Originally Posted by dr1394
Be aware that the luma coefficients in rec.601 are not based on the SMPTE-C primaries. They are actually based on the NTSC 1953 primaries and white point.
yes, that's clear in the posts linked above
he needs to let us know what is known..
1 = Kr + Kg + Kb (709: Kr = 1 - (.7152 + .0722) - 601: Kr = 1 - (0.5864 + 0.1146))
The coefficients in the luma equation are based upon the sensitivity of human vision to each of the RGB primaries standardized for coding
i.e. if he has xyY, he needs to convert to XYZ first (Y=1 of course)
if he is asking about the % of R G B in regards to the last quote above, I look forward to his dissertation posted publicly.