Similarity between luminance for mode transition and that of the optimal color for stimuli with different chromaticities

Abstract

Color appearance can be classified into two modes, the surface-color mode and the illuminant-color mode. These modes of color appearance are determined depending on luminance of the stimulus. It has been reported that transition luminance between the two modes varies according to the chromaticity of the stimulus. We hypothesize that the visual system somehow knows the luminance of the optimal color and uses it to determine the transition luminance. The rationale for this hypothesis is that a stimulus with luminance higher than that of the optimal color is physically luminous. To confirm this hypothesis we compared the transition luminance with the optimal color luminance for various color surfaces under D65 illuminant. We found that the transition luminances between the two modes were not perfectly coincident with the luminances of the optimal color. However the transition of luminances varied in the manner of luminance of the optimal color varied. This suggests that the visual system might determine the transition luminance between the two modes using the luminance of the optimal color.