Comprehensive color solutions: CAM16, CAT16, and CAM16‐UCS

Li, Changjun; Li, Zhiqiang; Wang, Zhifeng; Yang, Xu; Luo, Ming Ronnier; Cui, Guihua; Melgosa, Manuel; Brill, Michael H.; Pointer, Michael R.

doi:10.1002/col.22131

Cited by 198 publications

(218 citation statements)

References 56 publications

(179 reference statements)

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“…Therefore, two gamuts with the same CIELAB volume may appear differently. On the other hand, CIECAM02 and CAM16 could be used to predict the differences because these models can calculate perceptual attribute correlates in their brightness and colorfulness spaces that are tied to absolute luminance. However, the validity of the calculation of CGV in the brightness and colorfulness spaces is doubtful in terms of perceptual color uniformity.…”

Section: Discussionmentioning

confidence: 99%

Analysis of color volume of multi‐chromatic displays using gamut rings

Masaoka¹,

Jiang

Fairchild

et al. 2019

J Soc Info Display

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There are claims that multi‐chromatic displays can achieve a wider color gamut by the use of additional highly saturated secondary color channels. However, there are other claims that these displays lose lightness and/or color saturation at brighter levels. These apparently divergent views have led to some controversy in the display industry and at standard setting organizations. This study examines the color gamut volume for a variety of simulated and measured multi‐chromatic (sometimes incorrectly referred to as “multi‐primary”) displays using combinations of white and/or secondary color channels, such as cyan, magenta, and yellow. Furthermore, a two‐dimensional gamut representation, referred to as “gamut rings,” is introduced to illustrate that the addition of nonprimary optical color channels to a trichromatic (RGB) display can result in a significant decrease in the chroma at higher lightness levels. The additional saturated color channels can increase the gamut volume only around their hues at darker levels. The results also confirm the validity of comparing the color light output and white light output for revealing the design trade‐offs between the high‐peak white and the color‐image brightness for multi‐chromatic displays.

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Section: Discussionmentioning

confidence: 99%

Analysis of color volume of multi‐chromatic displays using gamut rings

Masaoka¹,

Jiang

Fairchild

et al. 2019

J Soc Info Display

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“…In this situation, colour‐inconstancy indices (CIIs) must be employed as follows: First, a chromatic adaptation transform (CAT) allows the so‐called ‘corresponding colours’ to be computed under a fixed reference illuminant ; and next, we can use a colour‐difference formula under such a reference illuminant. In this study, corresponding colours were computed using the chromatic adaptation transform named CAT16 , with complete adaptation ( D factor = 1), using as reference illuminants both, D65 and A illuminants. From corresponding colours under the reference illuminant, the CII will be computed using

Δ E_{ab, 10}^{*}

.…”

Section: Methodsmentioning

confidence: 99%

Colour differences in Caucasian and Oriental women's faces illuminated by white light‐emitting diode sources

Melgosa

Richard

Fernández-Maloigne

et al. 2018

Intern J of Cosmetic Sci

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Objective To provide an approach to facial contrast, analysing CIELAB colour differences (ΔEab,10∗) and its components in women's faces from two different ethnic groups, illuminated by modern white light‐emitting diodes (LEDs) or traditional illuminants recommended by the International Commission on Illumination (CIE). Methods We performed spectrophotometric measurements of spectral reflectance factors on forehead and cheek of 87 young healthy women (50 Caucasians and 37 Orientals), plus five commercial red lipsticks. We considered a set of 10 white LED illuminants, representative of technologies currently available on the market, plus eight main illuminants currently recommended by the CIE, representative of conventional incandescent, daylight and fluorescent light sources. Under each of these 18 illuminants, we analysed the magnitude and components of ΔEab,10∗ between Caucasian and Oriental women (considering cheek and forehead), as well as for cheek–forehead and cheek–lipsticks in Caucasian and Oriental women. Colour‐inconstancy indices for cheek, forehead and lipsticks were computed, assuming D65 and A as reference illuminants. Results ΔEab,10∗ between forehead and cheek were quantitatively and qualitatively different in Orientals and Caucasians, but discrepancies with respect to average values for 18 illuminants were small (1.5% and 5.0% for Orientals and Caucasians, respectively). ΔEab,10∗ between Caucasians and Orientals were also quantitatively and qualitatively different both for forehead and cheek, and discrepancies with respect to average values were again small (1.0% and 3.9% for forehead and cheek, respectively). ΔEab,10∗ between lipsticks and cheek were at least two times higher than those between forehead and cheek. Regarding ΔEab,10∗ between lipsticks and cheeks, discrepancies with respect to average values were in the range 1.5–12.3%, although higher values of up to 54.2% were found for a white RGB LED. This white RGB LED provided the highest average colour‐inconstancy indices: 17.1 and 11.5 CIELAB units, under reference illuminants D65 and A, respectively. Conclusion Colour contrasts in women's faces under CIE standard illuminants for outdoor and indoor conditions may be strongly altered using specific white LEDs. More research needs to be performed on the impact of spectral power distribution of light sources with high colour rendering indices on visual colour appearance of cosmetic products.

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“…Second, the variable q in the above equations corresponds to R c , G c , and B c (or R wc , G wc , and B wc ) in CAM16 (see steps 0 and 3, part 1, in appendix A in Ref. ). For the CIECAM02 model, q in the above equations corresponds to R ′, G ′, and B ′ (see equation 7.12 in Ref.…”

Section: Introductionmentioning

confidence: 99%

Further investigation on the modified hyperbolic function in the CAM16 color appearance model

Wang

Gao

Yang

et al. 2019

Color Research & Application

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In the International Commission on Illumination (CIE) color appearance model CIECAM02, a modified hyperbolic function is used to represent luminance adaptation. The same nonlinear function is also used in the new color appearance model CAM16 [Color Res Appl., 2017;42:703‐718]. Although the modified hyperbolic function seems reasonable based on physiological evidence, it has an infinite slope at the origin, which causes instability for both the forward and inverse modes of the CIECAM02/CAM16 models. In this article, various possible extensions to the nonlinear luminance adaptation function in CIECAM02/CAM16 are reviewed and evaluated. Based on these investigations, the Gill extension to the hyperbolic function that is used to represent luminance adaptation [Proceedings of 16th Color and Imaging Conference, pp. 327‐331, 2008], is recommended at both the lower end (q < qL) and the upper end (q > qU), where q is the appropriate Rc, Gc, Bc (or Rwc, Gwc, Bwc) response. In addition, the new recommended function can be readily inverted for use in the appropriate inverse appearance model. From an extensive analysis using available experimental data sets, we also propose that, for the lower and upper limits of the luminance range in the extended model, the values qL = 0.26 and qU = 150 be used, respectively.

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Comprehensive color solutions: CAM16, CAT16, and CAM16‐UCS

Cited by 198 publications

References 56 publications

Analysis of color volume of multi‐chromatic displays using gamut rings

Analysis of color volume of multi‐chromatic displays using gamut rings

Colour differences in Caucasian and Oriental women's faces illuminated by white light‐emitting diode sources

Further investigation on the modified hyperbolic function in the CAM16 color appearance model

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