Spatial vision based upon color differences

摘要

To understand the role of color in spatial vision, it is necessary to examine both the extent to which spatial discriminations can be based solely upon color differences and the interaction between color and luminance variations when they are simultaneously present. The well-known differences in the spatial and temporal contrast sensitivity functions for color and luminance and the apparently impoverished input from the color mechanisms to certain higher functions obscure the fact that spatial discriminations based solely upon color differences are quite good. For example, spatial frequency discriminations between high-contrast patterns at isoluminance are only slightly poorer than for comparable luminance patterns, averaging about 5% to 6% of the base frequency. Similarly, orientation differences of about 1 deg between isoluminant patterns can be reliably discriminated at high contrasts, even for stimuli that lie along a tritanopic confusion axis. Similar comparisons from several tasks are reviewed, as are tasks involving color-luminance interactions. These provide information about the target behavior that must ultimately be explained if the physiological basis of color vision is to be understood.