The analog luminance and color-difference components of a color image (in digitized form, as Y, Cr, Cb, in JPEG) or video (NTSC and PAL). If you take the typical Red, Green, Blue colorspace (RGB), you can get YUV from:
Y (or Luma)= 30% Red + 59% Green + 11% Blue Analog Luminance
U (or Cb)=R-Y the red signal component minus the luminance
V (or Cr)=B-Y the blue signal component minus the luminance
The large percentage of Green and the small percentage of Blue (along with Green being sent twice) help to explain why chroma-keying for video is done against greenscreens and not bluescreens like film.
YUV was originally developed for backward compatibility with black-and-white television.
Originally, TV stations only transmitted the black and white signal. When color TV was to be deployed, most people still only owned a black-and-white set. It became clear that transmitting an RGB signal separately from a black-and-white signal would be highly impractical. A system was needed in which a TV station could transmit a signal that could be seen as monochrome on the older but still common black-and-white TV sets, but the same signal should be in color on the new color TV sets. YUV encoding allows the signal had to continue to have the black-and-white image, and the color information is added to it transparently.
Many video filters handle video streams in either RGB or YUV colorspace. Some can handle both.
The human eye is less sensitive to colour variations than to intensity variations. YUV allows the encoding of luminance (Y) information at full bandwidth and chrominance (UV) information at reduced bandwidth.
Often called component video, there are different standards for pro video and consumer video. YUV is used on such video types as Beta SP, a very common pro video editing format.
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