Discrimination of illumination and reflectance changes on color constancy

Human perception of the color of physical surfaces is practically not affected by changes in illumination. This phenomenon is called color constancy. Based on results of previous psychophysical experiments, it has been established that there are two types of color perception: apparent color and surface color It has also been suggested that unless there is a complete adaptation to the illuminant, color constancy can be achieved only with respect to the surface color, Computational models of color constancy boil down to problems of estimation of reflectance of the observed object based on the magnitude of the sensory response, and duality of color perception has not been adequately addressed in previous studies. This study was undertaken for the purpose of making clear the characteristics of the two types of color perception (apparent color and surface color). The experimental technique used in this study was based on the detection of changes of illuminance and reflectance for the purposes of determination of the effect of the surround stimulus on color perception, rather than on conventional color matching technique. The results of the study indicate that the surround stimulus exhibits an inhibitive influence on the color perception of the center stimulus, and the effect of the size and spatial structure of the surround stimulus is different with respect to the apparent color and the surface color. It was also demonstrated that results of the experiments can be explained by a hypothesis of a hierarchical structure of the vision system combining two different types of color perception. (C) 2000 Scripta Technica.