Equations for chromatic discrimination models.

Equations are derived to fit the cone sensitivity values of Smith and Pokorny, which are based mainly upon Judd's modified color matching functions and the spectral sensitivities of normal and dichromatic observers. The equations, which fit Smith and Pokorny's values to within 1 to 3%, are smooth and differentiable. Derivatives of cone sensitivities for an equal luminance spectrum, which are of particular importance for models of chromatic discrimination, have been calculated and are shown graphically.