Neuromorphic Dual-channel Encoding of Luminance and Contrast

There is perceptual and physiological evidence that the retina registers and signals luminance and luminance contrast using dual-channel mechanisms. This process begins in the retina, wherein the luminance of a uniform zone and differentials of luminance in neighboring zones determine the degree of brightness or darkness of the zones. The neurons that process the information can be classified as "bright" or "dark" channels. The present paper provides an overview of these retinal mechanisms along with evidence that they provide brightness judgments that are log-linear across roughly seven orders of magnitude.