Image talk:Spectrum441pxWithnm.png
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[edit] Questions
What is LMS and why can't I see yellow? Where'd you get this image? Can you change the gamma to 1.91, that of my Powerbook G4? What are the frequency ranges for various displays, formats, and calibrators? Can you extend the image to 300 nm? lysdexia 03:38, 18 Oct 2004 (UTC)
Has been discussed extensively on Talk:Color blindness - Han-Kwang (talk) 09:48, 22 Nov 2004 (UTC)
- Hasn't answered all of my questions, only two. Are you saying that if true yellow were shown, the highs would go off the edge of the wheelspace? lysdexia 16:23, 22 Nov 2004 (UTC)
I don't understand the second half of your your sentence. I meant that if you wish to represent yellow as bright yellow (RGB=1,1,0.2), then 400 nm with the same intensity would need to be represented be something like RGB=0.2,-0.5,1.5.
You can take Cyp's C program, change the gamma parameter (and probably fiddle a little bit around with the intensity to make sure that all RGB values stay in range). The current gamma parameter is based on an empirical value measured by various Wikipedia authors. The PNG format contains gamma information, so viewing it on a Mac should not make a big difference. 300 nm is too far in the UV to be seen, except that almost everything shows fluorescence.
Han-Kwang (talk) 16:51, 22 Nov 2004 (UTC)
[edit] Gamma
In its current form, the file does not contain gamma information (PNG gAMA chunk). I’d fix it, but I’m not entirely comfortable with the image upload process – I keep thinking I’ll break something. It can be fixed with pngcrush, using the option -g 66666 (where 1/1.5 = 0.66666…). This has the fringe benefit of making the file smaller. -Ahruman 16:01, 11 December 2006 (UTC)
