Color correction by masking for a four-color printing process

Claim 1

In the conventional four-color printing process comprising the steps of preparing a premask, magenta, cyan, yellow and black separation negatives, an undercolor removal mask or masks, and magenta, cyan, yellow and black halftones, the improved method of color correction and undercolor removal, which comprises the steps of: creating a shadow mask by exposing a masking film through the black separation negative, and then developing the image thus created; creating a magenta undercolor removal mask by separately and sequentially exposing a masking film by a first exposure through a first superimposed combination of the cyan separation negative, the yellow separation negative and said shadow mask, and by a second exposure through the black separation, and then developing the image thus created; creating a yellow undercolor removal mask by separately and sequentially exposing a masking film by a first exposure through a first superimposed combination of the magenta separation, either the cyan separation or the premask, and said shadow mask, and by a second exposure through the black separation, and then developing the image thus created; and finally creating the magenta halftone by exposing a film through a superimposed combination of the magenta separation and said magenta undercolor removal mask and a screen, and creating the yellow halftone by exposing a film through a superimposed combination of the yellow separation and said yellow undercolor removal mask and a screen, and developing the images thus created.