The color impression of a video image is determined by the chrominance (C), which contains the values for color saturation and hue. Although the human eye resolves colors much more poorly than it does brightness information, the color component provides improved detail detectability and a real gain in information.
The color component is transmitted in all television and video systems with reduced bandwidth compared to luminance (Y). In video, the chrominance signal consists of two color components, the color difference signals (R-Y) and (B-Y), which are modulated in quadrature modulation with a phase offset of 90°.
These color difference signals are reduced in level and are referred to as the U signal for B-Y and the V signal for R-Y in the PAL television standard. From the color difference signals and the luminance signal (R+G+B), the color components for red (R), green (G) and blue (B) can be calculated.