Inference of global spatiochromatic mechanisms from contrast sensitivity functions

A single spatiochromatic signal can describe both chromatic and luminance cosine gratings by varying the spatial phase of that signal. This signal representation permits chromatic and luminance spatial contrast sensitivity functions to be described as linear combinations of two global spatiochromatic mechanisms. If the spatiochromatic mechanisms are assumed to have Gaussian spatial profiles, we obtain one mechanism with broad spatial frequency tuning and one with narrow tuning. We find that the relative spatial shapes and extents of these mechanisms are in agreement with the center-surround organization of receptive fields of single retinal and geniculate cells. Furthermore, the chromatic responses of the derived mechanisms are in accord with the color-opponent nature of spatially antagonistic receptive fields.