Chromatic adaptation by illuminant matrix products: An alternative to sharpened von kries primaries

Abstract

Previous attempts to predict chromatic-adaptation correspondence have led to a sharpening dilemma-i.e., Von Kries primaries are chosen that do not include in the positive octant all the realizable (x,y) chromaticities. This leads to paradoxical adaptation predictions for the colors that have negative Von Kries coordinates. A solution is proposed here that expresses the asymmetric-matching relation of chromatic adaptation as the product of two matrix transformations, given source illuminant 1 and destination illuminant 2: from source tristimulus values via adaptation matrix 1 to the adapted state coordinates, and from the adapted state via the inverse of adaptation matrix 2 to the destination illuminant tristimulus values. To avoid the sharpening instability, the entire spectrum locus must lie within the positive octant of the adapted state tristimulus space.

Color constancy from invariant wavelength ratios: An algorithm to simplify the chromatic adaptation model

“…The model's inherent simplicity entirely avoids the veritable minefield of conventional chromatic adaptation models including such issues as the relative advantages/disadvantages of different chromatic-adaptation primaries and their effect on color gamut, for example the spectral sharpening or purple problem, and of course the considerable and ever-changing math complexities of Von Kries (e.g., CIE-CAT02) or two-matrix chromatic adaptation transforms. [14][15][16][17] In their place, admittedly, the present model introduces the (relatively minor) complexity of equivalent wavelength for nonspectral hues, which diminishes after initial use.…”

Revisiting the Optical Society of America Uniform Color Scales system: past, present and future challenges

“…In summary, the non‐symmetric matrices proposed by Oleari as new chromatic adaptation models 24‐27 did not assume sharpened primaries or consider Von Kries’ hypothesis, which constitutes an original approach deserving future analyses. It must also be added that the perfect colour constancy assumed by Oleari does not exist in humans (see Fairchild, 20 p. 140), and therefore the influence of different degrees of adaptation must be investigated further in results found using Oleari's approach 24 …”

“…Colour constancy is served by the mechanisms of chromatic adaptation and memory colour (see Fairchild,20 p. 27). By assuming perfect colour constancy, the L OSA ,J,G colour space proposed by Oleari on the basis of OSA-UCS system space was also employed to develop new chromatic adaptation transforms, [24][25][26][27] which are the main components of modern colour appearance models. 3,20 Experimental results showed that the chromaticity of the neutral point is close but not equal to that of the illuminant.…”

“…Specifically, he did this for objects under the main CIE illuminants (A, C, FL11, D50) and any of the two CIE standard colorimetric observers, as well as for Planckian radiators and daylight sources at specified colour temperatures. 24 In summary, the non-symmetric matrices proposed by Oleari as new chromatic adaptation models [24][25][26][27] did not assume sharpened primaries or consider Von Kries' hypothesis, which constitutes an original approach deserving future analyses. It must also be added that the perfect colour constancy assumed by Oleari does not exist in humans (see Fairchild, 20 p. 140), and therefore the influence of different degrees of adaptation must be investigated further in results found using Oleari's approach.…”

Introducing Wpt (Waypoint): A color equivalency representation for defining a material adjustment transform

“…Brill and Oleari have also pointed out that using a pair of transformations that map cone space values into and out of a color equivalency representation can be used to define a CAT . As an example, Brill and Oleari introduced the idea of combining an Oleari MAT with the inverse of an Oleari‐based MAT similar to Eq.…”