On the relationship between the spatial channels for luminance and disparity processing

To determine the relationship between the spatial channels for luminance and shape-from-stereo-disparity processing we measured disparity modulation sensitivity as a function of disparity spatial frequency for sinusoidal modulations of a field of Gabor micropatterns of differing luminance spatial frequency. We first examine the effects of contrast, spatial bandwidth and element density and show that it is only the last of these which is critical for the shape of the disparity modulation threshold function. We show that the shape of this function depends on the luminance spatial frequency of the surface that is modulated in depth. Specifically, low corrugation frequencies enjoy a greater scale support from the early luminance spatial filters than do high corrugation frequencies. The results are consistent with higher spatial frequency disparity channels receiving a greater input from higher spatial frequency luminance channels.