bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantification of illuminant metamerism for four coloration systems via metameric mismatch gamuts
Authors: Berns Roy S. , Fairchild Mark D. , Beering Michael M. 
Published: June 2007

AbstractIlluminant metamerism was evaluated by generating achromatic metamers for an acrylic‐enamel coating, an acrylobutadiene styrene polymer, a polyester textile, and a nylon textile using computer colorant formulation techniques. The tristimulus matching algorithm used to generate the metamers was based on Kubelka‐Munk turbid media theory. By definition, each set of metamers that were formulated to match under CIE illuminant D65 for the 1964 CIE standard observer would mismatch under a test illuminant, forming a gamut of colorimetric coordinates. These metameric mismatch gamuts were evaluated quantitatively using multivariate statistics. Illuminants A, F2, and F11, representing incandescent, cool‐white fluorescent, and narrow‐band fluorescent, respectively, were used as test illuminants. Illuminant similarities, coloration system similarities, tristimulus variability, and reference illuminant selection criteria were evaluated.
Spectral tuning of opponent pathways is temporally dependent
Authors: Finkelstein Marcia A. 
Published: June 2007

AbstractPsychophysical test and field sensitivity data suggest that the spectral sensitivities of red/green opponent channels (red/green cells) become progressively nonopponent with decreases in stimulus size or duration. Recent data show that the shape of the field sensitivity depends not on field size per se but on the relative size of test and field. The present study examined the effect on field sensitivity of variations in the temporal parameters of stimulation. The results suggest a more complicated interaction than is observed in the spatial domain. Spectral tuning depends not only on the relative durations of test and field but also on the offset asynchrony between the two lights. Only when the test is extinguished prior to the field do the data show evidence of red/green activity. When the two lights coterminate. the field sensitivity resembles a nonopponent function, regardless of stimulus duration.
Chromatic adaptation on the minimally distinct border and brightness matching in color‐normals and deuteranopes
Authors: Hibino Haruo , Oyama Tadasu 
Published: June 2007

AbstractWe examined the effect of monochromatic adapting lights on minimally distinct border (MDB) settings and brightness matching (BM) between monochromatic test and reference fields by using three color‐normals and three deuteranopes as observers. In the case of MDB, for color‐normal observers chromatic adaptation appeared prominetly in the wavelength regions near the test and reference wavelengths in the corresponding field, when either the test or reference field was in the long‐wavelenth region. No differential effect was found for deuteranopic observers. Using BM instead of MDB, the differential effects of chromatic adaptation appeared more prominently in the short‐wavelength region for both types of observers (especially for color‐normals) and in the middle‐wavelength region for color‐normal observers. The results indicate that the blue‐sen‐sitive mechanisms make either little or no contribution to the MDB criterion, or the distinctness of borders.
Performance testing of color‐difference metrics using a color tolerance dataset
Authors: Alman David H. , Berns Roy S. , Snyder Gregory D. , Larsen Wayne A. 
Published: June 2007

AbstractA color‐difference dataset was developed for testing the performance of color metrics. The dataset comprises 45 color‐difference vectors varying in five directions at nine color centers under conditions typical of commercial color decisions. Probit analysis was used to estimate the parameters of the population distribution of tolerances for each vector. In addition to estimating the median tolerance, the anlysis allows one to estimate the uncertainty of a tolerance and to test the adequacy of the underlying model tolerance distribution. The median tolerances were used to specify 45 color‐difference pairs with equal visual color‐difference magnitudes. The performance of eight color‐difference metrics was compared using the normalized standard deviation of the color differences of the visually equal difference pairs as a measure of uniformity. A bootstrap statistical technique was used to quantify the variation in performance with varying samples of color centers and color‐difference directions and to determine the significance of observed differences in uniformity performance. Some metrics based on weighted CIELAB dl*, dC*, dH* color‐difference components had significantly superior performance compared to the CIE recommended color‐difference metrics.
Color vision model of macLeod and Boynton
Authors: Fry Glenn A. 
Published: June 2007

AbstractMacLeod and Boynton started off with the assumption that the fundamental blue falls on the x' axis of Judd's 1951 chromaticity diagram. This leads to a constant luminance diagram in which the lines that converge at the fundamental blue in Judd's diagram are parallel. MacLeod and Boynton tried to solve this problem by a slight change in one of the constants in the transformation equations. It turns out that what this does is to shift the position of the alychne on Judd's diagram so that it does not coincide with the x' axis. The blue fundamental no longer lies on the alychne. This makes it possible to derive a constant luminance chromaticity diagram in which the fundamental blue falls at one of the corners. After having created this new diagram, they used it to formulate a theory of color vision in which the blue cones contribute nothing to luminance. This procedure needs to be understood because it can be used to convert any theory of color vision in which all three cones contribute to luminance to one in which only two contribute to luminance. This has nothing to do with having the blue fundamental fall on the x' axis. A more serious problem is that Judd has made an error in his assessment of the luminosity coefficients and the concepts of MacLeod and Boynton need to be reformulated in terms of the CIE 1931 chromaticity diagram.
Changes in the wavelength of unique yellow with retinal angle of incidence
Authors: Geri George A. , Kandel Gillray L. , Roy Ii C. Genter , Walker Karen L. , Rowan Melena A. 
Published: June 2007

AbstractThe wavelength associated with the perception of unique yellow was determined for various retinal angles of stimulus incidence. Techniques previously used to measure the Stiles‐Crawford (SCII) hue shift as a function of retinal angle of incidence were procedurally and instrumentally complex and, as a result, data from only two observers exist in the literature. A simpler technique is used here to obtain data from six observers, two of whom showed hue shift functions qualitatively different from those previously reported. The peak locations of the four typical SCII hue shift functions were found to correlate well with the peak locations of the π4 and π5 color mechanisms previously reported for the same observers. It is argued that peak location is the most valid indicator of the relationship between the Stiles‐Crawford effects of the first (SCI) and second (SCII) kind and that common processes underlie the two effects.
Equivalent lightness of colored objects at illuminances from the scotopic to the photopic level
Authors: Ikeda Mitsuo , Huang Chian Ching , Ashizawa Shoko 
Published: June 2007

AbstractEquivalent lightness of four colored objects, blue, green, yellow, and red, was obtained for illuminance levels covering the range 0.01 to 1000 lx by brightness matching to a grey scale. Three field sizes, 20', 1° and 6° arc of visual angle, were investigated. With the smallest size, for which no rod response was expected, the equivalent lightness increased monotonically for incresing illuminance, showing the increasing effect of colorfulness upon brightness. The results obtained with the largest size showed influence from both rods and cones and were interpreted as due to two underlying lightnesses, one lightness based on the achromatic response of rods, cones, or both, and the other lightness based on the chromatic response of cones exhibited as colorfulness.
Accurate tristimulus values from spectral data
Authors: Venable William H. 
Published: June 2007

AbstractInter‐instrument color measurement errors of up to 2 CIELAB units are typically introduced in the process of numerically integrating spectrophotometric data to obtain tristimulus values. These errors arise partly from inadequacies in the definition of the tristimulus values themselves, but mainly from failing to take into account the effect the instrument function has on the spectrophotometric data. Through using precise definition of the tristimulus values and through using source‐observer weighting tables tailored to each specific instrument, it is practical to reduce this component of colorimetric error to less than 0.1 CIELAB unit for spectrophotometers with bandwidths up to 20 nm.
Color appearance under conditions of chromatic adaptation and contrast
Authors: Shevell Steven K. , Wesner Michael F. 
Published: June 2007

AbstractChromatic adaptation can significantly alter the color appearance of a light. We review measurements of changes in appearance caused by chromatic backgrounds and surrounds. Effects of long‐, middle‐ and short‐wavelength adapting lights are assessed by having observers adjust the physical light in a test patch to maintain a constant perceptual criterion: a test that appears neither reddish nor greenish. A variety of spatial and temporal stimulus configurations also is considered. An integrated account of the measurements is provided by the two‐process theory of chromatic adaptation, originally proposed by Hurvich and Jameson in 1958, which specifies an adapting light alters receptoral sensitivities and, simultaneously, contributes an additive increment to opponent chromatic responses.
The computation of color constant descriptors in chromatic images
Authors: Gershon Ron , Jepson Allan D. 
Published: June 2007

AbstractWe propose a method, based on finite‐dimensional linear models of reflection and illumination, which allows the transformation of chromatic images into color constant images. This proves to be useful in applications in which either there is no information on the illuminant present in the scene, or when such information is confounded by the existence of inter‐reflections between objects. The method proposed in this paper is aimed at computations taking place beyond the sensory level of vision systems, and may use inputs corrected by sensors (for adaptation). In contrast to previous work, we show that good results can be obtained using a 3‐receptor system and some knowledge about the spectral properties of natural materials and illuminants. In the method developed, an estimate of the illuminant in the scene is computed, which allow the computation of color constant descriptors of the pixel values in the image. In addition, we show a method of computing an estimate to the actual reflectances of the materials in the scence out of the computed color constant descriptors.
What determines crossover wavelengths of metameric pairs with three crossovers?
Authors: Berns Roy S. , Kuehni Rolf G. 
Published: June 2007

AbstractTwo matameric stimuli with identical tristimulus values must have spectral radiance distributions that cross at least three times. Many studies have shown that the crossover locations of three‐crossover metamers tend to occur in certain defined regions. This finding has led to hypotheses concerning fundamental aspects of the visual system. In the current article, calculations are reported that prove that crossover locations depend on the spectral properties of the metameric stimuli. For object colors, the spectral properties are determined by colorant obsorption bandwidths. Depending on the absorption bandwidth, crossovers can occur in nearly any region of the visible spectrum. Thus any relationship between crossover wavelengths and properties of the visual system such as maximal responsivities appears coincidental.
The munsell color system in fundamental color space
Authors: Burns Scott A. , Cohen Jozef B. , Kuznetsov Edward N. 
Published: June 2007

AbstractThe Munsell color system is investigated as a structure in fundamental color space. The entire collection of samples from the 1929 Munsell Book of Color is mapped into fundamental color space and surfaces of constant hue, value, and chroma are identified. An algorithm, based on these surfaces, is presented for estimating the Munsell specification of an arbitrary reflectance curve.
Colors do look different after a lens implant!
Authors: Granville Walter C. 
Published: June 2007

AbstractThis note describes how colors of some familiar objects and scenes shift when viewed with one of the author's eyes after a lens implant compared to the other eye without implant. Estimates of the shifts are described with common color names. Some shifts were found to be spectacular! Variations in the spectral transmission of the lens is believed to explain the shifts. Implications affecting the choice of clors for interiors, fashions, and other design uses are discussed. An appendix contains data on matches on the Glenn and D & H Color Rules.
A visual colorimeter for atmospheric research
Authors: Henry Ronald C. , Matamala Luis 
Published: June 2007

AbstractThis article describes the design, construction, and evaluation of a visual colorimeter for use in studies of color perception in the natural environment. The colorimeter is portable, has a low power consumption, and produces luminances typical of those found outdoors. An asymmetric binocular‐matching procedure is used to match the colors of natural objects. The performance of the colorimeter was tested by comparing chromaticities of matches of colored papers to spectrophotometric measurements.
Metric coefficients for chromatic discrimination of surface colors
Authors: Melgosa M. , Romero J. , Hita E. 
Published: June 2007

AbstractThe values of the coefficients of the metric tensor (g11, g22, and 2g12) have been determined graphically at any point on the CIE‐1964 chromatic diagram, by using Luo and Rigg's chromatic discrimination data. Chromatic‐discrimination thresholds obtained by this method and those predicted by the CIELUV, CIELAB; and LABNHU color‐difference formulas are compared with different sets of experimental results. The predictions made by the formulas do not fit the experimental results as well as the graphical predictions.
Industrial color difference: Progress and problems
Authors: Kuehni Rolf G. 
Published: June 2007

AbstractIn the ten years since the last Inter‐Society Color Council conference on color discrimination considerable progress in industrial color‐difference evaluation has been made. The results of a questionnaire indicated that the efforts of the CIE to make formula usage more uniform has been successful. Efforts to improve the correlation between average visual judgment and calculated color difference have also resulted in progress. Nevertheless, a considerable amount of work remains to be done regarding the mechanisms affecting color‐difference evaluation before instrumental color‐difference evaluation can become a highly reliable tool of manufacturing.
Equivalent lightness of colored objects of equal munsell chroma and of equal munsell value at various illuminances
Authors: Ikeda Mitsuo , Ashizawa Shoko 
Published: June 2007

AbstractEquivalent lightness was determined for 26 colored surfaces by heterochromatic brightness matching with a grey scale. The illuminance for observation was varied from 0.01 to 1000 lx to cover scotopic, mesopic, and photopic vision, and the equivalent lightness‐versus‐log illuminance curve was obtained for every stimulus. The shape of the curves did not change if the surfaces had the same Munsell hue and chroma. It differed significantly if they had different hues or different chroma. The curves were interpreted in terms of achromatic lightness and chromatic lightness, which are both subject to change with illuminance level. The achromatic lightness was assumed to follow the Purkinje shift and the chromatic lightness monotonically increased with illuminance. The chromatic lightness was larger for larger Munsell chroma within a single hue.
Theory of primary colors and invariant hues
Authors: Pridmore Ralph W. 
Published: June 2007

AbstractAdditive primaries or peaks of color‐matching functions are defined as peaks of complementary efficiency and of saturation per watt. These are near 447, 532, and 607 nm for all CIE illuminants. (CIE 1931 r, g, b functions peak at 447, 543, and 604 nm.) Subtractive or colorant primaries are defined as saturation minima and peaks of brightness or lightness per watt. Additive and subtractive primaries (e.g., red and cyan) are complementaries and opposites in saturation and lightness. In equal radiance color‐space the six lines of constant mean saturation are invariant hues (473, 508, 574 nm and 558 c) and their complementaries.
Quantifying colour appearance. Part II. Testing colour models performance using lutchi colour appearance data
Authors: Luo M. Ronnier , Clarke Anthony A. , Rhodes Peter A. , Schappo André , Scrivener Stephen A. R. , Tait Chris J. 
Published: June 2007

AbstractThe acquisition of the LUTCHI Colour Appearance Data has been described in Part I of this article. Having obtained the data, they were used to test the accuracy of prediction for various colour spaces and models. The results clearly indicate that Hunt's 91 model gives the best fit to the visual results of all the models studied. Hunt's 91 has been further refined to improve the fit to the colourfulness results, and this refined model has been designated Hunt‐ACAM (ACAM being the Alvey Colour Appearance Model). The error of prediction from Hunt‐ACAM is close to the typical error that is seen to occur between individuals' results and the mean visual results. This performance is considered to be very satisfactory, and the model is therefore believed to provide a reasonably accurate way of evaluating colour fidelity for various colour reproduction systems. Various chromatic‐adaptation transformations were also compared with three sets of corresponding chromaticities derived from the results of experiments conducted under four conditions of chromatic adaptation. The results are in reasonable agreement with those obtained by Helson et al. [Illum. Eng. 47, 221–233 (1952)] and Lam and Rigg [Ph.D. thesis, University of Bradford (1985)]. All results indicate that the Bradford and Hunt‐ACAM transformations perform the best and the second best, respectively, of all the selected formulae. The current CIE recommendation does not perform as well as expected.
The chevreul color system
Authors: Heila Ethel 
Published: June 2007

AbstractChevreul wished to represent in his color system every modification of color, including not only the modifications we observe from pigment mixtures but also those modifications in color that we observe in nature. The latter include the various gradations of light and shade on the surface color of objects which light enables us to perceive. A review and clarification of his color system reveals a logical correlation between these phenomena and the various scales in his color system. Studying these scales and understanding the concepts they represent can be very helpful to painters who wish to represent in their paintings objects in space and light in a naturalistic manner.
Color tolerance feasibility study comparing crt‐generated stimuli with an acrylic‐lacquer coating
Authors: Berns Roy S. 
Published: June 2007

AbstractVisual color tolerances were calculated from observations made on difference pairs around a single green color center. The comparison was made between observations done for actual acrylic‐lacquer samples and a simulation of the sample pairs on a computer‐controlled CRT display. A light booth with simulated daylight was used to illuminate the surface colors and to provide surround illumination for the CRT. The luminances of the CRT and light booth were equalized at 150 cd/m2. Fifteen observers judged color differences relative to a near‐gray anchor pair under three different conditions: CRT stimuli viewed with a dark surround, CRT stimuli viewed with a light surround generated by the light booth, and the surface colors. Probit analyses were used to transform population responses to estimates of equivalent color tolerances to the anchor pair, fiducial (confidence) limits about the tolerances, and population standard deviations. Observations were less precise (higher standard deviations) for CRT stimuli. This statistically significant difference was presumed due to differences in spatial and cognitive attributes. Despite these differences, observers' color tolerance determinations were not statistically different from one another or from previous experiments of the same color center but judged under a luminance three times higher than the current experiment. Results indicated that the experimental design was a reasonable approach to using CRT‐generated stimuli for measuring visual color tolerances in a manner that correlates to surface‐color judgments.
Formulation and testing of an incomplete‐chromatic‐adaptation model
Authors: Fairchild Mark D. 
Published: June 2007

AbstractA mathematical model of chromatic adaptation for calculating corresponding colors across changes of illumination based on the Hunt color appearance model is formulated and tested. This model consists of a modified von Kries transform that accounts for incomplete levels of adaptation. The model predicts that adaptation will be less complete as the saturation of the adapting stimulus increases and more complete as the luminance of the adapting stimulus increases. An experiment is described in which achromatic appearance is measured for various adapting conditions. The model is tested with these experimental results as well as results from another study and found to be significantly better at predicting corresponding colors than other proposed models.
Propagation of random errors in spectrophotometric colorimetry
Authors: Fairchild Mark D. , Reniff Lisa 
Published: June 2007

AbstractEvery physical quantity with an a priori range of numerical values constituting a continuum is subject to error in its measurement. It is important to report the highest amount by which any measured quantity might be in error. Optical radiation measurements are typiclly based on determination of the ratio of the instrumental reading of a calibrated standard to the instrumental reading of the test sample. There are random and systematic errors in both the instrumental readings and the calibration values. The uncertainty in a calculated value due to random error in its constituents can be determined using well known techniques of error propagation. Examples of error propagation through spectral reflectance factor measurements and colorimetric calculations are presented. The standard deviations of CIELAB coordinates for typical measurements can be as high as 0.258 due only to random errors in the calibration chain.
Efficient uniform illuminators using diffusing optics
Authors: Venable William H. 
Published: June 2007

AbstractUnless specimens are illuminated uniformly with respect to both position on the specimens and directon of incidence, reliable visual judments of and measurements of object color difference cannot be made. Devices producing illumination suitable for color difference evaluation can be made using an integrating sphere as and optical component intermediate between the primary source of light and the illuminated area. Properly designed, such sources can be as efficient as the more common sources using imaging optics. Techniques for designing such sources are described.