Three pigments in normal and anomalous color vision*

We show that the color matches of normal and anomalous trichromatic observers, taken together, uniquely determine the spectral sensitivities of the normal red- and green-sensitive pigments for wavelengths longer than about 530 nm. The key assumptions are (i) that a visual match is a match for the pigments; and (ii) that one pigment is common to normal and deutan observers, another to normal and protan observers. Calculated spectral sensitivities for these two pigments agree closely with the luminosity curves of protanopes and deuteranopes. We show also that simple protanomalous and deuteranomalous observers may share a third (anomalous) pigment. The spectral sensitivity calculated for this pigment is reasonably consistent with recent measurements on anomalous vision.