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1.
Ralph W. Pridmore 《Color research and application》2009,34(1):55-67
Part I of this article found, inter alia, that chroma resembles log inverted luminance. This article develops three math models of Munsell chroma and associated colorfulness from (1) inverted luminous reflectance Y, (2) inverted chromatic luminance, and (3) inverted chromatic luminance combined (over the mid‐spectrum 480–580 nm) with the unimodal curve for spectral absorptance of M cones. The first two models are simple but of limited accuracy and demonstrate that inverted luminance (of any form) cannot fully account for varying relative chroma around the hue cycle, particularly the minor minimum and maximum about 490 and 520 nm (which also feature in B:L functions). The third model is rather complex but very accurate, apparently the only accurate model of Munsell chroma or other experimentally based scales of relative chromaticness in the literature. It adjusts to any level of luminance or purity, as demonstrated for several levels. Three models of brightness (B:L ratio) for 20 field aperture colors are given, based on either Munsell chroma or log inverted chromatic luminance. The former provides two accurate and simple models of the CIE B:L function: (1) log chroma = B:L ratio ±0.1, and (2) (chroma/k)x = B:L ratio ±0.1. The latter also predicts B:L for nonspectral colors and those of lower purities, e.g., object colors. The results finally solve the relationship between brightness and chroma and demonstrate that B:L ratio (a contrast in constant luminance) arises directly from chroma (also a form of contrast in constant luminance), or the reverse. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 55–67, 2009. 相似文献
2.
In a preceding study we measured human color constancy in experimental conditions in which simulated illuminants and surface colors were varied in the chromatic domain only. Both illumination level and sample reflectance were fixed in that study. In the present study we focus on the achromatic dimension, both with respect to luminance contrast (Experiment 1) and overall illumination (Experiment 2). Sample‐to‐background contrast was varied over a two log unit range that covered both luminance decrements and increments. Illumination level was varied either for the short‐wave‐sensitive (S) cones only or for all three cone types simultaneously. Data predictions on the basis of a cone‐specific response function, derived in our preceding study, indicate that this model has difficulty in accommodating the results obtained with varying luminance contrast. However, a modified version of the response function, incorporating separate processing of color and luminance contrast, correctly predicts the data from both the present and the previous study. We also show that over a limited stimulus range our earlier response function is mathematically equivalent to Jameson and Hurvich's model of brightness contrast. The latter model, cast into a trichromatic format, performs equally well or better than our original response function, but is less accurate than our modified model. © 2005 Wiley Periodicals, Inc. Col Res Appl, 30, 172–185, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20105 相似文献
3.
L. Del Jimnez Barco J. A. Díaz J. R. Jimnez M. Rubio 《Color research and application》1995,20(6):377-387
To calibrate a CRT color monitor, several assumptions are often made about its performance, one of the most accepted being constanel channel chromaticity. However, when the measurements are taken in a extended field of CRT screen, where it is assumed that only one primary phosphor is excited, the relative spectral radiance of the other primary phosphors that are contained in that field also contributes, if the background luminance is not zero. This contribution is greater at low levels of RGB channel stimulation and would invalidate the results obtained with calibration methods based on the hypothesis of constancy of chromaticity coordinates of RGB channels. We have studied this effect on the calibration of the CRT color monitor and, as a result, we propose a calibration that takes this effect into account. to evaluate the accuracy of the method, we have calculated color differences between the chromaticity that we wanted to reproduce and the one displayed with the CIELUV color-difference formula, and the color tolerances with the line element of MacAdam ellipses. 相似文献
4.
Brightness-to-luminance (B/L) ratios based on the CIE 1924 V (λ) for 195 test stimuli equally sampled from the whole area of the CIE1976(u′, v′) chromaticity diagram were measured for four color normal observers. The results of two observers were similar to results in previous studies in that the B/L ratio increases as purity of the stimulus increases. However, the results of the other two observers showed very low B/L ratios, especially in the reddish region. The B/L ratios based on each observer's sensation luminance were also calculated. Although the contour lines of equal B/L ratio become less atypical for the latter two observers, they still showed low B/L values compared to typical results. Large individual differences of the B/L ratio in the whole area of the chromaticity diagram were indicated. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 274–287, 1998 相似文献
5.
Patrick Monnier 《Color research and application》2011,36(2):101-110
Distractor color heterogeneity refers to a condition in which a target is presented among distractors of different chromaticities. In the present study, the amount distractor color heterogeneity was varied systematically to determine how efficiently the visual system processes displays composed of search elements of multiple colors. Distractor color heterogeneity was expressed by selecting distractor chromaticities from sectors of various angles in a cone‐based normalized color space. The generalizability of the measurements was tested using two different visual search paradigms. An accuracy search task was used in which the search displays were presented as brief flashes and the dependent variable was search accuracy. A latency search task was used in which the display presentation time was under the participant's control and the dependent variable was reaction time. Compared to a homogeneous condition with distractors of a single color, distractor color heterogeneity had a deleterious effect on search performance in both paradigms. In normalized units, the measurements were similar across participants, target chromaticities, and tasks, but the same measurements expressed in non‐normalized units showed clear and systematic individual differences. © 2010 Wiley Periodicals, Inc. Col Res Appl, 2011 相似文献
6.
7.
The degree of additivity‐law failure of a mixture color consisting of two component chromatic colors has very complex characteristics depending on the used component colors and their mixing conditions. It is significantly affected by the mixture‐color chromaticity and by the brightness/luminance ratio at the chromaticity. A simple relationship was derived between the following quantities: degree of additivity‐law failure, additivity‐law luminance (luminance of the mixture color derived by postulating additivity law), and brightness/luminance ratio at the chromaticity of the mixture color. This relationship can be applied to any additivity‐law failure experiment and any formula on brightness/luminance ratio. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 185–190, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/col.10045 相似文献
8.
Ralph W. Pridmore 《Color research and application》2009,34(1):45-54
Chromatic luminance carries both wavelength and radiance of light, is the source of all psychophysical dimensions and all color attributes, and is a key to understand their relations. It has long attracted research, hindered in the past by flawed definitions of colorimetric purity (pc), remedied in a recent article. This article investigates relations between luminous reflectance Y (i.e., total luminance, chromatic plus achromatic), chromatic luminance (calculated from Y per pc), and chroma/colorfulness. Relations are clarified, illustrated by formulas and graphs including three‐dimensional schemas of luminance Y, chromatic luminance, and color solids. A useful new term, relative chromatic luminance, is introduced. Munsell chroma is shown to resemble inverted log luminance much more closely than inverted log colorimetric purity as claimed by previous researchers. The relationship is used in Part II to model chroma, colorfulness, and brightness. © 2008 Wiley Periodicals, Inc. Col Res Appl, 34, 45–54, 2009. 相似文献
9.
Taiichiro Ishida 《Color research and application》2002,27(4):252-259
To use colors properly as an aid in visual tasks, it is necessary to know how colors are identified under various illuminating environments. In this study color identification was examined under a wide range of illuminances, from photopic to mesopic levels. Fifteen subjects named a color chip using one of the preselected color terms: red, orange, yellow, yellow‐green, green, blue‐green, blue, purple, pink, brown, white, gray, and black. The 256 color chips were selected from value planes of 4, 6, and 8 of the Munsell color space. The illuminance levels tested were 1000, 10, 1, and 0.1 lx. At 1000 lx the color chips were identified consistently by each of the color terms. At 10 lx the pattern of color identification was very similar to that at 1000 lx, though the consistency of the identification evidently declined. At 1 lx great changes in color identification occurred. By 0.1 lx reliable color identification was completely lost, though blue and red responses remained. At the lower illuminances green was replaced with blue, and red, orange, and pink were frequently confused with each other. However, the border between blue and purple was almost constant. These results provide a scientific basis for the appropriate use of colors in various illuminating environments. Also, they are useful for studies in color appearance modeling. © 2002 Wiley Periodicals, Inc. Col Res Appl, 27, 252–259, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10065 相似文献
10.
Color difference calculations are usually applied to match or tolerance of small differences between large (>2°) visual fields. In contrast, we examine here the application of ultra‐large color differences to enhance conspicuousness and discriminability of small (1° subtense or smaller) visual targets, e.g., in visual information displays. We show that CIEDE2000, and color difference metrics based on the OSA Uniform Color Space and CIECAM02 are superior to CIELAB and CIELUV. Considering gray scale only, we show that Whittle's JND metric of achromatic contrast is as good as L* for this purpose, while also modeling contrast polarity and “crispening.” Furthermore, using this JND metric, we replicate Highnote's finding that elongation of small targets affects their apparent contrast. We discuss the perceived fading of color differences when targets become smaller, and suggest practical methods to mitigate the adverse effect on color conspicuousness and discriminability. © 2009 Wiley Periodicals, Inc., Col Res Appl, 2010. 相似文献
11.
Mark D. Fairchild 《Color research and application》1995,20(6):352-363
When viewing images, the relative luminance of the surround has a profound impact on the apparent contrast of the image. For this reason, photographic transparencies intended for projection in a darkened room are produced with an objective contrast substantially higher than that necessary for optimum reproduction as prints viewed in an illuminated surround. the dark surround causes the image elements to appear lighter and this effect is stronger for darker colors resulting in a loss in perceived contrast. This effect is also of great importance in deviceindependent color imaging since resultant images might be observed in a wide variety of media and viewing conditions. Research on psychophysical scaling of brightness and lightness and the effects of background and surround relative luminance on lightness and chroma is reviewed. the importance of this research for device-independent color imaging systems is described along with the prediction of these effects using the RLAB color-appearance model. Finally, experiments testing the use of RLAB and other color-appearance models in cross-media color reproduction applications are described. 相似文献
12.
Fernando Carreo Jos Miguel Ezquerro Jesús M. Zoido 《Color research and application》2006,31(6):468-474
We present an analytical method to analyze, from a theoretical point of view, the influence of color‐matching functions on the perception of luminance thresholds. We show that the thresholds depend on the spectral responsivities of each observer. We also analyze the influence of luminance level on the thresholds: a strong inter‐observer variability is found at low or moderate luminance levels (0.02 < Y < 1 ft?L) whereas at high intensities (1 < Y < 7 ft?L) the thresholds are observer‐independent. © 2006 Wiley Periodicals, Inc. Col Res Appl, 31, 468–474, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.20259 相似文献
13.
Kenjiro Hashimoto Tadashi Yano Masanori Shimizu Yoshinobu Nayatani 《Color research and application》2007,32(5):361-371
“Visual clarity” or “feeling of contrast” of object colors under illumination is affected significantly by changing color‐rendering property of light source used. Though the feeling of contrast is considered one of the most important characteristics on color‐rendering properties of light sources, it cannot be estimated adequately by using the present Ra method. The new index FCI is proposed for estimating the effect of feeling of contrast quantitatively under any light sources. The FCI is derived using a simple transformation of the gamut area, which is constituted by a specially selected four‐color combination in CIE LAB color space. The FCI correlates well with the illuminance ratio for equal feeling of contrast (or equal visual clarity) on various light sources reported so far. Using the FCI together with the present CIE Ra, the color‐rendering capability of a light source can be well clarified. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 361–371, 2007 相似文献
14.
Gunilla Derefeldt Tiina Swartling Ulf Berggrund Peter Bodrogi 《Color research and application》2004,29(1):7-19
This report surveys cognitive aspects of color in terms of behavioral, neuropsychological, and neurophysiological data. Color is usually defined as a color stimulus or as perceived color. In this article, a definition of the concept of cognitive color is formulated. To elucidate this concept, those visual tasks are described where it is relevant: in color categorization, color coding, color naming, the Stroop effect, spatial organization of colored visual objects, visual search, and color memory. © 2003 Wiley Periodicals, Inc. Col Res Appl, 29, 7–19, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/col.10209 相似文献
15.
Building upon electrophysiological recordings from the lateral geniculate nucleus (LGN) of the macaque monkey, we describe a model for neural processing of color and brightness/lightness information that starts in the cone receptors and continues in the opponent cells of the retina, LGN, and visual cortex. The excitation of the three cone types to direct stimulation by light is modified in accordance with a hyperbolic response function before providing inputs to retinal ganglion cells. Using weighted differences of such cone outputs, we simulate the responses of common types of opponent ganglion and geniculate cells to light modulation along the chromatic and luminance dimensions. Extrapolating the results of the simulation, we suggest a way in which the brain might combine inputs from the geniculate to obtain correlates of chromatic and achromatic color vision and of brightness/lightness perception. In particular, we demonstrate for the first time how combinations of “L–M” and “M–L” parvocellular ON‐ and OFF‐opponent‐cells may lead to a quantitative account of brightness and blackness scaling. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 433–443, 2008 相似文献
16.
A new proposal tentatively called “integrated photometric system” is given together with a detailed explanation of its structure. The proposal gives the following procedures: step 1 can determine CIE photometric quantities, step 2 can determine their perceived‐photometric correlates by applying the correction to the quantities derived in step 1. The present proposal solves the problem of coexistence of the two kinds of expected requirements in photometry suggested by Judd. In the present article, the formulas used in the step 2 are given only for luminous colors. The formulas for object colors will be given in a future article. Five applications of luminous colors are given for the step 2 of the proposed system. These applications will make it possible to promote the use of the proposed photometric system. © 2007 Wiley Periodicals, Inc. Col Res Appl, 32, 440–448, 2007 相似文献
17.
建立了用于电子书阅读器文字显示质量的评价方法。基于电子书材料的光谱反射率特征,结合常用阅读用照明光源光谱和人眼的光谱视见特性,定义了该类器件白场与暗场的亮度对比度CL和白场亮度YW性能参数。通过对12个产品的参数测量和主观评价实验,定义并分析了文字显示清晰度感知质量评价指数QC与CL和YW的相关性。结果表明:QC与CL和YW均有关;在线性相关的情况下即可较好地预测文字显示的清晰度感知质量。此外,采用CIELAB彩度Ca*b参数量化了电子书背景白的偏色程度,并通过主观评价实验表明,Ca*b彩度值增大会降低文字阅读的舒适度;大于6的Ca*b彩度值将使阅读产生不舒适感觉。 相似文献
18.
William A. Thornton 《Color research and application》2000,25(2):148-150
Suggested optimal “primaries” and concomitant optimal gamut for any form of device or product whose output serves as input to the normal human visual system: TV‐like images, or images reflected from illuminated hardcopy. For those devices and products using additive coloration, three spectral primaries 450–530–610 nm, and their associated gamut, are suggested as goals. For those using subtractive coloration, three reflective components, of width perhaps 50–60 nm at half‐height and peaking at the same wavelengths, are suggested. Thus, in either case, the light from each pixel of the generated color image entering the pupil of the normal human observer is composed of a mixture of that observer's prime colors. “Prime colors” are defined as usual as (a) the wavelengths marking the peaks of the three spectral sensitivities of the (trichromatic) normal human visual system, and, thus, (b) those spectral lights to which the normal human visual system responds most strongly per watt of power content input to the pupil. Spectral sensitivities of the normal human visual system are carefully distinguished from those of the CIE Standard Observers. © 2000 John Wiley & Sons, Inc. Col Res Appl, 25, 148–150, 2000 相似文献
19.
This research extends the previous RIT-DuPont research on suprathreshold color-difference tolerances in which CIELAB was sampled in a balanced factorial design to quantify global lack of visual uniformity. The current experiments sampled hue, specifically. Three complete hue circles at two lightnesses (L* = 40 and 60) and two chroma levels ( = 20 and 40) plus three of the five CIE recommended colors (red, green, blue) were scaled, visually, for hue discrimination, resulting in 39 color centers. Forty-five observers participated in a forced-choice perceptibility experiment, where the total color difference of 393 sample pairs were compared with a near-neutral anchor-pair stimulus of 1.03 A supplemental experiment was performed by 30 additional observers in order to validate four of the 39 color centers. A total of 34,626 visual observations were made under the recently established CIE recommended reference conditions defined for the CIE94 color-difference equation. The statistical method logit analysis with three-dimensional normit function was used to determine the hue discrimination for each color center. A three-dimensional analysis was required due to precision limitations of a digital printer used to produce the majority of colored samples. There was unwanted variance in lightness and chroma in addition to the required variance in hue. This statistical technique enabled estimates of only hue discrimination. The three-dimensional analysis was validated in the supplemental experiment, where automotive coatings produced with a minimum of unwanted variance yielded the same visual tolerances when analyzed using one-dimensional probit analysis. The results indicated that the hue discrimination suprathresholds of the pooled observers varied with CIELAB hue angle position. The suprathreshold also increased with the chroma position of a given color center, consistent with previous visual results. The results were compared with current color-difference formulas: CMC, BFD, and CIE94. All three formulas had statistically equivalent performance when used to predict the visual data. Given the lack of a hue-angle dependent function embedded in CIE94, it is clear from these results that neither CMC nor BFD adequately predict the visual data. Thus, these and other hue-suprathreshold data can be used to develop a new color-difference formula with superior performance to current equations. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 302–313, 1998 相似文献
20.
The relationship between lamp color characteristics and brightness perception is not well known. In this study, nine lighting environment with correlated color temperature (3000 K, 5000 K, and 8000 K) and illuminance (1000 lx, 300 lx, and 100 lx) were created. Both the side by side visual matching and spatial brightness scaling experiments are designed to verify the effects of correlated color temperature on spatial brightness perception. The results of the study show that lighting with high correlated color temperature will have stronger spatial brightness perception than lower ones. © 2011 Wiley Periodicals, Inc. Col Res Appl, 2011 相似文献