Episode 195: Whose RGB?

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Colo(u)r ist the topic this time. You are in for a ride from the electromagnetic spectrum to the biology of color vision and the infamous Mantis Shrimp. (Link to the fabulous Oatmeal!)

Grassmann’s Law gives a clue how to create a color sensation in the brain by mixing up some wavelengths out of the spectrum. The CIE finally defines what is visible for a “Standard Observer” and Microsoft & HP (sRGB) and Adobe (Adobe RGB) build their color spaces on that foundation.

Elle Stone, Bruce Lindbloom and Cambridge in Colour help along the way, passing a Black Body emitting radiation according to Planck’s Law at 6500K just to give us a White Point.

Then I organize a shootout between sRGB and Adobe RGB – and I’ll stick to sRGB for the forseeable future.

Finally I cover the question of Intent while converting between different color spaces – Perceptual or Relative Colorimetric?


Elle’s fine writeup about All the Colors.

The Color Space Viewer (at the bottom of the page)

Pascal’s tutorials about color management on Linux – really hands on:



00:00:00 Intro
00:00:15 Submit to GIMP Magazine
00:00:50 Light as part of the electromagnetic spectrum
00:01:43 Biology of color vision
00:06:14 World Champion of Color Vision: The Mantis Shrimp!
00:06:40 Grassmann’s Law – mixing colors from spectral primes
00:07:22 CIE 1931 Color Space – the standard observer
00:09:00 Elle Stone’s blog – a lot about color!
00:09:50 sRGB
00:11:40 D65 – the White Point for sRGB
00:11:56 Black Body Radiation and White Points
00:13:44 Bruce Lindbloom has a Color Space viewer
00:14:30 Adobe RGB (1998)
00:15:50 Why not ProPhoto RGB?
00:16:20 Preparing some test shots in the lab
00:16:59 Comparing sRGB and Adobe RGB camera setting
00:18:42 Conclusion – stick to sRGB
00:19:34 Converting between color spaces
00:20:06 Intent: relative colorimetric or perceptual?
00:21:14 Consequences
00:23:10 Winding down
00:24:09 EOF

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