The effect of the variance of surrounding colors on color constancy investigated by achromatic settings

Abstract

In order to achieve color constancy, the visual system needs to estimate the illuminant by referring to the chromatic distribution information in scenes where direct cues to the illuminant were absent. In this study, color constancy was investigated by an achromatic setting with short illuminant durations in five kinds of scenes with different numbers of colors and colored patches. Three of these scenes contained 8, 24, and 96 patches with different colors, and two other scenes contained 96 patches with 8 and 24 colors, respectively. All five scenes had identical space-averaged means, but different variances. The results showed that the color constancy index decreased as the variance of scene colors increased. This indicates that the effect of the number of colors and patches on color constancy was dependent on the scene variance they produced: a greater number of colors and patches tended to generate higher variance, which in turn led to lower color constancy indices. The results suggest that color constancy under brief exposure to multicolor scenes cannot be fully explained by models based on adaptation to the illuminant or mean chromaticity of the scene. Instead, the distribution of colors around the mean also plays an essential role.