Polychromatic Color Removal - Evolution or Revolution?

The history of employing black ink as a substitute for the grey component of a three-color reproduction will be discussed and the development of both UCR and achromatic structure. The criteria necessary to ensure that a color match is obtained between a conventional reproduction and one produced with color removal will be defined, including the need for four colors in a limited range of tone values, together with the various mathematical models which will provide the effects. The technique employed by Crosfield Electronics in developing Polychromatic Color Removal (PCR) will be described together with the advantages of its application.