YCbCr

YCbCr, Y′CbCr, also written as YCBCR or Y′CBCR, is a family of color spaces used as a part of the color image pipeline in digital video and photography systems. Like YPBPR, it is based on RGB primaries; the two are generally equivalent, but YCBCR is intended for digital video, while YPBPR is designed for use in analog systems. Y′ is the luma component, and CB and CR are the blue-difference and red-difference chroma components. Luma Y′ (with prime) is distinguished from luminance Y, meaning that light intensity is nonlinearly encoded based on gamma corrected RGB primaries. Y′CbCr color spaces are defined by a mathematical coordinate transformation from an associated RGB primaries and white point. If the underlying RGB color space is absolute, the Y′CbCr color space is an absolute color space as well; conversely, if the RGB space is ill-defined, so is Y′CbCr. The transformation is defined in equations 32, 33 in ITU-T H.273.