Assuming that the photoreceptor response of the human visual system is adaptive and non-linear, we can derive mathematical properties that can account for both color discrimination and chromatic adaptation. This could be due to the photoreceptors’ response to illumination, which is non-linear and varies according to the adaptation state. Assuming the Naka-Rushton nonlinear function and an automatic gain control function, we can derive color discrimination and chromatic adaptation data. We extend the discussion to a three layer model of retinal color processing, and show how we could predict corresponding color data.