Chrominance

Chrominance (chroma for short), is the signal used in video systems to convey the color information of the picture, separately from the accompanying luma signal. Chrominance is usually represented as two color-difference components: B'–Y' (blue – luma) and R'–Y' (red – luma). Each of these difference components may have scale factors and offsets applied to them, as specified by the applicable video standard.

In composite video signals, the so-called U and V signals modulate a color carrier signal, and the result is referred to as the chrominance signal; the phase and amplitude of this modulated chrominance signal correspond approximately to the hue and saturation of the color. In digital-video and still-image colorspaces such as Y'CbCr, the luma and chrominance components are digital sample values.