Abstract: Process for the production of a photographic mask for tonal correction by dry dot etching wherein the selection of a particular halftone color separation image or overlaying registering combination of halftone color separation images used in a known process of mask production is not determined on the basis of the subjective attribute of color, i.e., hue, those areas to be color corrected, but is determined on the basis of optical density differences in at least one such halftone color separation, i.e., differences in contrast, between each area to be isolated as a substantially transparent area, and at least one particular background area surrounding each area to be isolated. The density differences can be compared between individual isolated areas and associated background areas directly or as the algebraic sums of such differences for a plurality of such areas. The calculation of the density differences and their comparison can be carried out by a computer.