Reproduction Processes

technological operations used in preparing printing surfaces from illustrative originals.

Photomechanical reproduction processes are most widely used. Negatives and diapositives are obtained, and then the image is reproduced on a plate or some other printing surface. Test prints are then produced.

A distinction is made between the direct and indirect methods of reproducing multicolored images. With direct reproduction the original is photographed in the printshop. The photographing is done simultaneously through a screen and a light filter, which separates the colors. Any defects of color separation are corrected manually, and thus a certain subjectivity in reproducing colors is introduced.

The more complex indirect method of color reproduction makes it possible to photograph the original on location. The conversion of the original, color-separated halftone image to a screened image suitable for copying is done at a later stage. Thus, a photomechanical method of color correction, or masking, may be used to eliminate distortions. Because the technique is time-consuming and expensive, its use is economically justified only for reproducing art work of the greatest complexity, such as paintings.

There also are reproduction processes that involve electronic equipment, such as automated electronic engraving machines. These processes, which omit the steps of photographing and copying, produce color-separated negatives and diapositives or images on a printing surface. Most of these devices function both as color separators and color correctors, ensuring a high quality of reproduction.