2006.12.05 15:52 "[Tiff] Grayscale, or is it?", by Joris Van Damme
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2006.12.05 17:18 "Re: [Tiff] Grayscale, or is it?", by Bob Friesenhahn
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2006.12.05 17:34 "Re: [Tiff] Grayscale, or is it?", by Joris Van Damme
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2006.12.05 17:45 "Re: [Tiff] Grayscale, or is it?", by Bob Friesenhahn
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2006.12.05 18:44 "Re: [Tiff] Grayscale, or is it?", by Joris Van Damme
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2006.12.05 22:10 "Re: [Tiff] Grayscale, or is it?", by Frank Warmerdam
- 2006.12.05 20:37 "Re: [Tiff] Grayscale, or is it?", by Joris Van Damme
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2006.12.05 22:10 "Re: [Tiff] Grayscale, or is it?", by Frank Warmerdam
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2006.12.05 18:44 "Re: [Tiff] Grayscale, or is it?", by Joris Van Damme
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2006.12.05 17:45 "Re: [Tiff] Grayscale, or is it?", by Bob Friesenhahn
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2006.12.05 17:34 "Re: [Tiff] Grayscale, or is it?", by Joris Van Damme
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2006.12.05 22:56 "[Tiff] Re: Tiff Digest, Vol 31, Issue 3", by Glenn Widener
- 2006.12.05 23:26 "Re: [Tiff] Re: Tiff Digest, Vol 31, Issue 3", by Toby Thain
- 2006.12.06 01:58 "Re: [Tiff] Re: Tiff Digest, Vol 31, Issue 3", by Graeme Gill
- 2006.12.06 20:56 "[Tiff] Re: Grayscale, or is it?", by Joris Van Damme
- 2006.12.06 21:57 "Re: [Tiff] Grayscale, or is it?", by Graeme Gill
2006.12.06 04:45 "Re: [Tiff] Re: Tiff Digest, Vol 31, Issue 3", 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