Importance of individual differences in cone spectral sensitivities and color matching functions and how to correct for them: tutorial.

This tutorial covers human cone spectral sensitivities and their linear transformations, the color matching functions. We focus on the mean or standard functions and the individual differences that occur between observers and how we can correct for those differences. The differences arise mainly because of genetically determined spectral shifts of the L- and M-cone photopigment curves, variability in the optical densities of the lens and macular pigments, and variability in the optical densities of the three photopigments. These can lead to people seeing colors on displays and on printed or dyed material differently even though, according to color standards, they should all appear the same. Such discrepancies have become more apparent and their correction more urgent with the emergence of narrow-band light sources and primaries that expand the color gamut. The discrepancies can be reduced by using better color standards, but to eliminate them completely requires corrections be made for individual differences.