The YUV standard

The YUV standard (also called CCIR 601), known before as YCrCb (Y Cr Cb), is a colour representation model dedicated to analogue video.

It is based on a video transmission mode with separate components using three different cables to carry information regarding luminance (luminosity) and the two chrominance (colour) components. . It is the format used in the PAL (Phase Alternation Line) and SECAM (Séquentiel Couleur avec Mémoire) standards.

The Y parameter represents the luminance (i.e. information in black and white), while U and V make it possible to represent the chrominance (i.e. information regarding the colour). This model was developed in order to allow colour information to be transmitted to colour television sets, while making sure that the existing black and white television sets continue to display an image in tones of grey.

The following are the relationships between Y and R, between G and B, between U, R and luminance, and finally, between V, B and luminance:

• Y = 0.299R + 0.587 G + 0.114 B
• U = -0.147R - 0.289 G + 0.436B = 0.492(B - Y)
• V = 0.615R -0.515G -0.100B = 0.877(R-Y)

Thus, U is sometimes written as Cr and V is sometimes written as Cb, hence the notation YCrCb.

Cabling

A YUV connection is thus usually based on the use of three RCA cables, one green, one blue and one red:

YUV connection makes it possible to offer an optimal video quality by simultaneously sending the 576 rows of the image, without interlacing (all at once).

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