Television Test Pattern

Television Test Pattern

 

a test image used to monitor the parameters that characterize the quality of a television image. Television test patterns are made in the form of a special chart, a color transparency, or a frame of motion-picture film, or they may be inscribed on the aluminum plate of a monoscope. The simplest types contain only one test element, for example, a field of one color, a crosshatched field, or a shaded wedge, and are used to check only one parameter. General-purpose test patterns contain several test elements for checking more than one basic parameter at the same time. For example, with pattern 0249, which has been adopted for television broadcasting in the USSR, it is possible to evaluate nearly all the television image parameters: format, resolution, tonal distortions, scanning linearity, uniformity of background brightness, intensity of multipath images, and quality of interlaced scanning.

Test patterns used to monitor the quality of a color image contain additional test elements to check the fidelity of color reproduction, the color contrast, and the correspondence of the levels of brightness and of the color-difference signals. Test patterns in the form of a chart, transparency, or motion-picture frame are usually used to check the operation of photoelectric transducers, such as those used in television camera tubes and flying-spot scanners. Test patterns obtained from a monoscope or by electrical means—the latter are a train of pulses having a certain wave form—are used to evaluate the operation of television transmitting and receiving equipment, videotape recorders, and communications lines. Television test patterns may also contain conventional symbols and captions that designate the country, city, or department that is transmitting.

REFERENCE

Krivosheev, M. I. Osnovy televizionnykh izmerenii. Moscow, 1964.

N. G. DERIUGIN

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