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2006.12.06 04:45 "Re: Grayscale, or is it?", by Edward Lam
> > The standard conversion from RGB to gray, documented in the textbooks, > > is grey level = .33R+.5G+.17B. So a unitary conversion back to RGB is > > fine. > > And of course this equation is acknowledged to be wrong - you can't > combine gamma encoded values like this to give a correct greyscale. Charles Poynton has a nice note explaining this: http://poynton.com/papers/YUV_and_luminance_harmful.html Found from the the wikipedia article, http://en.wikipedia.org/wiki/Luma_%28video%29 -Edward