The colour part of a signal, relating to the hue and saturation but not to the brightness or luminance of the signal. Thus pure black, grey and white have no chrominance, but any coloured signal has both chrominance and luminance. Although imaging equipment registers red, blue and green television pictures are handled and transmitted as U and V, or I and Q, or Cr and Cb, or (R-Y) and (B-Y), which all represent the chrominance information of a signal, and the pure luminance (Y).