The colour printing industry is based on the use of magenta, cyan and yellow printing inks but these are invariably augmented by a black ink because the best black which can be achieved using the primaries is not intense enough nor is the definition good enough. The effects of unwanted absorption in the case of the magenta and cyan inks are not usually serious enough to warrant a different approach, but when they are then as many as seven separate coloured inks plus black will be used.

The situation is entirely different in colour photography. Here all the best systems for producing both transparencies and prints use very sophisticated techniques to eliminate the effects of the unwanted absorption.