Luminance and chrominance

The RGB components are usually highly correlated in natural images. Therefore, RGB primaries are rarely used for image transmission that needs more independent components that would result in more efficient color image representation. For transmission, and before image data compression, the RGB components are usually re-calculated to luminance and two chrominance components that at least partially decorrelated.

Luminance

Y = 0.299 R + 0.587 G + 0.114 B

Chrominance components differ slightly in diferent systems.

For digital television Cb, Cr components are defined:

Cb = 0.564(B - Y) = - 0.169R - 0.331G + 0.500B

Cr = 0.713(R - Y) = 0.500R - 0.419G - 0.081B

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