One of the most important problems in photoelectric colorimetry is the duplication, by physical means, of a given set of color-mixture functions. Several methods are outlined in this paper for the numerical derivation of close approximations to given color-mixture functions using the relative spectral-sensitivity function of a photoelectric receiver and the spectral transmittances of glass filters. The filters are placed either in series or side by side between the source and the receiver. Numerical examples illustrate the methods.
W. E. R. DAVIES and G. WYSZECKI, "Physical Approximation of Color-Mixture Functions," J. Opt. Soc. Am. 52, 679-685 (1962)