Retinex—a word coined from "retina" and "cortex"—is a color theory developed by E. H. Land and J. J. McCann. Applying retinex theory makes it possible to model the way that light and color are captured by the human brain.
Two theories, namely, "color constancy" and "brightness constancy" (in which it is assumed that color and brightness are perceived by human eye in disregard of the illumination light), form the core of retinex theory. Moreover, in retinex theory, images can be expressed as "the multiplication of the light illuminating an object and the reflectance of that object."
It is applied in techniques for improving the quality of images.
