Chroma, chromatic luminance, and luminous reflectance. Part I: Basic research and illustration of relations

Pridmore, Ralph W.

doi:10.1002/col.20466

Cited by 1 publication

(4 citation statements)

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“…In Ref. 2 it was concluded, inter alia, that Munsell chroma closely resembles log inverted luminance (whether total luminance, chromatic luminance, or achromatic luminance), as shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 91%

“…The dotted line model [Eq. (2)] is preferred, as slightly closer to Munsell chroma, and is shown in more detail at Fig. 3 as the primary model, to be a basis for further improvement.…”

Section: Models Of Chromamentioning

confidence: 97%

“…The broadly inverse relationship of chromaticness to luminance is inferred in color appearance models, 10,11 but the exact relationship is not clear. Hence, the previous 2 and present studies were carried out. In Ref.…”

Section: Introductionmentioning

confidence: 99%

“…1,2 The first redefined the conventional (CIE) 3 locus of optimum purity for nonspectral colors, from the effectively invisible ''purple line'' between the spectrum extremes to the line from 442 to 613 nm (the locus of optimal color stimuli for nonspectral colors); this facilitates accurate investigation and measurement of color and colorimetric functions in the nonspectral area. The second article (Part I of this study) investigated the relations between chroma, colorimetric purity, and various forms of luminance.…”

Section: Introductionmentioning

confidence: 99%

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Chroma, chromatic luminance, and luminous reflectance. Part II: Related models of chroma, colorfulness, and brightness

Pridmore

2008

Color Research & Application

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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 2 0 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 ¼ B:L ratio 60.1, and (2) (chroma/k) x ¼ B:L ratio 60.1. 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.

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Section: Introductionmentioning

confidence: 91%

“…The dotted line model [Eq. (2)] is preferred, as slightly closer to Munsell chroma, and is shown in more detail at Fig. 3 as the primary model, to be a basis for further improvement.…”

Section: Models Of Chromamentioning

confidence: 97%