Retouching

the correction of drawings, photographs, and other pictorial materials. Retouching consists of filling in areas with pencils or liquid colors, scratching out certain areas, or using chemical treatment (etching the emulsion of a photographic layer). In printing, retouching is used to prepare originals and to correct negatives and slides before preparing printing plates.

A distinction is made between technical retouching, which eliminates accidental defects (such as spots, dots, and scratches), and gradational retouching, which consists of increasing or decreasing the density of certain areas of a halftone. In mapmaking, separation retouching is used: on line contour negatives one of the colors is emphasized by covering the others, that is, linear elements are separated by color. Retouching is usually done by hand and, for large areas, by airbrush.