Color Balance for Television

The visual phenomenon of color adaptation must be mimicked by any successful process of color photography or color television. This means that a light gray object should be reproduced so as to appear light gray, regardless of variations of the illumination in the original scene, within a wide range of qualities. In color photography, films of two different classes are commonly provided, one for daylight and the other for incandescent tungsten light. In the present standard system of color television, the color subcarrier should have zero amplitude for a light gray object, regardless of the chromaticity of the illumination, whether daylight or incandescent tungsten light or arc light. Adjustment of receivers to correspond to the adaptation of the viewer is equally important. Although most receivers will be used in living rooms lighted by incandescent tungsten lamps, receivers are sometimes used in subdued daylight. This fact creates a dilemma, which is familiar to the designers of illuminators for color transparencies. A satisfactory compromise has been found: a color temperature of 4,000 degrees Kelvin.