Deriving channel gains from large-area sine-wave contrast sensitivity data.
A wealth of detection data can be accounted for by a spatial-vision model including a finite number of space-variant, spatial-frequency and orientation-selective channels of varying gains coupled with a detection rule involving probability summation over space and among channels. This paper shows that the detection of large-area, foveally fixated sine-wave gratings can be understood as if it occurred merely as a result of the activity of the subset of channels whose orientation matches that of the gratings, and operating under a peak-detection rule. This simplification makes it possible to show the theoretical relationship between the large-area sine-wave contrast sensitivity function, the channel gain function, and the channel modulation-transfer functions. It is also shown that the human visual system must have many more channels than are normally assumed in spatial-vision models, for otherwise the contrast sensitivity function would show significant bumps. An unlimited-channel model with a given mathematical form for the channels' modulation transfer functions is used to derive a mathematical expression for the (foveal) channel gain function from the large-area psychophysical sine-wave contrast sensitivity function.
D015350:Contrast Sensitivity / Q000502:physiology*; D006801:Humans; D008433:Mathematics; D008954:Models, Biological; D013028:Space Perception / Q000502:physiology*