YCbCr The three components of component video -- with Y for luma and Cb and Cr for different chroma components. International standard CCIR-601-1 specifies 8-bit digital coding for component video with black at luma code 16 and white at luma code 235, along with chroma in 8-bit two's complement form (centered on 128 with a peak at code 224). This coding has a slightly smaller excursion for luma than for chroma; luma has 219 risers compared to 224 for Cb and Cr. The notation CbCr distinguishes this set from PbPr, where the luma and chroma excursions are identical. YCbCr coding is employed by D-1 component digital video equipment. YPbPr The color difference components used when three video components are to be conveyed in three separate channels with identical unity excursions. YPbPr is employed by analog component video equipment such as M-II and BetaCam. Pb and Pr bandwidth is half that of luma. YIQ A color-encoding system similar to YUV. The U and V signals in YUV must be carried with equal bandwidth, albeit less than that of luma. However, the human visual system has less spatial acuity for magenta-green transitions than for red-cyan. Thus, if signals I and Q are formed from a 123 degree rotation of U and V respectively, the Q signal can be more severely filtered than I (to about 600 KHz, compared to about 1.3 MHz) without being perceptible to a viewer at typical TV viewing distance. YIQ is equivalent to YUV with a 33 degree rotation and an axis flip in the UV plane. Because an analog NTSC decoder has no way of knowing whether an encoder was encoding YUV or YIQ, the decoder cannot detect whether the encoder was running at 0 degree or 33 degree phase. Thus, in analog usage the terms YUV and YIQ are often used somewhat interchangeably. YIQ was important in the early days of NTSC, but most broadcasting equipment now encodes equiband U and V. YUV color system A color-encoding scheme for natural pictures in which the luminance and chrominance are separate. The human eye is less sensitive to color variations than to intensity variations, so YUV allows the encoding of luminance (Y) information at full bandwidth and chrominance (UV) information at half bandwidth.