The optical characteristics of colored dye-forming couplers of a type suitable for use in color films, such as Kodacolor or Ansco Color, are described. Destruction of the color of the coupler by the image dye-forming reactions of color development leads to a negative image composed of the color-developed dye and a positive image composed of unused coupler. It is shown that the effect on color reproduction of the overlapping absorptions of the image dyes available for use in color negative films can be eliminated by the use of colored couplers which have the proper spectral-absorption characteristics. The role of the six masks which are found to be required by a number of the theoretical treatments of the problem of exact color reproduction can be filled by colored couplers having the proper spectral-absorption characteristics. The effect of colored couplers on film speed is also discussed.
W. T. HANSON, JR., "Color Correction with Colored Couplers," J. Opt. Soc. Am. 40, 166-169 (1950)