 1931 color matching functions (see manuscript) to become the novel uniform ones. With the aid of the optimization method, the transformation matrix can be easily discovered and makes the 25 MacAdam ellipses are similar to each other in the novel uniform color space. On the other hand, the perfectiveness of the equal-hue curves and the equal-chroma contours from the Mnusell color chips evaluates for the best optimization conditions among several different definitions for the similarity of all the MacAdam ellipses. Finally, the color difference between any two colors can be simply measured by the Euclidean distance in the novel uniform color space and is still fitted to the human color sensation.

  2. Color identification testing device

    NASA Technical Reports Server (NTRS)

    Brawner, E. L.; Martin, R.; Pate, W.

    1970-01-01

    Testing device, which determines ability of a technician to identify color-coded electric wires, is superior to standard color blindness tests. It tests speed of wire selection, detects partial color blindness, allows rapid testing, and may be administered by a color blind person.

  3. Color Me Understood.

    ERIC Educational Resources Information Center

    Harris, Judy J.

    2000-01-01

    Describes the "color system" as a way of grouping children into different personality types based on a certain color: orange, blue, green, and gold. Lists stress producers for specific color people. Asserts that, through making groups of different colors, children begin to see the various specialties others can bring to the group and learn to…

  4. Digital Color Image Restoration

    DTIC Science & Technology

    1975-08-01

    color image recording system is derived and the equations representing the model and the equations of colorimetry are expressed in matrix form. Computer ... algorithms are derived which correct color errors introduced by imperfections in the color recording system. The sources of color error which are

  5. Perceptual evaluation of colorized nighttime imagery

    NASA Astrophysics Data System (ADS)

    Toet, Alexander; de Jong, Michael J.; Hogervorst, Maarten A.; Hooge, Ignace T. C.

    2014-02-01

    We recently presented a color transform that produces fused nighttime imagery with a realistic color appearance (Hogervorst and Toet, 2010, Information Fusion, 11-2, 69-77). To assess the practical value of this transform we performed two experiments in which we compared human scene recognition for monochrome intensified (II) and longwave infrared (IR) imagery, and color daylight (REF) and fused multispectral (CF) imagery. First we investigated the amount of detail observers can perceive in a short time span (the gist of the scene). Participants watched brief image presentations and provided a full report of what they had seen. Our results show that REF and CF imagery yielded the highest precision and recall measures, while both II and IR imagery yielded significantly lower values. This suggests that observers have more difficulty extracting information from monochrome than from color imagery. Next, we measured eye fixations of participants who freely explored the images. Although the overall fixation behavior was similar across image modalities, the order in which certain details were fixated varied. Persons and vehicles were typically fixated first in REF, CF and IR imagery, while they were fixated later in II imagery. In some cases, color remapping II imagery and fusion with IR imagery restored the fixation order of these image details. We conclude that color remapping can yield enhanced scene perception compared to conventional monochrome nighttime imagery, and may be deployed to tune multispectral image representation such that the resulting fixation behavior resembles the fixation behavior for daylight color imagery.

  6. The Interface Theory of Perception.

    PubMed

    Hoffman, Donald D; Singh, Manish; Prakash, Chetan

    2015-12-01

    Perception is a product of evolution. Our perceptual systems, like our limbs and livers, have been shaped by natural selection. The effects of selection on perception can be studied using evolutionary games and genetic algorithms. To this end, we define and classify perceptual strategies and allow them to compete in evolutionary games in a variety of worlds with a variety of fitness functions. We find that veridical perceptions--strategies tuned to the true structure of the world--are routinely dominated by nonveridical strategies tuned to fitness. Veridical perceptions escape extinction only if fitness varies monotonically with truth. Thus, a perceptual strategy favored by selection is best thought of not as a window on truth but as akin to a windows interface of a PC. Just as the color and shape of an icon for a text file do not entail that the text file itself has a color or shape, so also our perceptions of space-time and objects do not entail (by the Invention of Space-Time Theorem) that objective reality has the structure of space-time and objects. An interface serves to guide useful actions, not to resemble truth. Indeed, an interface hides the truth; for someone editing a paper or photo, seeing transistors and firmware is an irrelevant hindrance. For the perceptions of H. sapiens, space-time is the desktop and physical objects are the icons. Our perceptions of space-time and objects have been shaped by natural selection to hide the truth and guide adaptive behaviors. Perception is an adaptive interface.

  7. Quantifying nonhomogeneous colors in agricultural materials. Part II: comparison of machine vision and sensory panel evaluations.

    PubMed

    Balaban, M O; Aparicio, J; Zotarelli, M; Sims, C

    2008-11-01

    The average colors of mangos and apples were measured using machine vision. A method to quantify the perception of nonhomogeneous colors by sensory panelists was developed. Three colors out of several reference colors and their perceived percentage of the total sample area were selected by untrained panelists. Differences between the average colors perceived by panelists and those from the machine vision were reported as DeltaE values (color difference error). Effects of nonhomogeneity of color, and using real samples or their images in the sensory panels on DeltaE were evaluated. In general, samples with more nonuniform colors had higher DeltaE values, suggesting that panelists had more difficulty in evaluating more nonhomogeneous colors. There was no significant difference in DeltaE values between the real fruits and their screen image, therefore images can be used to evaluate color instead of the real samples.

  8. Preferred memory color difference between the deuteranomalous and normal color vision

    NASA Astrophysics Data System (ADS)

    Baek, YeSeul; Kwak, Youngshin; Woo, Sungjoo; Park, Chongwook

    2015-01-01

    The goal of this study is to evaluate the difference of the preferred hues of familiar objects between the color deficient observer and the normal observer. Thirteen test color images were chosen covering fruit colors, natural scene and human faces. It contained red, yellow, green, blue, purple and skin color. Two color deficient observer (deuteranomal) and two normal observers were participated in this experiment. They controlled the YCC hue of the objects in the images to obtain the most preferred and the most natural image. The selected images were analyzed using CIELAB values of each pixel. Data analysis results showed that in the case of naturalness, both groups selected the similar hues for the most of image, while, in the case of preference, the color deficient observer preferred more reddish or more greenish images. Since the deuteranomalous observer has relatively week perception for red and green region, they may prefer more reddish or greenish color. The color difference between natural hue and preferred hue of deuteranomal observer is bigger than those of normal observer.

  9. Color signal integration for color discrimination along a long-range apparent motion trajectory.

    PubMed

    Nagai, Takehiro; Kimura, Hiroto; Nakauchi, Shigeki

    2013-01-01

    In contrast to the classical view that fundamental visual attributes such as color and motion are independently processed in the visual system (e.g. Livingstone and Hubel, 1987; Marr, 1982), recent studies have revealed various forms of cross-attribute interactions, such as averaging of color appearance along the motion trajectory of an object (Nishida et al., 2007). In this study, we investigated whether such color signal integration along a motion trajectory can be induced only by motion mechanisms having large receptive fields, without simple integration within direction-selective neurons with small receptive fields, like those in V1. The stimulus consisted of discs with long-range apparent motion along a circular trajectory. The stimulus onset asynchrony (SOA) between disc presentations controlled the strength of the apparent motion perception. We measured observers' sensitivity in detecting color modulation on the discs. The results showed that the measured sensitivity was lowest at SOAs corresponding to the strongest motion perception. This can be interpreted as follows: color signals were integrated along an apparent motion path, and this integration reduced chromatic sensitivity by averaging color signals. Another experiment that controlled apparent motion perception in a different way also supported this idea. However, this integration effect seemed to be linked to responses of motion detectors for the apparent motion stimuli, not directly to perceptual motion representation in the visual system. These results suggest that the human visual system handles color information from retinal inputs regarding moving objects based not only on a retinotopic coordinate but also on object-based coordinates, even when the moving object yields only long-range apparent motion.

  10. Motion Alters Color Appearance

    PubMed Central

    Hong, Sang-Wook; Kang, Min-Suk

    2016-01-01

    Chromatic induction compellingly demonstrates that chromatic context as well as spectral lights reflected from an object determines its color appearance. Here, we show that when one colored object moves around an identical stationary object, the perceived saturation of the stationary object decreases dramatically whereas the saturation of the moving object increases. These color appearance shifts in the opposite directions suggest that normalization induced by the object’s motion may mediate the shift in color appearance. We ruled out other plausible alternatives such as local adaptation, attention, and transient neural responses that could explain the color shift without assuming interaction between color and motion processing. These results demonstrate that the motion of an object affects both its own color appearance and the color appearance of a nearby object, suggesting a tight coupling between color and motion processing. PMID:27824098

  11. Resolution for color photography

    NASA Astrophysics Data System (ADS)

    Hubel, Paul M.; Bautsch, Markus

    2006-02-01

    Although it is well known that luminance resolution is most important, the ability to accurately render colored details, color textures, and colored fabrics cannot be overlooked. This includes the ability to accurately render single-pixel color details as well as avoiding color aliasing. All consumer digital cameras on the market today record in color and the scenes people are photographing are usually color. Yet almost all resolution measurements made on color cameras are done using a black and white target. In this paper we present several methods for measuring and quantifying color resolution. The first method, detailed in a previous publication, uses a slanted-edge target of two colored surfaces in place of the standard black and white edge pattern. The second method employs the standard black and white targets recommended in the ISO standard, but records these onto the camera through colored filters thus giving modulation between black and one particular color component; red, green, and blue color separation filters are used in this study. The third method, conducted at Stiftung Warentest, an independent consumer organization of Germany, uses a whitelight interferometer to generate fringe pattern targets of varying color and spatial frequency.

  12. Magnetoencephalography reveals early activation of V4 in grapheme-color synesthesia.

    PubMed

    Brang, D; Hubbard, E M; Coulson, S; Huang, M; Ramachandran, V S

    2010-10-15

    Grapheme-color synesthesia is a neurological phenomenon in which letters and numbers (graphemes) consistently evoke particular colors (e.g. A may be experienced as red). The cross-activation theory proposes that synesthesia arises as a result of cross-activation between posterior temporal grapheme areas (PTGA) and color processing area V4, while the disinhibited feedback theory proposes that synesthesia arises from disinhibition of pre-existing feedback connections. Here we used magnetoencephalography (MEG) to test whether V4 and PTGA activate nearly simultaneously, as predicted by the cross-activation theory, or whether V4 activation occurs only after the initial stages of grapheme processing, as predicted by the disinhibited feedback theory. Using our high-resolution MEG source imaging technique (VESTAL), PTGA and V4 regions of interest (ROIs) were separately defined, and activity in response to the presentation of achromatic graphemes was measured. Activation levels in PTGA did not significantly differ between synesthetes and controls (suggesting similar grapheme processing mechanisms), whereas activation in V4 was significantly greater in synesthetes. In synesthetes, PTGA activation exceeded baseline levels beginning 105-109ms, and V4 activation did so 5ms later, suggesting nearly simultaneous activation of these areas. Results are discussed in the context of an updated version of the cross-activation model, the cascaded cross-tuning model of grapheme-color synesthesia.

  13. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, M.; Watson, E.B.; Acocella, J.

    1986-11-04

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10[sup 7] rad, the coloration resistant glass does not lose transparency. 3 figs.

  14. Radiation coloration resistant glass

    DOEpatents

    Tomozawa, Minoru; Watson, E. Bruce; Acocella, John

    1986-01-01

    A radiation coloration resistant glass is disclosed which is used in a radiation environment sufficient to cause coloration in most forms of glass. The coloration resistant glass includes higher proportions by weight of water and has been found to be extremely resistant to color change when exposed to such radiation levels. The coloration resistant glass is free of cerium oxide and has more than about 0.5% by weight water content. Even when exposed to gamma radiation of more than 10.sup.7 rad, the coloration resistant glass does not lose transparency.

  15. Objective color classification of ecstasy tablets by hyperspectral imaging.

    PubMed

    Edelman, Gerda; Lopatka, Martin; Aalders, Maurice

    2013-07-01

    The general procedure followed in the examination of ecstasy tablets for profiling purposes includes a color description, which depends highly on the observers' perception. This study aims to provide objective quantitative color information using visible hyperspectral imaging. Both self-manufactured and illicit tablets, created with different amounts of known colorants were analyzed. We derived reflectance spectra from hyperspectral images of these tablets, and successfully determined the most likely colorant used in the production of all self-manufactured tablets and four of five illicit tablets studied. Upon classification, the concentration of the colorant was estimated using a photon propagation model and a single reference measurement of a tablet of known concentration. The estimated concentrations showed a high correlation with the actual values (R(2) = 0.9374). The achieved color information, combined with other physical and chemical characteristics, can provide a powerful tool for the comparison of tablet seizures, which may reveal their origin.

  16. Perceptual Pragmatism and the Naturalized Ontology of Color.

    PubMed

    Chirimuuta, Mazviita

    2017-01-01

    This paper considers whether there can be any such thing as a naturalized metaphysics of color-any distillation of the commitments of perceptual science with regard to color ontology. I first make some observations about the kinds of philosophical commitments that sometimes bubble to the surface in the psychology and neuroscience of color. Unsurprisingly, because of the range of opinions expressed, an ontology of color cannot simply be read off from scientists' definitions and theoretical statements. I next consider two alternative routes. First, conceptual pluralism inspired by Mark Wilson's analysis of scientific representation. I argue that these findings leave the prospects for a naturalized color ontology rather dim. Second, I outline a naturalized epistemology of perception. I ask how the correctness and informativeness of perceptual states is understood by contemporary perceptual science. I argue that the detectionist ideal of correspondence should be replaced by the pragmatic ideal of usefulness. I argue that this result has significant implications for the metaphysics of color.

  17. Phylogenetic approach to the evolution of color term systems.

    PubMed

    Haynie, Hannah J; Bowern, Claire

    2016-11-29

    The naming of colors has long been a topic of interest in the study of human culture and cognition. Color term research has asked diverse questions about thought and communication, but no previous research has used an evolutionary framework. We show that there is broad support for the most influential theory of color term development (that most strongly represented by Berlin and Kay [Berlin B, Kay P (1969) (Univ of California Press, Berkeley, CA)]); however, we find extensive evidence for the loss (as well as gain) of color terms. We find alternative trajectories of color term evolution beyond those considered in the standard theories. These results not only refine our knowledge of how humans lexicalize the color space and how the systems change over time; they illustrate the promise of phylogenetic methods within the domain of cognitive science, and they show how language change interacts with human perception.

  18. A natural experiment on the condition-dependence of achromatic plumage reflectance in black-capped chickadees

    USGS Publications Warehouse

    D'Alba, L.; Van Hemert, C.; Handel, C.M.; Shawkey, M.D.

    2011-01-01

    Honest advertisement models posit that only individuals in good health can produce and/or maintain ornamental traits. Even though disease has profound effects on condition, few studies have experimentally tested its effects on trait expression and even fewer have identified a mechanistic basis for these effects. Recent evidence suggests that black and white, but not grey, plumage colors of black-capped chickadees (Poecile atricapillus) are sexually selected. We therefore hypothesized that birds afflicted with avian keratin disorder, a condition that affects the beak and other keratinized tissues, would show reduced expression of black and white, but not grey, color. UV-vis spectrometry of black-capped chickadees affected and unaffected by avian keratin disorder revealed spectral differences between them consistent with this hypothesis. To elucidate the mechanistic bases of these differences, we used scanning electron microscopy (SEM), electron-dispersive x-ray spectroscopy (EDX) and a feather cleaning experiment. SEM showed extreme feather soiling in affected birds, and EDX revealed that this was most likely from external sources. Experimentally cleaning the feathers increased color expression of ornamental feathers of affected, but not unaffected, birds. These data provide strong evidence that black and white color is an honest indicator in chickadees, and that variation in feather dirtiness, likely due to differences in preening behavior is a mechanism for this association.

  19. Color Adaptation for Color Deficient Learners.

    ERIC Educational Resources Information Center

    Johnson, Donald D.

    1995-01-01

    Describes a corrective method of color adaptation designed to allow most, if not all, individuals to participate in the learning process as well as social and work-related environments. Provides a concise summation of facts and theories concerning color deficiency. Includes anatomical drawings, graphs, and statistical data. (MJP)

  20. The Whorfian mind: Electrophysiological evidence that language shapes perception.

    PubMed

    Athanasopoulos, Panos; Wiggett, Alison; Dering, Benjamin; Kuipers, Jan-Rouke; Thierry, Guillaume

    2009-07-01

    Color perception has been a traditional test-case of the idea that the language we speak affects our perception of the world.1 It is now established that categorical perception of color is verbally mediated and varies with culture and language.2 However, it is unknown whether the well-demonstrated language effects on color discrimination really reach down to the level of visual perception, or whether they only reflect post-perceptual cognitive processes. Using brain potentials in a color oddball detection task with Greek and English speakers, we demonstrate that language effects may exist at a level that is literally perceptual, suggesting that speakers of different languages have differently structured minds.

  1. Color and Streptomycetes1

    PubMed Central

    Pridham, Thomas G.

    1965-01-01

    A report summarizing the results of an international workshop on determination of color of streptomycetes is presented. The results suggest that the color systems which seem most practically appealing and effective to specialists on actinomycetes are those embracing a limited number of color names and groups. The broad groupings allow placement of isolates into reasonably well-defined categories based on color of aerial mycelium. Attempts to expand such systems (more color groups) lead to difficulties. It is common knowledge that many, if not all, of the individual groups would in these broad systems contain strains that differ in many other respects, e.g., spore-wall ornamentation, color of vegetative (substratal) mycelium, morphology of chains of spores, and numerous physiological criteria. Also, cultures of intermediate color can be found, which makes placement difficult. As it now stands, color as a criterion for characterization of streptomycetes and streptoverticillia is in questionable status. Although much useful color information can be obtained by an individual, the application of this information to that in the literature or its use in communication with other individuals leaves much to be desired. More objective methods of color determination are needed. At present, the most effective method that could be used internationally is the color-wheel system of Tresner and Backus. Furthermore, the significance of color in speciation of these organisms is an open question. Obviously, more critical work on the color problem is needed. PMID:14264847

  2. How To Control Color Appearance With Instrumentation

    NASA Astrophysics Data System (ADS)

    Burns, Margaret E.

    1980-05-01

    Colorimetry, as defined by the International Commission on Illumination, is the measurement of colors, made possible by the properties of the eye and based on a set of conventions. Instrumentation for measuring object color, therefore, must be based on a human observer. The intent is to design an instrument that in effect responds as a person would, so that research development, production control and quality control areas have some means of assessing the acceptability of the appearance of a product. Investigations of a human observer's psychological response to color, and the manner in which visual observations are made, give the instrument designer and manufacturer data necessary to answer two questions: a. How can we put numbers (instrument read-out) on a perception that occurs in the brain of the observer? b. What can we learn from examination of a visual observing situation that will guide us in our design of an instrumental simulation of this situation? Involving as it does our own daily, almost unconscious, practice of making judgments concerning the things we see, the design and manufacture of color measurement instruments is an exceedingly interesting field. The advances being made concurrently today in research concerning human color vision and in optical and electronic technology will make possible increasingly useful instrumentation for quality control of product color.

  3. Solving the Brightness-from-Luminance Problem: A Neural Architecture for Invariant Brightness Perception

    DTIC Science & Technology

    1989-02-01

    lightness. Behavioral and Brain Sciences, 6, 625-692. Grossberg, S. (1987a). Cortical dynamics of three-dimensional form , color , and brightness...perception, I: Monocular theory. Perception and Psychophysics, 41, 87-116. Grossberg, S. (1987b). Cortical dynamics of three-dimensional form , color , and

  4. Perception of ensemble statistics requires attention.

    PubMed

    Jackson-Nielsen, Molly; Cohen, Michael A; Pitts, Michael A

    2017-02-01

    To overcome inherent limitations in perceptual bandwidth, many aspects of the visual world are represented as summary statistics (e.g., average size, orientation, or density of objects). Here, we investigated the relationship between summary (ensemble) statistics and visual attention. Recently, it was claimed that one ensemble statistic in particular, color diversity, can be perceived without focal attention. However, a broader debate exists over the attentional requirements of conscious perception, and it is possible that some form of attention is necessary for ensemble perception. To test this idea, we employed a modified inattentional blindness paradigm and found that multiple types of summary statistics (color and size) often go unnoticed without attention. In addition, we found attentional costs in dual-task situations, further implicating a role for attention in statistical perception. Overall, we conclude that while visual ensembles may be processed efficiently, some amount of attention is necessary for conscious perception of ensemble statistics.

  5. The Trouble with Color.

    ERIC Educational Resources Information Center

    Merchant, David

    1999-01-01

    Discusses problems with color quality in Web sites. Topics include differences in monitor settings, including contrast; amount of video RAM; user preference settings; browser-safe colors; cross-platform readability; and gamma values. (LRW)

  6. Focus on Color Photography

    ERIC Educational Resources Information Center

    Galindez, Peter

    1978-01-01

    Photographs and text describe techniques by which color negative film can be developed and printed. An equipment list, by which black and white printing facilities can be converted to make color prints, is provided. (CP)

  7. 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.

  8. Autophagy supports color vision

    PubMed Central

    Zhou, Zhenqing; Vinberg, Frans; Schottler, Frank; Doggett, Teresa A; Kefalov, Vladimir J; Ferguson, Thomas A

    2015-01-01

    Cones comprise only a small portion of the photoreceptors in mammalian retinas. However, cones are vital for color vision and visual perception, and their loss severely diminishes the quality of life for patients with retinal degenerative diseases. Cones function in bright light and have higher demand for energy than rods; yet, the mechanisms that support the energy requirements of cones are poorly understood. One such pathway that potentially could sustain cones under basal and stress conditions is macroautophagy. We addressed the role of macroautophagy in cones by examining how the genetic block of this pathway affects the structural integrity, survival, and function of these neurons. We found that macroautophagy was not detectable in cones under normal conditions but was readily observed following 24 h of fasting. Consistent with this, starvation induced phosphorylation of AMPK specifically in cones indicating cellular starvation. Inhibiting macroautophagy in cones by deleting the essential macroautophagy gene Atg5 led to reduced cone function following starvation suggesting that cones are sensitive to systemic changes in nutrients and activate macroautophagy to maintain their function. ATG5-deficiency rendered cones susceptible to light-induced damage and caused accumulation of damaged mitochondria in the inner segments, shortening of the outer segments, and degeneration of all cone types, revealing the importance of mitophagy in supporting cone metabolic needs. Our results demonstrate that macroautophagy supports the function and long-term survival of cones providing for their unique metabolic requirements and resistance to stress. Targeting macroautophagy has the potential to preserve cone-mediated vision during retinal degenerative diseases. PMID:26292183

  9. Autophagy supports color vision.

    PubMed

    Zhou, Zhenqing; Vinberg, Frans; Schottler, Frank; Doggett, Teresa A; Kefalov, Vladimir J; Ferguson, Thomas A

    2015-01-01

    Cones comprise only a small portion of the photoreceptors in mammalian retinas. However, cones are vital for color vision and visual perception, and their loss severely diminishes the quality of life for patients with retinal degenerative diseases. Cones function in bright light and have higher demand for energy than rods; yet, the mechanisms that support the energy requirements of cones are poorly understood. One such pathway that potentially could sustain cones under basal and stress conditions is macroautophagy. We addressed the role of macroautophagy in cones by examining how the genetic block of this pathway affects the structural integrity, survival, and function of these neurons. We found that macroautophagy was not detectable in cones under normal conditions but was readily observed following 24 h of fasting. Consistent with this, starvation induced phosphorylation of AMPK specifically in cones indicating cellular starvation. Inhibiting macroautophagy in cones by deleting the essential macroautophagy gene Atg5 led to reduced cone function following starvation suggesting that cones are sensitive to systemic changes in nutrients and activate macroautophagy to maintain their function. ATG5-deficiency rendered cones susceptible to light-induced damage and caused accumulation of damaged mitochondria in the inner segments, shortening of the outer segments, and degeneration of all cone types, revealing the importance of mitophagy in supporting cone metabolic needs. Our results demonstrate that macroautophagy supports the function and long-term survival of cones providing for their unique metabolic requirements and resistance to stress. Targeting macroautophagy has the potential to preserve cone-mediated vision during retinal degenerative diseases.

  10. Reimagining the Color Wheel

    ERIC Educational Resources Information Center

    Snyder, Jennifer

    2011-01-01

    Color wheels are a traditional project for many teachers. The author has used them in art appreciation classes for many years, but one problem she found when her pre-service art education students created colored wheels was that they were boring: simple circles, with pie-shaped pieces, which students either painted or colored in. This article…

  11. Color: Implications in dentistry

    PubMed Central

    Sikri, Vimal K

    2010-01-01

    The success of restorative dentistry is determined on the basis of functional and esthetic results. To achieve esthetics, four basic determinants are required in sequence; viz., position, contour, texture and color. The knowledge of the concept of color is essential for achieving good esthetics. This review compiles the various aspects of color, its measurements and shade matching in dentistry. PMID:21217954

  12. Biology of Skin Color.

    ERIC Educational Resources Information Center

    Corcos, Alain

    1983-01-01

    Information from scientific journals on the biology of skin color is discussed. Major areas addressed include: (1) biology of melanin, melanocytes, and melanosomes; (2) melanosome and human diversity; (3) genetics of skin color; and (4) skin color, geography, and natural selection. (JN)

  13. Color vision deficiencies

    NASA Astrophysics Data System (ADS)

    Vannorren, D.

    1982-04-01

    Congenital and acquired color vision defects are described in the context of physiological data. Light sources, photometry, color systems and test methods are described. A list of medicines is also presented. The practical social consequences of color vision deficiencies are discussed.

  14. Color Television in Instruction.

    ERIC Educational Resources Information Center

    Bretz, Rudy

    In spite of repeated research into the matter, no evidence has been discovered to support the claim that color television is superior to black-and-white television as an instructional aid. It is possible that there are advantages to color television which are unmeasured or unmeasurable, but the current claims for color; that it heightens realism,…

  15. Color Discrimination Work Sample.

    ERIC Educational Resources Information Center

    Shawsheen Valley Regional Vocational-Technical High School, Billerica, MA.

    This manual contains a work sample intended to assess a handicapped student's ability to see likenesses or differences in colors or shades, identifying or matching certain colors, and selecting colors that go together. Section 1 describes the assessment and lists related occupations and DOT codes. Instructions to the evaluator are provided in the…

  16. Simulation of concave-convex imaging mirror system for development of a compact and achromatic full-field x-ray microscope.

    PubMed

    Yamada, Jumpei; Matsuyama, Satoshi; Sano, Yasuhisa; Yamauchi, Kazuto

    2017-02-01

    We propose the use of two pairs of concave-convex mirrors as imaging optics for the compact full-field x-ray microscope with high resolution and magnification factors. The optics consists of two pairs of hyperbolic convex and elliptical concave mirrors with the principal surface near the object, consequently enabling the focal length to be 10 times shorter than conventional advanced Kirkpatrick-Baez mirror optics. This paper describes characteristics of the optics calculated by ray-tracing and wave-optical simulators. The expected spatial resolution is approximately 40 nm with a wide field of view of more than 10 μm and a total length of about 2 m, which may lead to the possibility of laboratory-sized, achromatic, and high-resolution full-field x-ray microscopes.

  17. The Munsell Color System: a scientific compromise from the world of art.

    PubMed

    Cochrane, Sally

    2014-09-01

    Color systems make accurate color specification and matching possible in science, art, and industry by defining a coordinate system for all possible color perceptions. The Munsell Color System, developed by the artist Albert Henry Munsell in the early twentieth century, has influenced color science to this day. I trace the development of the Munsell Color System from its origins in the art world to its acceptance in the scientific community. Munsell's system was the first to accurately and quantitatively describe the psychological experience of color. By considering the problems that color posed for Munsell's art community and examining his diaries and published material, I conclude that Munsell arrived at his results by remaining agnostic as to the scientific definition of color, while retaining faith that color perceptions could be objectively quantified. I argue that Munsell was able to interest the scientific community in his work because color had become a controversial topic between physicists and psychologists. Parts of Munsell's system appealed to each field, making it a workable compromise. For contrast, I suggest that three contemporary scientists with whom Munsell had contact--Wilhelm Ostwald, Ogden Rood, and Edward Titchener--did not reach the same conclusions in their color systems because they started from scientific assumptions about the nature of color.

  18. Changing Perceptions

    ERIC Educational Resources Information Center

    Mallett, Susanne; Wren, Steve; Dawes, Mark; Blinco, Amy; Haines, Brett; Everton, Jenny; Morgan, Ellen; Barton, Craig; Breen, Debbie; Ellison, Geraldine; Burgess, Danny; Stavrou, Jim; Carre, Catherine; Watson, Fran; Cherry, David; Hawkins, Chris; Stapenhill-Hunt, Maria; Gilderdale, Charlie; Kiddle, Alison; Piggott, Jennifer

    2009-01-01

    A group of teachers involved in embedding NRICH tasks (http://nrich.maths.org) into their everyday practice were keen to challenge common perceptions of mathematics, and of the teaching and learning of mathematics. In this article, the teachers share what they are doing to change these perceptions in their schools.

  19. Machine perception

    SciTech Connect

    Not Available

    1982-01-01

    The book is aimed at the level of a graduate student or the practising professional and discusses visual perception by computers. Topics covered include: pattern classification methods; polyhedra scenes; shape analysis and recognition; perception of brightness and colour; edge and curve detection; region segmentation; texture analysis; depth measurement analysis; knowledge-based systems and applications. A subject index is included.

  20. The Organization of Shape and Color in Vision and Art

    PubMed Central

    Pinna, Baingio

    2011-01-01

    The aim of this work is to study the phenomenal organization of shape and color in vision and art in terms of microgenesis of the object perception and creation. The idea of “microgenesis” is that the object perception and creation takes time to develop. Our hypothesis is that the roles of shape and color are extracted in sequential order and in the same order these roles are also used by artists to paint objects. Boundary contours are coded before color contours. The microgenesis of the object formation was demonstrated (i) by introducing new conditions derived from the watercolor illusion, where the juxtaposed contours are displaced horizontally or vertically, and based on variations of Matisse’s Woman, (ii) by studying descriptions and replications of visual objects in adults and children of different ages, and (iii) by analyzing the linguistic sequence and organization in a free naming task of the attributes related to shape and color. The results supported the idea of the microgenesis of the object perception, namely the temporal order in the formation of the roles of the object properties (shape before color). Some general principles were extracted from the experimental results. They can be a starting point to explore a new domain focused on the microgenesis of shape and color within the more general problem of object organization, where integrated and multidisciplinary studies based on art and vision science can be very useful. PMID:22065954

  1. Development of a novel 2D color map for interactive segmentation of histological images

    PubMed Central

    Chaudry, Qaiser; Sharma, Yachna; Raza, Syed H.; Wang, May D.

    2016-01-01

    We present a color segmentation approach based on a two-dimensional color map derived from the input image. Pathologists stain tissue biopsies with various colored dyes to see the expression of biomarkers. In these images, because of color variation due to inconsistencies in experimental procedures and lighting conditions, the segmentation used to analyze biological features is usually ad-hoc. Many algorithms like K-means use a single metric to segment the image into different color classes and rarely provide users with powerful color control. Our 2D color map interactive segmentation technique based on human color perception information and the color distribution of the input image, enables user control without noticeable delay. Our methodology works for different staining types and different types of cancer tissue images. Our proposed method’s results show good accuracy with low response and computational time making it a feasible method for user interactive applications involving segmentation of histological images.

  2. Color Classification of Coordination Compounds.

    ERIC Educational Resources Information Center

    Poncini, Laurence; Wimmer, Franz L.

    1987-01-01

    Proposes that colored compounds be classified by reference to a standard color-order system incorporating a color dictionary. Argues that the colors of new compounds could be incorporated into the characterization process and into computer storage systems. (TW)

  3. Watermarking spot colors

    NASA Astrophysics Data System (ADS)

    Alattar, Osama M.; Reed, Alastair M.

    2003-06-01

    Watermarking of printed materials has usually focused on process inks of cyan, magenta, yellow and black (CMYK). In packaging, almost three out of four printed materials include spot colors. Spot colors are special premixed inks, which can be produced in a vibrant range of colors, often outside the CMYK color gamut. In embedding a watermark into printed material, a common approach is to modify the luminance value of each pixel in the image. In the case of process color work pieces, the luminance change can be scaled to the C, M, Y and K channels using a weighting function, to produce the desired change in luminance. In the case of spot color art designs, there is only one channel available and the luminance change is applied to this channel. In this paper we develop a weighting function to embed the watermark signal across the range of different spot colors. This weighting function normalizes visibility effect and signal robustness across a wide range of different spot colors. It normalizes the signal robustness level over the range of an individual spot color"s intensity levels. Further, it takes into account the sensitivity of the capturing device to the different spot colors.

  4. True Colors Shining Through

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This image mosaic illustrates how scientists use the color calibration targets (upper left) located on both Mars Exploration Rovers to fine-tune the rovers' sense of color. In the center, spectra, or light signatures, acquired in the laboratory of the colored chips on the targets are shown as lines. Actual data from Mars Exploration Rover Spirit's panoramic camera is mapped on top of these lines as dots. The plot demonstrates that the observed colors of Mars match the colors of the chips, and thus approximate the red planet's true colors. This finding is further corroborated by the picture taken on Mars of the calibration target, which shows the colored chips as they would appear on Earth.

  5. Acquired color vision deficiency.

    PubMed

    Simunovic, Matthew P

    2016-01-01

    Acquired color vision deficiency occurs as the result of ocular, neurologic, or systemic disease. A wide array of conditions may affect color vision, ranging from diseases of the ocular media through to pathology of the visual cortex. Traditionally, acquired color vision deficiency is considered a separate entity from congenital color vision deficiency, although emerging clinical and molecular genetic data would suggest a degree of overlap. We review the pathophysiology of acquired color vision deficiency, the data on its prevalence, theories for the preponderance of acquired S-mechanism (or tritan) deficiency, and discuss tests of color vision. We also briefly review the types of color vision deficiencies encountered in ocular disease, with an emphasis placed on larger or more detailed clinical investigations.

  6. Database of synesthetic color associations for Japanese kanji.

    PubMed

    Hamada, Daisuke; Yamamoto, Hiroki; Saiki, Jun

    2017-02-01

    Synesthesia is a neurological phenomenon in which certain types of stimuli elicit involuntary perceptions in an unrelated pathway. A common type of synesthesia is grapheme-color synesthesia, in which the visual perception of letters and numbers stimulates the perception of a specific color. Previous studies have often collected relatively small numbers of grapheme-color associations per synesthete, but the accumulation of a large quantity of data has greater promise for uncovering the mechanisms underlying synesthetic association. In this study, we therefore collected large samples of data from a total of eight synesthetes. All told, we obtained over 1000 synesthetic colors associated with Japanese kanji characters from each of two synesthetes, over 100 synesthetic colors form each of three synesthetes, and about 80 synesthetic colors associated with Japanese hiragana, Latin letters, and Arabic numerals from each of three synesthetes. We then compiled the data into a database, called the KANJI-Synesthetic Colors Database (K-SCD), which has a total of 5122 colors for 483, 46, and 46 Japanese kanji, hiragana, and katakana characters, respectively, as well as for 26 Latin letters and ten Arabic numerals. In addition to introducing the K-SCD, this article demonstrates the database's merits by using two examples, in which two new rules for synesthetic association, "shape similarity" and "synesthetic color clustering," were found. The K-SCD is publicly accessible ( www.cv.jinkan.kyoto-u.ac.jp/site/uploads/K-SCD.xlsm ) and will be a valuable resource for those who wish to conduct statistical analyses using a rich dataset in order to uncover the rules governing synesthetic association and to understand its mechanisms.

  7. A review of color blindness for microscopists: guidelines and tools for accommodating and coping with color vision deficiency.

    PubMed

    Keene, Douglas R

    2015-04-01

    "Color blindness" is a variable trait, including individuals with just slight color vision deficiency to those rare individuals with a complete lack of color perception. Approximately 75% of those with color impairment are green diminished; most of those remaining are red diminished. Red-Green color impairment is sex linked with the vast majority being male. The deficiency results in reds and greens being perceived as shades of yellow; therefore red-green images presented to the public will not illustrate regions of distinction to these individuals. Tools are available to authors wishing to accommodate those with color vision deficiency; most notable are components in FIJI (an extension of ImageJ) and Adobe Photoshop. Using these tools, hues of magenta may be substituted for red in red-green images resulting in striking definition for both the color sighted and color impaired. Web-based tools may be used (importantly) by color challenged individuals to convert red-green images archived in web-accessible journal articles into two-color images, which they may then discern.

  8. Colors, colored overlays, and reading skills.

    PubMed

    Uccula, Arcangelo; Enna, Mauro; Mulatti, Claudio

    2014-01-01

    In this article, we are concerned with the role of colors in reading written texts. It has been argued that colored overlays applied above written texts positively influence both reading fluency and reading speed. These effects would be particularly evident for those individuals affected by the so called Meares-Irlen syndrome, i.e., who experience eyestrain and/or visual distortions - e.g., color, shape, or movement illusions - while reading. This condition would interest the 12-14% of the general population and up to the 46% of the dyslexic population. Thus, colored overlays have been largely employed as a remedy for some aspects of the difficulties in reading experienced by dyslexic individuals, as fluency and speed. Despite the wide use of colored overlays, how they exert their effects has not been made clear yet. Also, according to some researchers, the results supporting the efficacy of colored overlays as a tool for helping readers are at least controversial. Furthermore, the very nature of the Meares-Irlen syndrome has been questioned. Here we provide a concise, critical review of the literature.

  9. Colors, colored overlays, and reading skills

    PubMed Central

    Uccula, Arcangelo; Enna, Mauro; Mulatti, Claudio

    2014-01-01

    In this article, we are concerned with the role of colors in reading written texts. It has been argued that colored overlays applied above written texts positively influence both reading fluency and reading speed. These effects would be particularly evident for those individuals affected by the so called Meares-Irlen syndrome, i.e., who experience eyestrain and/or visual distortions – e.g., color, shape, or movement illusions – while reading. This condition would interest the 12–14% of the general population and up to the 46% of the dyslexic population. Thus, colored overlays have been largely employed as a remedy for some aspects of the difficulties in reading experienced by dyslexic individuals, as fluency and speed. Despite the wide use of colored overlays, how they exert their effects has not been made clear yet. Also, according to some researchers, the results supporting the efficacy of colored overlays as a tool for helping readers are at least controversial. Furthermore, the very nature of the Meares-Irlen syndrome has been questioned. Here we provide a concise, critical review of the literature. PMID:25120525

  10. Miniature Color Display Phase 4

    DTIC Science & Technology

    1993-05-01

    is used to generate full color. By spectral tuning of the xenon arc-lamp backlight and the color polarizers, a color gamut comparable to that of a...5 1.2 Phase IV Accom plishments ................................... 5 1.2.1 Subtractive Color Gamut ...Technical Achievem ents .............................................. 8 2.1 Subtractive Color Gamut 2.1.1 Sub Color LC Technology

  11. Color Reproduction with a Smartphone

    ERIC Educational Resources Information Center

    Thoms, Lars-Jochen; Colicchia, Giuseppe; Girwidz, Raimund

    2013-01-01

    The world is full of colors. Most of the colors we see around us can be created on common digital displays simply by superposing light with three different wavelengths. However, no mixture of colors can produce a fully pure color identical to a spectral color. Using a smartphone, students can investigate the main features of primary color addition…

  12. Modeling of display color parameters and algorithmic color selection

    NASA Astrophysics Data System (ADS)

    Silverstein, Louis D.; Lepkowski, James S.; Carter, Robert C.; Carter, Ellen C.

    1986-01-01

    An algorithmic approach to color selection, which is based on psychophysical models of color processing, is described. The factors that affect color differentiation, such as wavelength separation, color stimulus size, and brightness adaptation level, are discussed. The use of the CIE system of colorimetry and the CIELUV color difference metric for display color modeling is examined. The computer program combines the selection algorithm with internally derived correction factors for color image field size, ambient lighting characteristics, and anomalous red-green color vision deficiencies of display operators. The performance of the program is evaluated and uniform chromaticity scale diagrams for six-color and seven-color selection problems are provided.

  13. Associative memory advantage in grapheme-color synesthetes compared to older, but not young adults

    PubMed Central

    Pfeifer, Gaby; Rothen, Nicolas; Ward, Jamie; Chan, Dennis; Sigala, Natasha

    2014-01-01

    People with grapheme-color synesthesia perceive enriched experiences of colors in response to graphemes (letters, digits). In this study, we examined whether these synesthetes show a generic associative memory advantage for stimuli that do not elicit a synesthetic color. We used a novel between group design (14 young synesthetes, 14 young, and 14 older adults) with a self-paced visual associative learning paradigm and subsequent retrieval (immediate and delayed). Non-synesthesia inducing, achromatic fractal pair-associates were manipulated in visual similarity (high and low) and corresponded to high and low memory load conditions. The main finding was a learning and retrieval advantage of synesthetes relative to older, but not to younger, adults. Furthermore, the significance testing was supported with effect size measures and power calculations. Differences between synesthetes and older adults were found during dissimilar pair (high memory load) learning and retrieval at immediate and delayed stages. Moreover, we found a medium size difference between synesthetes and young adults for similar pair (low memory load) learning. Differences between young and older adults were also observed during associative learning and retrieval, but were of medium effect size coupled with low power. The results show a subtle associative memory advantage in synesthetes for non-synesthesia inducing stimuli, which can be detected against older adults. They also indicate that perceptual mechanisms (enhanced in synesthesia, declining as part of the aging process) can translate into a generic associative memory advantage, and may contribute to associative deficits accompanying healthy aging. PMID:25071664

  14. Information through color imagery

    USGS Publications Warehouse

    Colvocoresses, Alden P.

    1975-01-01

    The color-sensing capability of the human eye is a powerful tool. In remote sensing we should use color to display data more meaningfully, not to re-create the scene. Color disappears with distance, and features change color with viewing angle. Color infrared film lets us apply color with additional meaning even though we introduce a false color response. Although the marginal gray scale on an ERTS (Earth Resources Technology Satellite) image may indicate balance between the green, red, and infrared bands, and although each band may be printed in a primary color, tests show that we are not fully applying the three primary colors. Therefore, contrast in the green band should be raised. For true three-color remote sensing of the Earth, we must find two generally meaningful signatures in the visible spectrum, or perhaps extend our spectral range. Before turning to costly digital processing we should explore analog processing. Most ERTS users deal with relative spectral radiance; the few concerned with absolute radiance could use the computer-compatible tapes or special annotations. NASA (National Aeronautics and Space Administration), which assigns the range and contrast to the ERTS image, controls processing and could adjust the density range for maximum contrast in any ERTS scene. NASA cannot alter processing for local changes in reflective characteristics of the Earth but could adjust for Sun elevation and optimize the contrast in a given band.

  15. Selection of small color palette for color image quantization

    NASA Astrophysics Data System (ADS)

    Chau, Wing K.; Wong, S. K. M.; Yang, Xuedong; Wan, Shijie J.

    1992-05-01

    Two issues are involved in color image quantization: color palette selection and color mapping. A common practice for color palette selection is to minimize the color distortion for each pixel (the median-cut, the variance-based and the k-means algorithms). After the color palette has been chosen, a quantized image may be generated by mapping the original color of each pixel onto its nearest color in the color palette. Such an approach can usually produce quantized images of high quality with 128 or more colors. For 32 - 64 colors, the quality of the quantized images is often acceptable with the aid of dithering techniques in the color mapping process. For 8 - 16 color, however, the above statistical method for color selection becomes no longer suitable because of the great reduction of color gamut. In order to preserve the color gamut of the original image, one may want to select the colors in such a way that the convex hull formed by these colors in the RGB color space encloses most colors of the original image. Quantized images generated in such a geometrical way usually preserve a lot of image details, but may contain too much high frequency noises. This paper presents an effective algorithm for the selection of very small color palette by combining the strengths of the above statistical and geometrical approaches. We demonstrate that with the new method images of high quality can be produced by using only 4 to 8 colors.

  16. A Simple Principled Approach for Modeling and Understanding Uniform Color Metrics

    PubMed Central

    Smet, Kevin A.G.; Webster, Michael A.; Whitehead, Lorne A.

    2016-01-01

    An important goal in characterizing human color vision is to order color percepts in a way that captures their similarities and differences. This has resulted in the continuing evolution of “uniform color spaces,” in which the distances within the space represent the perceptual differences between the stimuli. While these metrics are now very successful in predicting how color percepts are scaled, they do so in largely empirical, ad hoc ways, with limited reference to actual mechanisms of color vision. In this article our aim is to instead begin with general and plausible assumptions about color coding, and then develop a model of color appearance that explicitly incorporates them. We show that many of the features of empirically-defined color order systems (such as those of Munsell, Pantone, NCS, and others) as well as many of the basic phenomena of color perception, emerge naturally from fairly simple principles of color information encoding in the visual system and how it can be optimized for the spectral characteristics of the environment. PMID:26974939

  17. The diversity of male nuptial coloration leads to species diversity in Lake Victoria cichlids.

    PubMed

    Miyagi, Ryutaro; Terai, Yohey

    2013-01-01

    The amazing coloration shown by diverse cichlid fish not only fascinates aquarium keepers, but also receives great attention from biologists interested in speciation because of its recently-revealed role in their adaptive radiation in an African lake. We review the important role of coloration in the speciation and adaptive evolution of Lake Victoria cichlids, which have experienced adaptive radiation during a very short evolutionary period. Mature male cichlids display their colors during mate choice. The color of their skin reflects light, and the reflected light forms a color signal that is received by the visual system of females. The adaptive divergence of visual perceptions shapes and diverges colorations, to match the adapted visual perceptions. The divergence of visual perception and coloration indicates that the divergence of color signals causes reproductive isolation between species, and this process leads to speciation. Differences in color signals among coexisting species act to maintain reproductive isolation by preventing hybridization. Thus, the diversity of coloration has caused speciation and has maintained species diversity in Lake Victoria cichlids.

  18. Watermarking spot colors in packaging

    NASA Astrophysics Data System (ADS)

    Reed, Alastair; Filler, TomáÅ.¡; Falkenstern, Kristyn; Bai, Yang

    2015-03-01

    In January 2014, Digimarc announced Digimarc® Barcode for the packaging industry to improve the check-out efficiency and customer experience for retailers. Digimarc Barcode is a machine readable code that carries the same information as a traditional Universal Product Code (UPC) and is introduced by adding a robust digital watermark to the package design. It is imperceptible to the human eye but can be read by a modern barcode scanner at the Point of Sale (POS) station. Compared to a traditional linear barcode, Digimarc Barcode covers the whole package with minimal impact on the graphic design. This significantly improves the Items per Minute (IPM) metric, which retailers use to track the checkout efficiency since it closely relates to their profitability. Increasing IPM by a few percent could lead to potential savings of millions of dollars for retailers, giving them a strong incentive to add the Digimarc Barcode to their packages. Testing performed by Digimarc showed increases in IPM of at least 33% using the Digimarc Barcode, compared to using a traditional barcode. A method of watermarking print ready image data used in the commercial packaging industry is described. A significant proportion of packages are printed using spot colors, therefore spot colors needs to be supported by an embedder for Digimarc Barcode. Digimarc Barcode supports the PANTONE spot color system, which is commonly used in the packaging industry. The Digimarc Barcode embedder allows a user to insert the UPC code in an image while minimizing perceptibility to the Human Visual System (HVS). The Digimarc Barcode is inserted in the printing ink domain, using an Adobe Photoshop plug-in as the last step before printing. Since Photoshop is an industry standard widely used by pre-press shops in the packaging industry, a Digimarc Barcode can be easily inserted and proofed.

  19. Characteristics of grouping colors for figure segregation on a multicolored background.

    PubMed

    Nagai, Takehiro; Uchikawa, Keiji

    2008-11-01

    A figure is segregated from its background when the colored elements belonging to the figure are grouped together. We investigated the range of color distribution conditions in which a figure could be segregated from its background using the color distribution differences. The stimulus was a multicolored texture composed of randomly shaped pieces. It was divided into two regions: a test region and a background region. The pieces in these two regions had different color distributions in the OSA Uniform Color Space. In our experiments, the subject segregated the figure of the test region using two different procedures. Since the Euclidean distance in the OSA Uniform Color Space corresponds to perceived color difference, if segregation thresholds are determined by only color difference, the thresholds should be independent of position and direction in the color space. In the results, however, the thresholds did depend on position and direction in the OSA Uniform Color Space. This suggests that color difference is not the only factor in figure segregation by color. Moreover, the threshold dependence on position and direction is influenced by the distances in the cone-opponent space whose axes are normalized by discrimination thresholds, suggesting that figure segregation threshold is determined by similar factors in the cone-opponent space for color discrimination. The analysis of the results by categorical color naming suggests that categorical color perception may affect figure segregation only slightly.

  20. Color categories: evidence for the cultural relativity hypothesis.

    PubMed

    Roberson, Debi; Davidoff, Jules; Davies, Ian R L; Shapiro, Laura R

    2005-06-01

    The question of whether language affects our categorization of perceptual continua is of particular interest for the domain of color where constraints on categorization have been proposed both within the visual system and in the visual environment. Recent research (Roberson, Davies, & Davidoff, 2000; Roberson et al., in press) found substantial evidence of cognitive color differences between different language communities, but concerns remained as to how representative might be a tiny, extremely remote community. The present study replicates and extends previous findings using additional paradigms among a larger community in a different visual environment. Adult semi-nomadic tribesmen in Southern Africa carried out similarity judgments, short-term memory and long-term learning tasks. They showed different cognitive organization of color to both English and another language with the five color terms. Moreover, Categorical Perception effects were found to differ even between languages with broadly similar color categories. The results provide further evidence of the tight relationship between language and cognition.

  1. Colorimetry-based edge preservation approach for color image enhancement

    NASA Astrophysics Data System (ADS)

    Suresh, Merugu; Jain, Kamal

    2016-07-01

    "Subpixel-based downsampling" is an approach that can implicitly enhance perceptible image resolution of a downsampled image by managing subpixel-level representation preferably with individual pixel. A subpixel-level representation for color image sample at edge region and color image representation is focused with the problem of directional filtration based on horizontal and vertical orientations using colorimetric color space with the help of saturation and desaturation pixels. A diagonal tracing algorithm and an edge preserving approach with colorimetric color space were used for color image enhancement. Since, there exist high variations at the edge regions, it could not be considered as constant or zero, and when these variations are random the need to compensate these to minimum value and then process for image representation. Finally, the results of the proposed method show much better image information as compared with traditional direct pixel-based methods with increased luminance and chrominance resolutions.

  2. Quaternion-Michelson Descriptor for Color Image Classification.

    PubMed

    Lan, Rushi; Zhou, Yicong

    2016-09-02

    In this paper, we develop a simple yet powerful framework called Quaternion-Michelson Descriptor (QMD) to extract local features for color image classification. Unlike traditional local descriptors extracted directly from the original (raw) image space, QMD is derived from the Michelson contrast law and the quaternionic representation (QR) of color images. The Michelson contrast is a stable measurement of image contents from the viewpoint of human perception, while QR is able to handle all the color information of the image holisticly and to preserve the interactions among different color channels. In this way, QMD integrates both merits of Michelson contrast and QR. Based on the QMD framework, we further propose two novel Quaternionic Michelson Contrast Binary Pattern (QMCBP) descriptors from different perspectives. Experiments and comparisons on different color image classification databases demonstrate that the proposed framework and descriptors outperform several state-of-the-art methods.

  3. Quaternion-Michelson Descriptor for Color Image Classification.

    PubMed

    Lan, Rushi; Zhou, Yicong

    2016-11-01

    In this paper, we develop a simple yet powerful framework called quaternion-Michelson descriptor (QMD) to extract local features for color image classification. Unlike traditional local descriptors extracted directly from the original (raw) image space, QMD is derived from the Michelson contrast law and the quaternionic representation (QR) of color images. The Michelson contrast is a stable measurement of image contents from the viewpoint of human perception, while QR is able to handle all the color information of the image holisticly and to preserve the interactions among different color channels. In this way, QMD integrates both the merits of Michelson contrast and QR. Based on the QMD framework, we further propose two novel quaternionic Michelson contrast binary pattern descriptors from different perspectives. Experiments and comparisons on different color image classification databases demonstrate that the proposed framework and descriptors outperform several state-of-the-art methods.

  4. Digital color representation

    DOEpatents

    White, James M.; Faber, Vance; Saltzman, Jeffrey S.

    1992-01-01

    An image population having a large number of attributes is processed to form a display population with a predetermined smaller number of attributes which represent the larger number of attributes. In a particular application, the color values in an image are compressed for storage in a discrete lookup table (LUT) where an 8-bit data signal is enabled to form a display of 24-bit color values. The LUT is formed in a sampling and averaging process from the image color values with no requirement to define discrete Voronoi regions for color compression. Image color values are assigned 8-bit pointers to their closest LUT value whereby data processing requires only the 8-bit pointer value to provide 24-bit color values from the LUT.

  5. [Diagnosis and classification of variants of color vision in the light of new methodological approaches].

    PubMed

    Volkov, V V; Iustova, E N

    1995-01-01

    The authors suggest that the parameters of color force of the receptors and the possible abnormal disposition of their maximal sensitivity by the spectrum be taken into consideration in the diagnosis of color perception. Assessment of color force was acknowledged to be more significant than of color abnormalities, both from a viewpoint of occupational selection, and from a clinical viewpoint. This is reflected in the suggested classification of color vision and in recommendations for use in practical ophthalmology of new threshold tables created by Yustova-Alexeyeva et al. These tables are based on the results of colorimetric investigations, and the results of their trials are reliable.

  6. Water Detection Based on Color Variation

    NASA Technical Reports Server (NTRS)

    Rankin, Arturo L.

    2012-01-01

    This software has been designed to detect water bodies that are out in the open on cross-country terrain at close range (out to 30 meters), using imagery acquired from a stereo pair of color cameras mounted on a terrestrial, unmanned ground vehicle (UGV). This detector exploits the fact that the color variation across water bodies is generally larger and more uniform than that of other naturally occurring types of terrain, such as soil and vegetation. Non-traversable water bodies, such as large puddles, ponds, and lakes, are detected based on color variation, image intensity variance, image intensity gradient, size, and shape. At ranges beyond 20 meters, water bodies out in the open can be indirectly detected by detecting reflections of the sky below the horizon in color imagery. But at closer range, the color coming out of a water body dominates sky reflections, and the water cue from sky reflections is of marginal use. Since there may be times during UGV autonomous navigation when a water body does not come into a perception system s field of view until it is at close range, the ability to detect water bodies at close range is critical. Factors that influence the perceived color of a water body at close range are the amount and type of sediment in the water, the water s depth, and the angle of incidence to the water body. Developing a single model of the mixture ratio of light reflected off the water surface (to the camera) to light coming out of the water body (to the camera) for all water bodies would be fairly difficult. Instead, this software detects close water bodies based on local terrain features and the natural, uniform change in color that occurs across the surface from the leading edge to the trailing edge.

  7. Accurate spectral color measurements

    NASA Astrophysics Data System (ADS)

    Hiltunen, Jouni; Jaeaeskelaeinen, Timo; Parkkinen, Jussi P. S.

    1999-08-01

    Surface color measurement is of importance in a very wide range of industrial applications including paint, paper, printing, photography, textiles, plastics and so on. For a demanding color measurements spectral approach is often needed. One can measure a color spectrum with a spectrophotometer using calibrated standard samples as a reference. Because it is impossible to define absolute color values of a sample, we always work with approximations. The human eye can perceive color difference as small as 0.5 CIELAB units and thus distinguish millions of colors. This 0.5 unit difference should be a goal for the precise color measurements. This limit is not a problem if we only want to measure the color difference of two samples, but if we want to know in a same time exact color coordinate values accuracy problems arise. The values of two instruments can be astonishingly different. The accuracy of the instrument used in color measurement may depend on various errors such as photometric non-linearity, wavelength error, integrating sphere dark level error, integrating sphere error in both specular included and specular excluded modes. Thus the correction formulas should be used to get more accurate results. Another question is how many channels i.e. wavelengths we are using to measure a spectrum. It is obvious that the sampling interval should be short to get more precise results. Furthermore, the result we get is always compromise of measuring time, conditions and cost. Sometimes we have to use portable syste or the shape and the size of samples makes it impossible to use sensitive equipment. In this study a small set of calibrated color tiles measured with the Perkin Elmer Lamda 18 and the Minolta CM-2002 spectrophotometers are compared. In the paper we explain the typical error sources of spectral color measurements, and show which are the accuracy demands a good colorimeter should have.

  8. Pitch perception.

    PubMed

    Yost, William A

    2009-11-01

    This article is a review of the psychophysical study of pitch perception. The history of the study of pitch has seen a continual competition between spectral and temporal theories of pitch perception. The pitch of complex stimuli is likely based on the temporal regularities in a sound's waveform, with the strongest pitches occurring for stimuli with low-frequency components. Thus, temporal models, especially those based on autocorrelation-like processes, appear to account for the majority of the data.

  9. MonoColor CMOS sensor

    NASA Astrophysics Data System (ADS)

    Wang, Ynjiun P.

    2009-02-01

    A new breed of CMOS color sensor called MonoColor sensor is developed for a barcode reading application in AIDC industry. The RGBW color filter array (CFA) in a MonoColor sensor is arranged in a 8 x 8 pixels CFA with only 4 pixels of them are color (RGB) pixels and the rest of 60 pixels are transparent or monochrome. Since the majority of pixels are monochrome, MonoColor sensor maintains 98% barcode decode performance compared with a pure monochrome CMOS sensor. With the help of monochrome and color pixel fusion technique, the resulting color pictures have similar color quality in terms of Color Semantic Error (CSE) compared with a Bayer pattern (RGB) CMOS color camera. Since monochrome pixels are more sensitive than color pixels, a MonoColor sensor produces in general about 2X brighter color picture and higher luminance pixel resolution.

  10. Fruit color preference by birds and applications to ecological restoration.

    PubMed

    Gagetti, B L; Piratelli, A J; Piña-Rodrigues, F C M

    2016-01-01

    Ecological restoration aims to retrieve not only the structure but also the functionality of ecosystems. Frugivorous birds may play an important role in this process due to their efficiency in seed dispersal. Color perception in these animals is highly developed, and then the colors of fleshy fruits may provide important clues for choosing plant species for restoration plans. This study aims to integrate bird color preferences and restoration of degraded areas, with an objective to evaluate the potential attractiveness to birds by colored fruits. We carried out an experiment with 384 artificial fruits made of edible modeling clay with the following colors: black, blue, green and red, with 96 fruits of each color in six sites, including four restored areas and two second-growth forest fragments. We also tested the possible effect of light intensity on fruit consumption by color. A total of 120 (38.6%) were assumed to be consumed by birds, and the fruit consumption varied in response to the location and light incidence. Consumption of black and blue fruits was not related to site by chance. Notwithstanding, red and black fruits were consumed significantly more than any other colors, emphasizing bird preference to these colors, regardless of location. Enrichment with shade tolerant shrubs or forest species with black or red fruits may be an alternative way to manage established restorations. In recently established or new restorations, one may introduce pioneer shrubs or short-lived forest species which have blue fruits, but also those having black or red ones.

  11. Spatial Brightness Perception of Trichromatic Stimuli

    SciTech Connect

    Royer, Michael P.; Houser, Kevin W.

    2012-11-16

    An experiment was conducted to examine the effect of tuning optical radiation on brightness perception for younger (18-25 years of age) and older (50 years of age or older) observers. Participants made forced-choice evaluations of the brightness of a full factorial of stimulus pairs selected from two groups of four metameric stimuli. The large-field stimuli were created by systematically varying either the red or the blue primary of an RGB LED mixture. The results indicate that light stimuli of equal illuminance and chromaticity do not appear equally bright to either younger or older subjects. The rank-order of brightness is not predicted by any current model of human vision or theory of brightness perception including Scotopic to Photopic or Cirtopic to Photopic ratio theory, prime color theory, correlated color temperature, V(λ)-based photometry, color quality metrics, linear brightness models, or color appearance models. Age may affect brightness perception when short-wavelength primaries are used, especially those with a peak wavelength shorter than 450 nm. The results suggest further development of metrics to predict brightness perception is warranted, and that including age as a variable in predictive models may be valuable.

  12. Color consilience: color through the lens of art practice, history, philosophy, and neuroscience.

    PubMed

    Conway, Bevil R

    2012-03-01

    Paintings can be interpreted as the product of the complex neural machinery that translates physical light signals into behavior, experience, and emotion. The brain mechanisms responsible for vision and perception have been sculpted during evolution and further modified by cultural exposure and development. By closely examining artists' paintings and practices, we can discover hints to how the brain works, and achieve insight into the discoveries and inventions of artists and their impact on culture. Here, I focus on an integral aspect of color, color contrast, which poses a challenge for artists: a mark situated on an otherwise blank canvas will appear a different color in the context of the finished painting. How do artists account for this change in color during the production of a painting? In the broader context of neural and philosophical considerations of color, I discuss the practices of three modern masters, Henri Matisse, Paul Cézanne, and Claude Monet, and suggest that the strategies they developed not only capitalized on the neural mechanisms of color, but also influenced the trajectory of western art history.

  13. Faculty and Administrators of Color in the Pennsylvania State System of Higher Education: A Status Report.

    ERIC Educational Resources Information Center

    Taliaferro, Barbara M.; Montoya, Alicia L.

    Data from the Pennsylvania State System of Higher Education (SSHE) indicate that men of color represent 13.1 percent of administrative positions and 6.42 percent of faculty positions, while women of color hold 9.66 percent of administrative positions and 4.05 percent of faculty positions. A study was conducted to compare the perceptions of 32 SSHE…

  14. Support for Lateralization of the Whorf Effect beyond the Realm of Color Discrimination

    ERIC Educational Resources Information Center

    Gilbert, Aubrey L.; Regier, Terry; Kay, Paul; Ivry, Richard B.

    2008-01-01

    Recent work has shown that Whorf effects of language on color discrimination are stronger in the right visual field than in the left. Here we show that this phenomenon is not limited to color: The perception of animal figures (cats and dogs) was more strongly affected by linguistic categories for stimuli presented to the right visual field than…

  15. The Effects of Color to the Eye and its Importance for Heliport Lighting

    DTIC Science & Technology

    1996-08-01

    understanding of the anatomy of the eye is needed because our perception of color, and its effect on our visual and neural systems, begins as light...Handbook of Sensory Phisiology ,Vol. 11/4. New York: Springer, Verlay. (1972). Nagy, Allen L. and Robert R. Sanchez. "Critical Color Differences

  16. The Colors of 'Endurance'

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This false-color image shows visible mineral changes between the materials that make up the rim of the impact crater known as 'Endurance.' The image was taken by the panoramic camera on NASA's Mars Exploration Rover Opportunity using all 13 color filters. The cyan blue color denotes basalts, whereas the dark green color denotes a mixture of iron oxide and basaltic materials. Reds and yellows indicate dusty material containing sulfates. Scientists are very interested in exploring the interior and exterior material around the crater's rim for clues to the processes that formed the crater, as well as the rocks and textures that define the crater.

  17. Universality of color names.

    PubMed

    Lindsey, Delwin T; Brown, Angela M

    2006-10-31

    We analyzed the World Color Survey (WCS) color-naming data set by using k-means cluster and concordance analyses. Cluster analysis relied on a similarity metric based on pairwise Pearson correlation of the complete chromatic color-naming patterns obtained from individual WCS informants. When K, the number of k-means clusters, varied from 2 to 10, we found that (i) the average color-naming patterns of the clusters all glossed easily to single or composite English patterns, and (ii) the structures of the k-means clusters unfolded in a hierarchical way that was reminiscent of the Berlin and Kay sequence of color category evolution. Gap statistical analysis showed that 8 was the optimal number of WCS chromatic categories: RED, GREEN, YELLOW-OR-ORANGE, BLUE, PURPLE, BROWN, PINK, and GRUE (GREEN-OR-BLUE). Analysis of concordance in color naming within WCS languages revealed small regions in color space that exhibited statistically significantly high concordance across languages. These regions agreed well with five of six primary focal colors of English. Concordance analysis also revealed boundary regions of statistically significantly low concordance. These boundary regions coincided with the boundaries associated with English WARM and COOL. Our results provide compelling evidence for similarities in the mechanisms that guide the lexical partitioning of color space among WCS languages and English.

  18. Crater Floor in Color

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 5 May 2004 This daytime visible color image was collected on November 18, 2003 during the Southern Summer season in Terra Cimmeria.

    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 -23.7, Longitude 135.6 East (224.4 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

  19. Experiences of Differential Treatment among College Students of Color.

    ERIC Educational Resources Information Center

    Suarez-Balcazar, Yolanda; Orellana-Damacela, Lucia; Portillo, Nelson; Rowan, Jean M.; Andrews-Guillen, Chelsea

    2003-01-01

    Studied perceptions of differential treatment of students of color through surveys completed by Caucasian (n=500) and non-Caucasian (n=495) college students. Findings show African Americans experienced more incidents of differential treatment in peer-faculty situations and females rated higher both the degree of offensiveness and degree of…

  20. Luminance contours can gate afterimage colors and "real" colors.

    PubMed

    Anstis, Stuart; Vergeer, Mark; Van Lier, Rob

    2012-09-06

    It has long been known that colored images may elicit afterimages in complementary colors. We have already shown (Van Lier, Vergeer, & Anstis, 2009) that one and the same adapting image may result in different afterimage colors, depending on the test contours presented after the colored image. The color of the afterimage depends on two adapting colors, those both inside and outside the test. Here, we further explore this phenomenon and show that the color-contour interactions shown for afterimage colors also occur for "real" colors. We argue that similar mechanisms apply for both types of stimulation.

  1. Auto white balance method using a pigmentation separation technique for human skin color

    NASA Astrophysics Data System (ADS)

    Tanaka, Satomi; Kakinuma, Akihiro; Kamijo, Naohiro; Takahashi, Hiroshi; Tsumura, Norimichi

    2017-02-01

    The human visual system maintains the perception of colors of an object across various light sources. Similarly, current digital cameras feature an auto white balance function, which estimates the illuminant color and corrects the color of a photograph as if the photograph was taken under a certain light source. The main subject in a photograph is often a person's face, which could be used to estimate the illuminant color. However, such estimation is adversely affected by differences in facial colors among individuals. The present paper proposes an auto white balance algorithm based on a pigmentation separation method that separates the human skin color image into the components of melanin, hemoglobin and shading. Pigment densities have a uniform property within the same race that can be calculated from the components of melanin and hemoglobin in the face. We, thus, propose a method that uses the subject's facial color in an image and is unaffected by individual differences in facial color among Japanese people.

  2. The effect of appropriate and inappropriate stimulus color on odor discrimination.

    PubMed

    Stevenson, Richard J; Oaten, Megan

    2008-05-01

    Color can strongly affect participants' self-report of an odor's qualities. In Experiment 1, we examined whether color influences a more objective measure of odor quality, discrimination. Odor pairs, presented in their appropriate color (e.g., strawberry and cherry in red water), an inappropriate color (e.g., strawberry and cherry in green water), or uncolored water were presented for discrimination. Participants made significantly more errors when odors were discriminated in an inappropriate color. In Experiment 2, the same design was utilized, but with an articulatory suppression task (AST), to examine whether the effect of color was mediated by identification or by a more direct effect on the percept. Here, the AST significantly improved discrimination for the inappropriate color condition, relative to Experiment 1. Although color does affect a more objective measure of odor quality, this is mediated by conceptual, rather than perceptual, means.

  3. The face-selective N170 component is modulated by facial color.

    PubMed

    Nakajima, Kae; Minami, Tetsuto; Nakauchi, Shigeki

    2012-08-01

    Faces play an important role in social interaction by conveying information and emotion. Of the various components of the face, color particularly provides important clues with regard to perception of age, sex, health status, and attractiveness. In event-related potential (ERP) studies, the N170 component has been identified as face-selective. To determine the effect of color on face processing, we investigated the modulation of N170 by facial color. We recorded ERPs while subjects viewed facial color stimuli at 8 hue angles, which were generated by rotating the original facial color distribution around the white point by 45° for each human face. Responses to facial color were localized to the left, but not to the right hemisphere. N170 amplitudes gradually increased in proportion to the increase in hue angle from the natural-colored face. This suggests that N170 amplitude in the left hemisphere reflects processing of facial color information.

  4. Auto white balance method using a pigmentation separation technique for human skin color

    NASA Astrophysics Data System (ADS)

    Tanaka, Satomi; Kakinuma, Akihiro; Kamijo, Naohiro; Takahashi, Hiroshi; Tsumura, Norimichi

    2016-11-01

    The human visual system maintains the perception of colors of an object across various light sources. Similarly, current digital cameras feature an auto white balance function, which estimates the illuminant color and corrects the color of a photograph as if the photograph was taken under a certain light source. The main subject in a photograph is often a person's face, which could be used to estimate the illuminant color. However, such estimation is adversely affected by differences in facial colors among individuals. The present paper proposes an auto white balance algorithm based on a pigmentation separation method that separates the human skin color image into the components of melanin, hemoglobin and shading. Pigment densities have a uniform property within the same race that can be calculated from the components of melanin and hemoglobin in the face. We, thus, propose a method that uses the subject's facial color in an image and is unaffected by individual differences in facial color among Japanese people.

  5. Ocean color imagery: Coastal zone color scanner

    NASA Technical Reports Server (NTRS)

    Hovis, W. A.

    1975-01-01

    Investigations into the feasibility of sensing ocean color from high altitude for determination of chlorophyll and sediment distributions were carried out using sensors on NASA aircraft, coordinated with surface measurements carried out by oceanographic vessels. Spectrometer measurements in 1971 and 1972 led to development of an imaging sensor now flying on a NASA U-2 and the Coastal Zone Color Scanner to fly on Nimbus G in 1978. Results of the U-2 effort show the imaging sensor to be of great value in sensing pollutants in the ocean.

  6. Polar Cap Colors

    NASA Technical Reports Server (NTRS)

    2004-01-01

    [figure removed for brevity, see original site]

    Released 12 May 2004 This daytime visible color image was collected on June 6, 2003 during the Southern Spring season near the South Polar Cap Edge.

    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 -77.8, Longitude 195 East (165 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

  7. Navigation lights color study

    NASA Astrophysics Data System (ADS)

    Barbosa, Jose G.; Alberg, Matthew T.

    2015-05-01

    The chromaticity of navigation lights are defined by areas on the International Commission on Illumination (CIE) 1931 chromaticity diagram. The corner coordinates for these areas are specified in the International Regulations for Prevention of Collisions at Sea, 1972 (72 COLREGS). The navigation light's color of white, red, green, and yellow are bounded by these areas. The chromaticity values specified by the COLREGS for navigation lights were intended for the human visual system (HVS). The HVS can determine the colors of these lights easily under various conditions. For digital color camera imaging systems the colors of these lights are dependent on the camera's color spectral sensitivity, settings, and color correction. At night the color of these lights are used to quickly determine the relative course of vessels. If these lights are incorrectly identified or there is a delay in identifying them this could be a potential safety of ship concern. Vessels that use camera imaging systems exclusively for sight, at night, need to detect, identify, and discriminate navigation lights for navigation and collision avoidance. The introduction of light emitting diode (LED) lights and lights with different spectral signatures have the potential to be imaged very differently with an RGB color filter array (CFA) color camera than with the human eye. It has been found that some green navigation lights' images appear blue verse green. This has an impact on vessels that use camera imaging systems exclusively for navigation. This paper will characterize color cameras ability to properly reproducing navigation lights' color and survey a set of navigation light to determine if they conform to the COLREGS.

  8. The Achromatic Light Curve of the Optical Afterglow of GRB 030226 at a Redshift of z Approximately 2

    NASA Technical Reports Server (NTRS)

    Klose, S.; Greiner, J.; Rau, A.; Henden, A. A.; Hartmann, D. H.; Zeh, A.; Masetti, N.; Guenther, E.; Stecklum, B.; Lindsay, K.

    2003-01-01

    Abstract. We report on optical and near-infrared (NIR) follow-up observations of the afterglow of GRB 030226, mainly performed with the telescopes at ESO La Silla and Paranal, with additional data obtained at other places. Our first observations started 0.2 days after the burst when the afterglow was at a magnitude of R approximately equal to 19 . One week later the magnitude of the afterglow had fallen to R=25, and at two weeks after the burst it could no longer be detected (R > 26). Our VLT blueband spectra show two absorption line systems at redshifts z = 1.962 +/- 0.001 and at z = 1.986 +/- 0.001, placing the redshift of the burster close to 2. Within our measurement errors no evidence for variations in the line strengths has been found between 0.2 and 1.2 days after the burst. An overabundance of alpha-group elements might indicate that the burst occurred in a chemically young interstellar region shaped by the nucleosynthesis from type II supernovae. The spectral slope of the afterglow shows no signs for cosmic dust along the line of sight in the GRB host galaxy, which itself remained undetected (R > 26.2). At the given redshift no supernova component affected the light from the GRB afterglow, so that the optical transient was essentially only powered by the radiation from the GRB fireball, allowing for a detailed investigation of the color evolution of the afterglow light. In our data set no obvious evidence for color changes has been found before, during, or after the smooth break in the light curve approximately 1 day after the burst. In comparison with investigations by others, our data favor the interpretation that the afterglow began to develop into a homogeneous interstellar medium before the break in the light curve became apparent.

  9. 3-D Color Wheels

    ERIC Educational Resources Information Center

    DuBois, Ann

    2010-01-01

    The blending of information from an academic class with projects from art class can do nothing but strengthen the learning power of the student. Creating three-dimensional color wheels provides the perfect opportunity to combine basic geometry knowledge with color theory. In this article, the author describes how her seventh-grade painting…

  10. Drawing Color Lines.

    ERIC Educational Resources Information Center

    Gude, Olivia

    2000-01-01

    Addresses the teaching of color symbolism and asserts that racism is embodied and perpetuated through conventional notions of black and white symbolism. Discusses a project with two eighth grade classes, focusing on the discussion of color symbolism in school and popular culture. Considers the importance of analyzing contemporary languages of…

  11. A Semester of Color

    ERIC Educational Resources Information Center

    Rabinovitch, Andrea

    2006-01-01

    Every Thursday evening, ten high school students meet at the Riverdale Art Project, a New York City-based art program that the author co-founded ten years ago. Students are participating in a semester-long color workshop where they learn about color theory in a structured and engaging way. Focusing on five essential characteristics of color…

  12. 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…

  13. Disabled Students of Color.

    ERIC Educational Resources Information Center

    Frank, Zelma Lloyd; Ball-Brown, Brenda

    1993-01-01

    Explores why few disabled students of color use student services. Details why some of these students were unnecessarily placed in special education programs and focuses on the experiences of this group. Addresses general cultural differences that can affect responses between people of color and disability services. Provides guidelines for service…

  14. Plasmonic color tuning

    NASA Astrophysics Data System (ADS)

    Lee, Byoungho; Yun, Hansik; Lee, Seung-Yeol; Kim, Hwi

    2016-03-01

    In general, color filter is an optical component to permit the transmission of a specific color in cameras, displays, and microscopes. Each filter has its own unchangeable color because it is made by chemical materials such as dyes and pigments. Therefore, in order to express various colorful images in a display, one pixel should have three sub-pixels of red, green, and blue colors. Here, we suggest new plasmonic structure and method to change the color in a single pixel. It is comprised of a cavity and a metal nanoaperture. The optical cavity generally supports standing waves inside it, and various standing waves having different wavelength can be confined together in one cavity. On the other hand, although light cannot transmit sub-wavelength sized aperture, surface plasmons can propagate through the metal nanoaperture with high intensity due to the extraordinary transmission. If we combine the two structures, we can organize the spatial distribution of amplitudes according to wavelength of various standing waves using the cavity, and we can extract a light with specific wavelength and amplitude using the nanoaperture. Therefore, this cavity-aperture structure can simultaneously tune the color and intensity of the transmitted light through the single nanoaperture. We expect that the cavity-apertures have a potential for dynamic color pixels, micro-imaging system, and multiplexed sensors.

  15. Color quality scale

    NASA Astrophysics Data System (ADS)

    Davis, Wendy; Ohno, Yoshi

    2010-03-01

    The color rendering index (CRI) has been shown to have deficiencies when applied to white light-emitting-diode-based sources. Furthermore, evidence suggests that the restricted scope of the CRI unnecessarily penalizes some light sources with desirable color qualities. To solve the problems of the CRI and include other dimensions of color quality, the color quality scale (CQS) has been developed. Although the CQS uses many of elements of the CRI, there are a number of fundamental differences. Like the CRI, the CQS is a test-samples method that compares the appearance of a set of reflective samples when illuminated by the test lamp to their appearance under a reference illuminant. The CQS uses a larger set of reflective samples, all of high chroma, and combines the color differences of the samples with a root mean square. Additionally, the CQS does not penalize light sources for causing increases in the chroma of object colors but does penalize sources with smaller rendered color gamut areas. The scale of the CQS is converted to span 0-100, and the uniform object color space and chromatic adaptation transform used in the calculations are updated. Supplementary scales have also been developed for expert users.

  16. Colorful Underwater Sea Creatures

    ERIC Educational Resources Information Center

    McCutcheon, Heather

    2011-01-01

    In this article, the author describes a project wherein students created colorful underwater sea creatures. This project began with a discussion about underwater sea creatures and how they live. The first step was making the multi-colored tissue paper that would become sea creatures and seaweed. Once students had the shapes of their sea creatures…

  17. TOCM digital color photography

    NASA Astrophysics Data System (ADS)

    Zhang, Baoying; Mu, Guoguang; Fang, Zhiliang; Li, Zhengqun; Fang, Hui; Yang, Yong

    2009-11-01

    In this paper, total optical color modulator (TOCM) digital color photography is presented. TOCM has the character of multi-wave superposed in spatial domain and separated in frequency domain. If TOCM is close-contacted with the image plane of a black-and-white (B&W) CCD, the encoding B&W CCD is formed. Image from the encoding B&W CCD are digital encoded by the TOCM. The decoded color image can be obtained by computer program. The program includes four main steps. The first step is Fourier transforming of the encoded image. The second step is filtering the spectra of the first and zero order in frequency domain. The third is inverse Fourier transforming of the filtered spectra. The last is melting the image with zero order. Then the digital color image will be shown on the display of the computer. The experiment proves that this technique is feasible. The principle of encoding color information in B&W image can be applied to color-blind sensors to get digital color image. Furthermore, it can be applied to digital multi-spectra color photography.

  18. Image color reduction method for color-defective observers using a color palette composed of 20 particular colors

    NASA Astrophysics Data System (ADS)

    Sakamoto, Takashi

    2015-01-01

    This study describes a color enhancement method that uses a color palette especially designed for protan and deutan defects, commonly known as red-green color blindness. The proposed color reduction method is based on a simple color mapping. Complicated computation and image processing are not required by using the proposed method, and the method can replace protan and deutan confusion (p/d-confusion) colors with protan and deutan safe (p/d-safe) colors. Color palettes for protan and deutan defects proposed by previous studies are composed of few p/d-safe colors. Thus, the colors contained in these palettes are insufficient for replacing colors in photographs. Recently, Ito et al. proposed a p/dsafe color palette composed of 20 particular colors. The author demonstrated that their p/d-safe color palette could be applied to image color reduction in photographs as a means to replace p/d-confusion colors. This study describes the results of the proposed color reduction in photographs that include typical p/d-confusion colors, which can be replaced. After the reduction process is completed, color-defective observers can distinguish these confusion colors.

  19. Color spaces for color-gamut mapping

    NASA Astrophysics Data System (ADS)

    McCann, John J.

    1999-10-01

    Before doing extensive color gamut experiments, we wanted to test the uniformity of CIE L*a*b*. This paper shows surprisingly large discrepancies between CIE L*a*b* and isotropic observation-based color spaces, such as Munsell: (1) L*a*b* chroma exaggerate yellows and underestimate blues. (2) The average discrepancy between L*a*b* and ideal is 27%. (3) Chips with identical L*a*b* hue angles are not the same color. L*a*b* introduces errors larger than many gamut mapping corrections. We have isotropic data in the Munsell Book. Computers allow 3D lookup tables to convert instantly any measured L*a*b* to interpolated Munsell Book values. We call this space ML, Ma, and Mb in honor of Munsell. LUTs have been developed for both LabtoMLab and MLabtoLab. With this zero-error, isotropic space we can return our attention to the original problem of color-gamut image processing.

  20. Color vision and dentistry.

    PubMed

    Wasson, W; Schuman, N

    1992-05-01

    Color vision is a critical component of restorative and esthetic dentistry, but dentists, as a group, do not have their color vision tested at any time during their careers. A study was undertaken to ascertain the color-vision status of practicing dental personnel at the University of Tennessee, College of Dentistry. One hundred fifty individuals, 75 men and 75 women, were screened. The results corroborated the existing medical data for the general population. It was found that 9.3% of the men and none of the women exhibited color-vision defect. Since most dentists are male, this study demonstrates an area of potential weakness for some practitioners. Once a color-vision problem is found, it is simple to remedy by employing a team approach to shade matching or mechanical means of matching shades (by the practitioner). No ethnic or racial distinctions were detected, although these have been reported in other studies.

  1. Colour also matters for nocturnal birds: owlet bill coloration advertises quality and influences parental feeding behaviour in little owls.

    PubMed

    Avilés, J M; Parejo, D

    2013-10-01

    Chromatic signals of offspring quality have been shown to play a role in parent-offspring communication in diurnal birds, but are assumed to be useless in dim light conditions because colour-based discrimination probably requires more light. A major ecological and evolutionary conundrum in this scenario is why the nestlings of some nocturnal owls display colourful beaks. Here, we test the hypothesis that yellow bill coloration of owlets of the nocturnal little owl Athene noctua may function as a chromatic signal revealing to parents aspects of quality of their offspring. In a first step, we examined physical variation in bill coloration and its covariation with owlet quality. Secondly, we studied parental provisioning in relation to an experimental manipulation of bill coloration of owlets. Bills of owlets showed higher within-nest variation in yellow-red chroma than in brightness. Plasma carotenoid concentration and nestling immunological status were not associated with chromatic or achromatic features of the bill. Interestingly, however, heavier owlets displayed more yellow bills than lighter ones. The effect of bill coloration on parental favouritism changed with brood size. Parents holding large broods preferentially fed owlets with enhanced over reduced yellow bill coloration, whereas those with small broods did not significantly bias feeding in relation to owlet bill coloration. Our results, based on integration of objective spectrophotometric assessment of colour and experimental procedures, confirm that parent little owls use bill coloration to reveal information on owlet body mass to adjust their feeding strategies, thus highlighting the importance of considering potential chromatic signals for a full comprehension of parent-offspring communication processes in nocturnal bird species.

  2. Evaluation of color categorization for representing vehicle colors

    NASA Astrophysics Data System (ADS)

    Zeng, Nan; Crisman, Jill D.

    1997-02-01

    This paper evaluates the accuracy of three color categorization techniques in describing vehicles colors for a system, AutoColor, which we are developing for Intelligent Transportation Systems. Color categorization is used to efficiently represent 24-bit color images with up to 8 bits of color information. Our inspiration for color categorization is based on the fact that humans typically use only a few color names to describe the numerous colors they perceive. Our Crayon color categorization technique uses a naming scheme for digitized colors which is roughly based on human names for colors. The fastest and most straight forward method for compacting a 24-bit representation into an 8-bit representation is to use the most significant bits (MSB) to represent the colors. In addition, we have developed an Adaptive color categorization technique which can derive a set of color categories for the current imaging conditions. In this paper, we detail the three color categorization techniques, Crayon, MSB, and Adaptive, and we evaluate their performance on representing vehicle colors in our AutoColor system.

  3. Stool Color: When to Worry

    MedlinePlus

    ... to worry Yesterday, my stool color was bright green. Should I be concerned? Answers from Michael F. ... of colors. All shades of brown and even green are considered normal. Only rarely does stool color ...

  4. Interference Colors in Thin Films.

    ERIC Educational Resources Information Center

    Armstrong, H. L.

    1979-01-01

    Explains interference colors in thin films as being due to the removal, or considerable reduction, of a certain color by destructive inteference that results in the complementary color being seen. (GA)

  5. The genetics of normal and defective color vision

    PubMed Central

    Neitz, Jay; Neitz, Maureen

    2011-01-01

    The contributions of genetics research to the science of normal and defective color vision over the previous few decades are reviewed emphasizing the developments in the 25 years since the last anniversary issue of Vision Research. Understanding of the biology underlying color vision has been vaulted forward through the application of the tools of molecular genetics. For all their complexity, the biological processes responsible for color vision are more accessible than for many other neural systems. This is partly because of the wealth of genetic variations that affect color perception, both within and across species, and because components of the color vision system lend themselves to genetic manipulation. Mutations and rearrangements in the genes encoding the long, middle, and short wavelength sensitive cone pigments are responsible for color vision deficiencies and mutations have been identified that affect the number of cone types, the absorption spectrum of the pigments, the functionality and viability of the cones, and the topography of the cone mosaic. The addition of an opsin gene, as occurred in the evolution of primate color vision, and has been done in experimental animals can produce expanded color vision capacities and this has provided insight into the underlying neural circuitry. PMID:21167193

  6. Comparison of perceptual color spaces for natural image segmentation tasks

    NASA Astrophysics Data System (ADS)

    Correa-Tome, Fernando E.; Sanchez-Yanez, Raul E.; Ayala-Ramirez, Victor

    2011-11-01

    Color image segmentation largely depends on the color space chosen. Furthermore, spaces that show perceptual uniformity seem to outperform others due to their emulation of the human perception of color. We evaluate three perceptual color spaces, CIELAB, CIELUV, and RLAB, in order to determine their contribution to natural image segmentation and to identify the space that obtains the best results over a test set of images. The nonperceptual color space RGB is also included for reference purposes. In order to quantify the quality of resulting segmentations, an empirical discrepancy evaluation methodology is discussed. The Berkeley Segmentation Dataset and Benchmark is used in test series, and two approaches are taken to perform the experiments: supervised pixelwise classification using reference colors, and unsupervised clustering using k-means. A majority filter is used as a postprocessing stage, in order to determine its contribution to the result. Furthermore, a comparison of elapsed times taken by the required transformations is included. The main finding of our study is that the CIELUV color space outperforms the other color spaces in both discriminatory performance and computational speed, for the average case.

  7. Design and development of an ambient-temperature continuously-rotating achromatic half-wave plate for CMB polarization modulation on the POLARBEAR-2 experiment

    NASA Astrophysics Data System (ADS)

    Hill, Charles A.; Beckman, Shawn; Chinone, Yuji; Goeckner-Wald, Neil; Hazumi, Masashi; Keating, Brian; Kusaka, Akito; Lee, Adrian T.; Matsuda, Frederick; Plambeck, Richard; Suzuki, Aritoki; Takakura, Satoru

    2016-07-01

    We describe the development of an ambient-temperature continuously-rotating half-wave plate (HWP) for study of the Cosmic Microwave Background (CMB) polarization by the POLARBEAR-2 (PB2) experiment. Rapid polarization modulation suppresses 1/f noise due to unpolarized atmospheric turbulence and improves sensitivity to degree-angular-scale CMB fluctuations where the inflationary gravitational wave signal is thought to exist. A HWP modulator rotates the input polarization signal and therefore allows a single polarimeter to measure both linear polarization states, eliminating systematic errors associated with differencing of orthogonal detectors. PB2 projects a 365-mm-diameter focal plane of 7,588 dichroic, 95/150 GHz transition-edge-sensor bolometers onto a 4-degree field of view that scans the sky at 1 degree per second. We find that a 500-mm-diameter ambient-temperature sapphire achromatic HWP rotating at 2 Hz is a suitable polarization modulator for PB2. We present the design considerations for the PB2 HWP, the construction of the HWP optical stack and rotation mechanism, and the performance of the fully-assembled HWP instrument. We conclude with a discussion of HWP polarization modulation for future Simons Array receivers.

  8. THE IMPACT OF THE SPECTRAL RESPONSE OF AN ACHROMATIC HALF-WAVE PLATE ON THE MEASUREMENT OF THE COSMIC MICROWAVE BACKGROUND POLARIZATION

    SciTech Connect

    Bao, C.; Gold, B.; Hanany, S.; Baccigalupi, C.; Leach, S.; Didier, J.; Johnson, B. R.; Miller, A.; Jaffe, A.; O'Dea, D.; Matsumura, T.

    2012-03-10

    We study the impact of the spectral dependence of the linear polarization rotation induced by an achromatic half-wave plate on measurements of cosmic microwave background polarization in the presence of astrophysical foregrounds. We focus on the systematic effects induced on the measurement of inflationary gravitational waves by uncertainties in the polarization and spectral index of Galactic dust. We find that for the experimental configuration and noise levels of the balloon-borne EBEX experiment, which has three frequency bands centered at 150, 250, and 410 GHz, a crude dust subtraction process mitigates systematic effects to below detectable levels for 10% polarized dust and tensor-to-scalar ratio of as low as r = 0.01. We also study the impact of uncertainties in the spectral response of the instrument. With a top-hat model of the spectral response for each band, characterized by band center and bandwidth, and with the same crude dust subtraction process, we find that these parameters need to be determined to within 1 and 0.8 GHz at 150 GHz; 9 and 2.0 GHz at 250 GHz; and 20 and 14 GHz at 410 GHz, respectively. The approach presented in this paper is applicable to other optical elements that exhibit polarization rotation as a function of frequency.

  9. A Hybrid Reflective/Refractive/Diffractive Achromatic Fiber-Coupled Radiation Resistant Imaging System for Use in the Spallation Neutron Source (SNS)

    SciTech Connect

    Maxey, L Curt; Ally, Tanya R; Brunson, Aly; Garcia, Frances; Goetz, Kathleen C; Hasse, Katelyn E; McManamy, Thomas J; Shea, Thomas J; Simpson, Marc Livingstone

    2011-01-01

    A fiber-coupled imaging system for monitoring the proton beam profile on the target of the Spallation Neutron Source was developed using reflective, refractive and diffractive optics to focus an image onto a fiber optic imaging bundle. The imaging system monitors the light output from a chromium-doped aluminum oxide (Al{sub 2}0{sub 3}:Cr) scintillator on the nose of the target. Metal optics are used to relay the image to the lenses that focus the image onto the fiber. The material choices for the lenses and fiber were limited to high-purity fused silica, due to the anticipated radiation dose of 10{sup 8} R. In the first generation system (which had no diffractive elements), radiation damage to the scintillator on the nose of the target significantly broadened the normally monochromatic (694 nm) spectrum. This created the need for an achromatic design in the second generation system. This was achieved through the addition of a diffractive optic for chromatic correction. An overview of the target imaging system and its performance, with particular emphasis on the design and testing of a hybrid refractive/diffractive high-purity fused silica imaging triplet, is presented.

  10. False Color Terrain Model of Phoenix Workspace

    NASA Technical Reports Server (NTRS)

    2008-01-01

    This is a terrain model of Phoenix's Robotic Arm workspace. It has been color coded by depth with a lander model for context. The model has been derived using images from the depth perception feature from Phoenix's Surface Stereo Imager (SSI). Red indicates low-lying areas that appear to be troughs. Blue indicates higher areas that appear to be polygons.

    The Phoenix Mission is led by the University of Arizona, Tucson, on behalf of NASA. Project management of the mission is by NASA's Jet Propulsion Laboratory, Pasadena, Calif. Spacecraft development is by Lockheed Martin Space Systems, Denver.

  11. Color categories are not universal: new evidence from traditional and western cultures

    NASA Astrophysics Data System (ADS)

    Roberson, Debi D.; Davidoff, Jules; Davies, Ian R. L.

    2002-06-01

    Evidence presented supports the linguistic relativity of color categories in three different paradigms. Firstly, a series of cross-cultural investigations, which had set out to replicate the seminal work of Rosch Heider with the Dani of New Guinea, failed to find evidence of a set of universal color categories. Instead, we found evidence of linguistic relativity in both populations tested. Neither participants from a Melanesian hunter-gatherer culture, nor those from an African pastoral tribe, whose languages both contain five color terms, showed a cognitive organization of color resembling that of English speakers. Further, Melanesian participants showed evidence of Categorical Perception, but only at their linguistic category boundaries. Secondly, in native English speakers verbal interference was found to selectively remove the defining features of Categorical Perception. Under verbal interference, the greater accuracy normally observed for cross-category judgements compared to within-category judgements disappeared. While both visual and verbal codes may be employed in the recognition memory of colors, participants only make use of verbal coding when demonstrating Categorical Perception. Thirdly, in a brain- damaged patient suffering from a naming disorder, the loss of labels radically impaired his ability to categorize colors. We conclude that language affects both the perception of and memory for colors.

  12. Stork Color Proofing Technology

    NASA Astrophysics Data System (ADS)

    Ekman, C. Frederick

    1989-04-01

    For the past few years, Stork Colorproofing B.V. has been marketing an analog color proofing system in Europe based on electrophoto-graphic technology it pioneered for the purpose of high resolution, high fidelity color imaging in the field of the Graphic Arts. Based in part on this technology, it will make available on a commercial basis a digital color proofing system in 1989. Proofs from both machines will provide an exact reference for the user and will look, feel, and behave in a reproduction sense like the printed press sheet.

  13. Colors on Jupiter

    NASA Technical Reports Server (NTRS)

    Owen, T.; Terrile, R. J.

    1981-01-01

    The colors present in the clouds of Jupiter at the time of the Voyager encounters are described as they appear in high resolution images. It is shown that latitude, altitude and dwelltime are all critical factors in determining which colors appear where, although the identities of the responsible chromophores remain unestablished. Simultaneous ground-based 5 micron observations are used to determine the relative altitudes of the cloud systems which are characterized as white clouds, tawny clouds, dark brown cloud belts, and blue-grey hot spots in equatorial regions. Correlations between cloud color and certain latitudes have been maintained for decades, which suggests the importance of the internal energy source.

  14. Colors and contact dermatitis.

    PubMed

    Bonamonte, Domenico; Foti, Caterina; Romita, Paolo; Vestita, Michelangelo; Angelini, Gianni

    2014-01-01

    The diagnosis of skin diseases relies on several clinical signs, among which color is of paramount importance. In this review, we consider certain clinical presentations of both eczematous and noneczematous contact dermatitis in which color plays a peculiar role orientating toward the right diagnosis. The conditions that will be discussed include specific clinical-morphologic subtypes of eczematous contact dermatitis, primary melanocytic, and nonmelanocytic contact hyperchromia, black dermographism, contact chemical leukoderma, and others. Based on the physical, chemical, and biologic factors underlying a healthy skin color, the various skin shades drawing a disease picture are thoroughly debated, stressing their etiopathogenic origins and histopathologic aspects.

  15. Difference in color and color parameters between dental porcelain and porcelain-repairing resin composite.

    PubMed

    Kim, Sung-Hee; Lee, Yong-Keun; Lim, Bum-Soon; Rhee, Sang-Hoon; Yang, Hyeong-Cheol

    2006-01-01

    The objective of this study was to measure the differences in color and color parameters between dental porcelain and porcelain-repairing resin composites. The colors of three shades (A2, A3, A3.5) of one brand of dental porcelain, three original shades (A2, A3, A3.5), and three combinations (A2/A3, A3/3.5, A2/A3.5) of three brands of porcelain-repairing resin composites (ABT, FSP, TCR) were measured. The specimens were 2 mm thick, and 1 mm of each shade was layered to make combined shades. Differences in color (DeltaE(ab) (*)), lightness (DeltaL*), chroma (DeltaC(ab) (*)), and hue (DeltaH(*)) between porcelain and resin composite were calculated. Color difference was calculated as DeltaE(ab) (*) = (DeltaL*(2) + Deltaa*(2) + Deltab*(2))(1/2), chroma difference was calculated as DeltaC(ab) (*) = (Deltaa*(2) + Deltab*(2))(1/2), and hue difference was calculated as DeltaH(ab) (*) = (DeltaE(ab) (*2) - DeltaL*(2) - DeltaC(ab) (*2))(1/2). The influence of porcelain shade, brand of resin composites, and shade of resin composites were analyzed by three-way analyses of variance, and the differential influence of color parameters on color difference was analyzed with multiple regression analysis (alpha = 0.05). Differences in color and color parameters were influenced by the porcelain shade, brand and shade of resin composites. The DeltaE(ab) (*) value was in the range of 2.2-16.9. The DeltaE(ab) (*) value was correlated with DeltaC(ab) (*) (standardized correlation coefficient, beta = - 0.85), DeltaL* (beta = - 0.52), and DeltaH(ab) (*) (beta = 0.08). Between the same shade designated pairs of porcelain and repairing composite, color difference was perceptible. Therefore, studies to improve the color matching between porcelain and repairing resin are recommended.

  16. Creating Colored Letters: Familial Markers of Grapheme-Color Synesthesia in Parietal Lobe Activation and Structure.

    PubMed

    Colizoli, Olympia; Murre, Jaap M J; Scholte, H Steven; Rouw, Romke

    2017-02-14

    Perception is inherently subjective, and individual differences in phenomenology are well illustrated by the phenomenon of synesthesia (highly specific, consistent, and automatic cross-modal experiences, in which the external stimulus corresponding to the additional sensation is absent). It is unknown why some people develop synesthesia and others do not. In the current study, we tested whether neural markers related to having synesthesia in the family were evident in brain function and structure. Relatives of synesthetes (who did not have any type of synesthesia themselves) and matched controls read specially prepared books with colored letters for several weeks and were scanned before and after reading using magnetic resonance imaging. Effects of acquired letter-color associations were evident in brain activation. Training-related activation (while viewing black letters) in the right angular gyrus of the parietal lobe was directly related to the strength of the learned letter-color associations (behavioral Stroop effect). Within this obtained angular gyrus ROI, the familial trait of synesthesia related to brain activation differences while participants viewed both black and colored letters. Finally, we compared brain structure using voxel-based morphometry and diffusion tensor imaging to test for group differences and training effects. One cluster in the left superior parietal lobe had significantly more coherent white matter in the relatives compared with controls. No evidence for experience-dependent plasticity was obtained. For the first time, we present evidence suggesting that the (nonsynesthete) relatives of grapheme-color synesthetes show atypical grapheme processing as well as increased brain connectivity.

  17. Coherent modulation of stimulus colour can affect visually induced self-motion perception.

    PubMed

    Nakamura, Shinji; Seno, Takeharu; Ito, Hiroyuki; Sunaga, Shoji

    2010-01-01

    The effects of dynamic colour modulation on vection were investigated to examine whether perceived variation of illumination affects self-motion perception. Participants observed expanding optic flow which simulated their forward self-motion. Onset latency, accumulated duration, and estimated magnitude of the self-motion were measured as indices of vection strength. Colour of the dots in the visual stimulus was modulated between white and red (experiment 1), white and grey (experiment 2), and grey and red (experiment 3). The results indicated that coherent colour oscillation in the visual stimulus significantly suppressed the strength of vection, whereas incoherent or static colour modulation did not affect vection. There was no effect of the types of the colour modulation; both achromatic and chromatic modulations turned out to be effective in inhibiting self-motion perception. Moreover, in a situation where the simulated direction of a spotlight was manipulated dynamically, vection strength was also suppressed (experiment 4). These results suggest that observer's perception of illumination is critical for self-motion perception, and rapid variation of perceived illumination would impair the reliabilities of visual information in determining self-motion.

  18. Multiple Redundant Medulla Projection Neurons Mediate Color Vision in Drosophila

    PubMed Central

    Melnattur, Krishna V.; Pursley, Randall; Lin, Tzu-Yang; Ting, Chun-Yuan; Smith, Paul D.; Pohida, Thomas; Lee, Chi-Hon

    2014-01-01

    The receptor mechanism for color vision has been extensively studied. In contrast, the circuit(s) that transform(s) photoreceptor signals into color percepts to guide behavior remain(s) poorly characterized. Using intersectional genetics to inactivate identified subsets of neurons, we have uncovered the first-order interneurons that are functionally required for hue discrimination in Drosophila. We developed a novel aversive operant conditioning assay for intensity independent color discrimination (true color vision) in Drosophila. Single flying flies are magnetically tethered in an arena surrounded by blue and green LEDs. The flies’ optomotor response is used to determine the blue-green isoluminant intensity. Flies are then conditioned to discriminate between equiluminant blue or green stimuli. Wild-type flies are successfully trained in this paradigm when conditioned to avoid either blue or green. Functional color entrainment requires the function of the narrow spectrum photoreceptors R8 and/or R7, and is within a limited range, intensity independent, suggesting that it is mediated by a color vision system. The medulla projection neurons, Tm5a/b/c and Tm20, receive direct inputs from R7 or R8 photoreceptors and indirect input from the broad spectrum photoreceptors R1-R6 via the lamina neuron L3. Genetically inactivating these four classes of medulla projection neurons abolished color learning. However, inactivation of subsets of these neurons is insufficient to block color learning, suggesting that true color vision is mediated by multiple redundant pathways. We hypothesize that flies represent color along multiple axes at the first synapse in the fly visual system. The apparent redundancy in learned color discrimination sharply contrasts with innate UV spectral preference, which is dominated by a single pathway from the amacrine neuron Dm8 to the Tm5c projection neurons. PMID:24766346

  19. Multiple redundant medulla projection neurons mediate color vision in Drosophila.

    PubMed

    Melnattur, Krishna V; Pursley, Randall; Lin, Tzu-Yang; Ting, Chun-Yuan; Smith, Paul D; Pohida, Thomas; Lee, Chi-Hon

    2014-01-01

    The receptor mechanism for color vision has been extensively studied. In contrast, the circuit(s) that transform(s) photoreceptor signals into color percepts to guide behavior remain(s) poorly characterized. Using intersectional genetics to inactivate identified subsets of neurons, we have uncovered the first-order interneurons that are functionally required for hue discrimination in Drosophila. We developed a novel aversive operant conditioning assay for intensity-independent color discrimination (true color vision) in Drosophila. Single flying flies are magnetically tethered in an arena surrounded by blue and green LEDs (light-emitting diodes). The flies' optomotor response is used to determine the blue-green isoluminant intensity. Flies are then conditioned to discriminate between equiluminant blue or green stimuli. Wild-type flies are successfully trained in this paradigm when conditioned to avoid either blue or green. Functional color entrainment requires the function of the narrow-spectrum photoreceptors R8 and/or R7, and is within a limited range, intensity independent, suggesting that it is mediated by a color vision system. The medulla projection neurons, Tm5a/b/c and Tm20, receive direct inputs from R7 or R8 photoreceptors and indirect input from the broad-spectrum photoreceptors R1-R6 via the lamina neuron L3. Genetically inactivating these four classes of medulla projection neurons abolished color learning. However, inactivation of subsets of these neurons is insufficient to block color learning, suggesting that true color vision is mediated by multiple redundant pathways. We hypothesize that flies represent color along multiple axes at the first synapse in the fly visual system. The apparent redundancy in learned color discrimination sharply contrasts with innate ultraviolet (UV) spectral preference, which is dominated by a single pathway from the amacrine neuron Dm8 to the Tm5c projection neurons.

  20. A new method for colors characterization of colored stainless steel using CIE and Munsell color systems

    NASA Astrophysics Data System (ADS)

    Ji, Keming; Xue, Yongqiang; Cui, Zixiang

    2015-09-01

    It is important to establish an accurate and comprehensive method of characterizing colors of colored stainless steel and understand the changing mechanism and the regularity of colors for the research, production and application of colored stainless steel. In this work, the method which combines reflectance-wavelength with both CIE and Munsell color systems is studied, the changing regularity of hue, brightness and saturation with increasing coloring potential differences is investigated, and the mechanism of color changing is discussed. The results show that by using this method the colors of colored stainless steel can be accurately and comprehensively characterized; with coloring potential differences and colored film thickness increasing, the peaks and troughs of the reflectance curves in visible region move toward long wave, causing the cyclically changing of hue and brightness; the amplitude of reflectance curves increases, resulting in growing of the saturation; the CIE 1931 coordinate curve of colors counterclockwise and cyclically changes around the equal energy light spot.