Two Masks for Halftone

Abstract

In colour masking for continuous tone processes, the number of masks which is generally required can be reduced if the unwanted densities of the dyes are suitably related to each other. In particular, in a process employing dyes which have three unwanted densities (the yellow having no densities to red and green light and the magenta no density to red light) the three masks required can in certain cases be reduced to two. A suggestion that a similar simplification might be achieved in the masking procedure for halftone processes outlined in a previous paper is examined, and it is concluded that if the unwanted densities of the inks obey the condition which allows the reduced number of masks in a continuous tone process, then the same number of masks in a halftone process should give results which differ only little from those obtainable with the more correct full number of masks.