Illuminant changes under different surface collections: examining some principles of color appearance

Abstract

I report the results of a set of experiments designed to study whether the visual system's adjustments to illuminant changes vary with the surface collection in a scene. Simulations of flat matte surfaces rendered under diffuse illumination were presented on a CRT monitor. Under several surface collections subjects set asymmetric color matches between a standard surface and a test surface that were rendered under illuminants with different spectral power distributions. The three subjects' data span 28 different illuminant x surface collection conditions. Five different standard surfaces were used. Two results stand out. First, a change in surface collection did not induce a substantial change in the effect of illuminant changes on the subjects' settings. In this sense the results are consistent with the hypothesis that the visual system's adjustments to illuminant changes do not depend on the surface collection. Second, the illuminant-induced changes in the subjects' settings for a given surface collection were well approximated by a von Kries model, in which the change in the von Kries coefficients is a linear function of the illuminant change. In addition, I tested the hypothesis that the gain of the signal from each cone class is regulated by the photopigment absorptions originating entirely within that cone class. I found some clear deviations from this hypothesis, which indicates interactions among the cone classes. A first-order quantification of these interactions is provided.