Colour vision model

A model relating a stimulus to the inputs and discrimination capacity of a visual system. Receiver spectral sensitivity, illumination and background matter; human colour distances are not automatically perceptual distances for another animal.

Variability in a sensory receptor signal that limits discrimination. A difference in average receptor quantum catch does not alone establish a perceptually discriminable difference.

Expected photon absorption by a receptor class. A simple relative model is $Q_i=\int L(\lambda )R(\lambda )S_i(\lambda )d\lambda$, with illumination $L$, object reflectance $R$ and effective spectral sensitivity $S_i$. Absolute catch also requires geometric and temporal factors.