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color separation[′kəl·ər sep·ə′rā·shən]
in photography, the separation of radiation of complex spectral composition, emitted or reflected by a photographic or cinematographic subject, into several spectral bands corresponding to the spectral sensitivity regions in the primary layers of a multilayer color photographic material. The number of bands is equal to the number of primary layers, usually three.
Color separation is the first stage in the color photographic process; it produces a set of monochromatic images on a multilayer material. In color printing, the images are produced on individual photosensitive layers and are called color-separated negatives. Ideally, the entire spectral region of the light from the subject is separated into bands that border on each other but do not intersect and that correspond exactly to the spectral characteristics of the primary layers. In practice, however, color separation is always carried out by means of selectively absorbing media (dyes in the primary layers of a photographic material and light filters in the form of colored glass or tinted films), and it inevitably proves to be slightly different from the ideal; for example, the transmission bands may intersect, or the spectral characteristics may not coincide exactly. As a result, distortions in color reproduction occur in the final image; moreover, these distortions theoretically cannot be eliminated during subsequent stages in the color photographic process.
REFERENCEArtiushin, L. F. Osnovy vosproizvedeniia tsveta v fotografii, kino i poligrafii. Moscow, 1970.
A. L. KARTUZHANSKII
color separationSeparating a picture by colors in order to make negatives and plates for color printing. The four-color process requires four separations: cyan, magenta, yellow and black (CMYK). See OPI and DCS.
|The separations are printed individually in this picture to show how each of the four inks contributes to the total image. Typically, separations are put on film, and the printing plates are made from the film. (Image courtesy of Intergraph Computer Systems.)|