Single-pigment optical mechanism for color opponency in a photoreceptor cell

The single-photopigment color opponency of the basal and distal parts of outer segment, which differently contact the cell membrane, has been simulated. If photoproducts content was close to that of rhodopsin after dark adaptation, the relative spectral sensitivity, RS, of the rod was that of protanope. The basal and distal RS kept within orders of magnitude photochemical decay, being equal to each other at the neutral point of protanope, deuteranope, or normal extra-peripheral vision. The RS difference sign could induce the complementary dichromatic blue or yellow if short or long wavelengths prevail in the light. The cone partial RS were equal to each other at the neutral points of tritanope or normal central fovea, breaking the visible spectrum into a green and two red zones. The basic hues varied in saturation over the wide spectral regions and were undistorted for a trichromat in the neutral points and after the rod sensitivity limit. With little photoproducts, the partial RS conform to each other and their difference sign is identical over the retina like from a monochrome image