Chrominance (chroma for short) comprises the two components of a television signal that encode color information. It defines the difference between a color and a chosen reference color of the same luminous intensity.

The idea of transmitting a color television signal as luminance and chrominance comes from Georges Valensi, who patented it in 1938. Previous color television systems tried to transmit RGB signals in different ways and were incompatible with monochrome receivers. As applied to analog television signals, two different words are used, luminance and luma, meaning two different things. ... Georges Valensi was a French telecommunications engineer who, in 1938, invented and patented a method of transmitting color images so that they could be received on both color and black & white television sets. ... -1... The RGB color model utilizes the additive model in which red, green, and blue light are combined in various ways to create other colors. ...

In analog television, chrominance is encoded into a video signal using a special "subcarrier" frequency, which, depending on the standard, can be either quadrature-amplitude (NTSC and PAL) or frequency (SECAM) modulated. 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. SECAM uses two different frequencies, 4.250 MHz and 4.40625 MHz above the video carrier. Analog television encodes picture information by varying the voltages and/or frequency of the signal. ... Look up Video in Wiktionary, the free dictionary Video is the technology of capturing, recording, processing, transmitting, and reconstructing moving pictures, typically using celluloid film, electronic signals, or digital media. ... Quadrature amplitude modulation (QAM) is a modulation scheme which conveys data by changing (modulating) the amplitude of two carrier waves. ... NTSC is the analog television system in use in Korea, Japan, United States, Canada and certain other places, mostly in the Americas (see map). ... For other meanings of PAL see PAL (disambiguation). ... Frequency modulation (FM) is a form of modulation which represents information as variations in the instantaneous frequency of a carrier wave. ... SÉCAM (Séquentiel couleur à mémoire, French for sequential colour with memory) is an analog color television system first used in France. ... For other meanings of PAL see PAL (disambiguation). ... NTSC is the analog television system in use in Korea, Japan, United States, Canada and certain other places, mostly in the Americas (see map). ...

The presence of chrominance in a video signal is signalled by a "color burst" signal transmitted on the "front porch," just after horizontal synchronization and before each line of video starts. If the color burst signal were to be made visible on a television screen, it would look like a vertical strip of a very dark olive color. In NTSC and PAL hue is represented by a phase shift in the chrominance signal within each video line relative to the color burst, while saturation is determined by the amplitude of the subcarrier. In SECAM (R-Y) and (B-Y) signals are transmitted alternatively and phase does not matter. Colorburst is a signal used to keep the chrominance subcarrier synchronized in a color television signal. ... In television broadcasting, the front porch is a brief (about 1. ...

Chrominance is represented by the U-V color plane in a PAL and SECAM video signals, and by the I-Q color plane in NTSC. Example of U-V color plane, Y value = 0. ... This article needs to be cleaned up to conform to a higher standard of quality. ...

See also

• Luminance (video)