The principles of spectral color reproduction, as exemplified by the Lippmann method, and of trichromatic color reproduction, as used by presentday systems, are reviewed. Colorimetry is also based on trichromatic principles, and provides the basis for the quantitative evaluation of color reproduction in television, photography, and printing. Being metameric, these reproductions are affected by changes in illuminant and observer. They are also sensitive to changes in their viewing conditions; these changes can be represented by color vision models, one of which is briefly described.