Spatial Contrast: A Vintage Retinal Model of Color Vision Produces the Center-Surround Opponent Color Phenomena; The Model Was Previously Shown To Produce Mutually Exclusive Opponent Colors by a Different Mechanism
The on-off phenomena of opponent colors in center-surround may be the best-known facts of retinal processing of information. Apparently, however, no explicit model has been proposed that shows how neurons can be connected to produce the center-surround phenomena. Here it is shown that a previous simple model of color vision can produce these phenomena, including the detection of edge orientation and motion famously discovered by Hubel and Wiesel. The model was previously shown to produce major phenomena central to color vision, including mutually exclusive opponent colors. Although the opponencies of mutually exclusive colors and center-surround involve the same color pairs, red-green and blue-yellow, the model produces them by two different mechanisms. Perceptions of two colors are mutually exclusive because only one cone type can have the most, or least, absorption of photons. Two colors have the on-off opponency of center-surround because they have the same network designs up to the ganglion cells, with the inputs reversed there. On-off opponencies with different colors are possible, but natural selection evidently did not choose them.