Uniform-scale chromaticity diagrams: Opponent-chromatic responses as logarithms of the cone-activation ratios

Chromatic-response functions and a uniform-scale chromaticity diagram are derived by assuming that normal trichromatic vision is obtained by combining tritanopic and deuteranopic vision. Two different opponent-chromatic mechanisms can be related to these two dichromatic visions. The chromatic-response functions obtained are the logarithms of proper cone-activation ratios (CAR). Each opponent-chromatic mechanism consists of two parts separated by a properly defined neutral point that depends on the surround chromaticity. The Abney-hue shift, the wavelength discrimination for trichomats, deuteranopes, and tritanopes, and the threshold purity are well reproduced. © 1998 John Wiley & Sons, Inc. Col Res Appl, 23, 27–38, 1998