Chrominance
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Chrominance (chroma or C for short) is the signal used in
In
Separating
History
The idea of transmitting a color television signal with distinct luma and chrominance components originated with Georges Valensi, who patented the idea in 1938.[1] Valensi's patent application described:
The use of two channels, one transmitting the predominating color (signal T), and the other the mean brilliance (signal t) output from a single television transmitter to be received not only by color television receivers provided with the necessary more expensive equipment, but also by the ordinary type of television receiver which is more numerous and less expensive and which reproduces the pictures in black and white only.
Previous schemes for color television systems, which were incompatible with existing monochrome receivers, transmitted
Television standards
In
In the PAL system, the color subcarrier is 4.43 MHz above the video carrier, while in the NTSC system it is 3.58 MHz above the video carrier. The NTSC and PAL standards are the most commonly used, although there are other video standards that employ different subcarrier frequencies. For example,
The presence of chrominance in a video signal is indicated by a
Chrominance is represented by the
Digital systems
Digital video and digital still photography systems sometimes use a luma/chroma decomposition for improved compression. For example, when an ordinary
See also
References
- ^ French patent 841335, issued Feb. 6, 1939; cited in U.S. Patent 2375966 "System of Television in Colors", issued May 15, 1945.