YUV to RGB Conversion

[Valentin Nikin]

Hello!

https://en.wikipedia.org/wiki/YUV#Co...on_to/from_RGB
Can someone explain to me where from Umax and Vmax coefficients? In BT.601 and BT.709 standards nothing about this values.

[Sharc]

You won't find Umax and Vmax in the current ITU-R BT.601-7 document which refers to digital TV. U,V has its roots in analog color TV. Digital systems define Cb,Cr rather than U,V.

You may find these links helpful:
https://software.intel.com/content/w...ml?language=en
The basic equations are
Y'= 0.299*R' + 0.587*G' + 0.114*B'
U'= -0.147*R' - 0.289*G' + 0.436*B' = 0.492*(B'- Y')
V'= 0.615*R' - 0.515*G' - 0.100*B' = 0.877*(R'- Y')
With R'G'B' in the range of [0,1] the maximum value of V' becomes 0.615 (for R'G'B'=[1,0,0]), and the maximum value of U' becomes 0.436 (for R'G'B'=[0,0,1]).

For the various conversion matrices see here:
https://web.archive.org/web/20120403...onversion.html
For analog TV the "YUV - RGB Color Format Conversion" matrix applies.
In the digital realm there is no U,V, but unfortunately it is often used in exchange of Cb, Cr which is not correct.