Re: [Gimp-developer] RGB to YMCK conversion
> all colors can be specified with light wavelength measures isn't that true? > can't it be that instead of RGB color you say > light color wavelength instead? Not at all. There are lots of coloursthat are not equivalent to that of visible light of some single wavelength. Just think of purple. The term "colour" as used here means "colour as perceived by a human with normal colour vision" . Without referring to some animal's perception (or technical sensor's), the term "colour" is meaningless, and what actually exists in the physical sense is a spectrum of (visible) light wavelengths. Only so-called spectral colours (which are a very limited subset of the colours we can perceive) correspond to a specific wavelength of visible light. Read up on colour perception. For instance, start with http://en.wikipedia.org/wiki/Color , http://en.wikipedia.org/wiki/Spectral_color , http://en.wikipedia.org/wiki/Color_vision , http://en.wikipedia.org/wiki/CIE_1931_color_space and http://en.wikipedia.org/wiki/Purple . Ideally and simplified, for single largish fields of uniform colour, "idealistic" colour models as RGB or CMYK are as far as I know equivalent. But that is not what usually is meant when talking about "CMYK support" in software like GIMP. CMYK is used to describe colours in images as printed by actual physical processes on paper. In that context there are lots of very arcane and small-scale additional details that affects how the image end up looking. Think of issues as how well different inks can cover each other, how inks spreads onto the paper, what the colour of the actual paper itself is, how much ink can be printed before the paper cannot absorb any more and the ink starts to smear or whatever, etc. I am really no expert in this, but I do know enough that I understand this is not anything trivial;) --tml ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
Re: [Gimp-developer] RGB to YMCK conversion
Jason mclaughlin wrote: > I was thinking > > all colors can be specified with light wavelength measures isn't that true? That's not a bad incoherent rant ;) I can recomend the book 'Understanding Color Management' by Abhay Sharma http://www.amazon.com/Understanding-Color-Management-Abhay-Sharma/dp/1401814476 And the varoius Wikipedia articles on RGB, CMYK, Lab, Color etc etc. BR, Martin ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
[Gimp-developer] RGB to YMCK conversion
I was thinking all colors can be specified with light wavelength measures isn't that true? can't it be that instead of RGB color you say light color wavelength instead? then say the same for YMCK color too? then can't there be where the same wavelength measure means the same color in RGB and YMCK? then you can say every color is evenly inbetween can't you? like for RGB color say wavelength measure, then say wavelength measure is YMCK color... because of how you can say a wavelength measure for RED, GREEN, and BLUE... then say the wavelength measure making for red is RGB red and the wavelength measure of green is RGB green... then from wavelength measure of RED to GREEN is a number that goes evenly from RGB red to green. so BLUE is wavelength measure 475nm and GREEN is wavelength measure 510 so can't you say RGB BLUE is 475 then RGB GREEN is 510 back and forth? then color from BLUE to GREEN is even inbetween like RGB color inbetween? so then can't YMCK colors match a wavelength measure too and say from yellow to magenta is wavelength measure? so then RGB to color wavelength and color wavelength to YMCK? if you say where composing colors are as wavelength measure and just say that between any two colors is between two wavelenth measures? ok right,.. that screws up... because instead of nm of light wavelength you can say many parts of what are together as one light wavelength... so if for 475nm i could say 5 or 6 numbers added together that make for the color at 475nm, then those numbers would have to add up for every other wavelength to say the same color... where shifting the numbers together move between colors at wavelengths the way that they always add together to say a color and can between wavelength measure at same color. so if someone knew math... 475nm is instead 6 numbers maybe... and 510nm is different numbers added together.. then at 475nm you say those numbers added together, and with some kind of rule for how the numbers shift and add together, they stay consistent how they add together to say the color at a wavelength measure. so several numbers added together say color at 475nm, then same colors shifted can follow wavelength equilivent of color if you see how one wavelength is a few numbers added together then another is too, but the numbers that add together shift to mean colors at wavelength measure, like they can shift evenly with wavelength color. so each number is a color part that together means one color. can't that work? doesn't there have to be a rule of numbers added together and shifting that stay even with colors in light wavelength? so the rule of a few numbers added together is color at 475nm and other numbers add together to be color at 510nm, but the numbers shift to be color smoothly between 475nm and 510nm.. like, the rule of how they shift can be found no? then can't the shifting rule work between YMCK colors too given another way to shift... so back and forth between RGB and YMCK is by the numbers that add up? ___ Gimp-developer mailing list Gimp-developer@lists.XCF.Berkeley.EDU https://lists.XCF.Berkeley.EDU/mailman/listinfo/gimp-developer
