AbstractAn improved quantitative description of the equidistant color and lightness spacing of the Munsell and OSA‐UCS Systems is presented. The basic idea is to apply physiologically acceptable hyperbolic response functions to relate light absorption in and the excitation of the three cone types with visual response. A similar nonlinear equation describes the relationship between the luminance factor Y and a lightness magnitude. Subsequent linear combinations of the nonlinear functions describe opponent‐color transformations. The resulting formulation, called the SVF formula, is superior to the best available empirical formulae, such as CIELAB and CIELUV, in describing the Munsell color space, and it performs even better than the OSA L g j formula on the OSA‐UCS