On the Relation of the Tetrachromatic Theory to the Trichromatic Theory

Abstract

The trichromatic and opponent-process theories are two very different conceptions of the color continuum – perhaps. The formal relation between these two theories of human color vision (i.e., the three-color and the four-color theories) may be understood as a mere transformation of variables in color space. A projective transformation of the color plane unifies the two representations. A simple diagram can be constructed to illustrate relations of color for both the Young-Helmholtz trichromatic theory and the Hering opponent-process theory at once. Schrodinger adds some remarks on the likely phylogenetic development of color vision.