The Luminance Balance and Color Appearance Mode of Surrounding Colors Affect Color Constancy

Abstract

On color constancy, we previously demonstrated that changing luminance balance of surrounding bright colored surfaces with constant chromaticity affected the illuminant estimation (K. Uchikawa, Y. Kitazawa, D. I. A. MacLeod, K. Fukuda, 2010), however, the surrounding colors exceeding certain brightness seemed ineffective (K. Fukuda, K. Uchikawa, & D. I. A. MacLeod, 2011). The question here is whether this ineffectiveness of bright colors on color constancy is caused by the appearance mode of bright colors, which transits from surface to illuminant. In the experiments, we used the stimulus consisting of a central test stimulus and 60 surrounding stimuli of six colors (bright and dim red, green and blue). The variable was the luminance of the brighter red and blue colors. The observers adjusted the chromaticity of the test stimulus so that it appeared as an achromatic surface, and evaluated the color appearance mode of the surrounding colors with the number of 0 (surface-color mode) to 10 (illuminant-color mode). The correlation between the luminance balance of surrounding colors and the illuminant estimate was compared with the color appearance score of the brighter red and blue surrounding colors. The results showed that the effect of brightest surrounding color on illuminant estimate diminished at the luminance balance where the brightest color appeared as an illuminant. This suggests that the visual system might be able to get rid of illuminants in the surrounding colors and accomplish color constancy using only surfaces.