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I just can't get this color business straight in my head.
A few years ago, I wrote a POV-Ray scene with clear ocean water. I found a
graph of the spectral absorption of water, and did some numerical integration to
shoehorn it into an RGB vector. The image turned out well, but then I realized
that I'd neglected something (I can't remember what) concerning sRGB. But each
subsequent attempt to improve the accuracy of my water made it less
realistic-looking.
Then I turned my attention to the Cornell box. Cornell publishes the spectral
reflectivity curves of its materials, and it occurred to me that there ought to
be a way to map a spectral curve to sRGB. But I couldn't figure out how to make
a double peak at 549.1 and 611.3 nm look the same as a single peak at 570.1 nm.
I managed to find a Web site that attempted, in the author's judgment, the
"best" spectrum that could be displayed on a computer monitor. He started out
by converting CIE coordinates to sRGB. I figured that learning about the CIE
color space might be worthwhile.
I've been seeing this CIE chromacity diagram since I was 13 years old, but I
don't understand it. (I thought I understood it when I was 13, but I can't
remember what it was that I understood. It obviously wasn't the math.)
I went to CIE's Web site. Way out of my league.
I looked up CIE 1931 color space on Wikipedia. I got lost in the section on
color matching functions. I kept staring and staring and staring at what's
written there, and I can't figure out what the heck it's saying.
Is there a gentle introduction to color spaces out there?
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Am 14.07.2011 04:48, schrieb Cousin Ricky:
> I just can't get this color business straight in my head.
>
> A few years ago, I wrote a POV-Ray scene with clear ocean water. I found a
> graph of the spectral absorption of water, and did some numerical integration to
> shoehorn it into an RGB vector. The image turned out well, but then I realized
> that I'd neglected something (I can't remember what) concerning sRGB. But each
> subsequent attempt to improve the accuracy of my water made it less
> realistic-looking.
>
> Then I turned my attention to the Cornell box. Cornell publishes the spectral
> reflectivity curves of its materials, and it occurred to me that there ought to
> be a way to map a spectral curve to sRGB. But I couldn't figure out how to make
> a double peak at 549.1 and 611.3 nm look the same as a single peak at 570.1 nm.
>
> I managed to find a Web site that attempted, in the author's judgment, the
> "best" spectrum that could be displayed on a computer monitor. He started out
> by converting CIE coordinates to sRGB. I figured that learning about the CIE
> color space might be worthwhile.
>
> I've been seeing this CIE chromacity diagram since I was 13 years old, but I
> don't understand it. (I thought I understood it when I was 13, but I can't
> remember what it was that I understood. It obviously wasn't the math.)
>
> I went to CIE's Web site. Way out of my league.
>
> I looked up CIE 1931 color space on Wikipedia. I got lost in the section on
> color matching functions. I kept staring and staring and staring at what's
> written there, and I can't figure out what the heck it's saying.
>
> Is there a gentle introduction to color spaces out there?
>
Are you aware that I've written an include file for POV-Ray called
CIE.inc that does (among many other things) the mapping of spectral data
to sRGB or any other RGB color space for that matter. It is part of
Jaime's lighsysIV at www.ignorancia.org.
And this pdf-file is the best introduction to the CIE color space I've
seen in the 'net.
http://www.fho-emden.de/~hoffmann/ciexyz29082000.pdf
-Ive
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