# Colors Not Rendering Correctly

After invoking the 'color' package with the command

\usepackage[pdftex]{color}

I defined a new color using CMYK values. More specifically, I set

\definecolor{mybluegray}{cmyk}{.33,.11,.01,0}

However, the color rendered in the document is not the same with color rendered in, say, Adobe Photoshop. To be more precise, I opened the PDF file in Photoshop and checked the CMYK values there, and Photoshop says the color in my document has CMYK values {.25,.08,.04,0}. Can anyone give me some clue on what's going on?

(By the way, I compiled my document on both Mac and Linux machines, and they produce the same color.)

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What CMYK values do you get from the different approaches? –  Joseph Wright Oct 5 '10 at 5:45
A full minimal example would also be good here, I think –  Joseph Wright Oct 5 '10 at 7:23
would `xcolor` work any better? –  Juan A. Navarro Oct 5 '10 at 11:30
Is the issue on a page with transparent objects? If yes, try adding \pdfpageattr {/Group << /S /Transparency /I true /CS /DeviceRGB>>} –  Martin Heller Oct 5 '10 at 18:15
I’d guess that `color` and Photoshop use different color profiles. –  Caramdir Oct 5 '10 at 23:31

This is not a perfect answer, but I did find a work around to my problem. Instead of defining the color using CMYK values, I tried defining it using RGB values:

\definecolor{mybluegray}{rgb}{.58,.67,.81}

The original definition has RGB values (149,172,207) in terms of 0-255 scale. The rendered color is the same as I wanted; I opened the document with Photoshop, and the Photoshop says that the rendered color has RGB values exactly (149,172,207).

So my conclusion is that the 'color' package is not perfect in rendering colors using CMYK values.

Further experiment, however, shows that not all RGB definitions work well. It seems that the definitions using the RGB values for the so called web-colors work best.

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Slightly tangential: instead of `{rgb}{.582,.672,.809}` you can pass the arguments `{RGB}{149,172,207}` instead. Also note that the argument for the `RGB` model runs from 0 to 255, not 1 to 256. –  Willie Wong Oct 5 '10 at 23:28
I see, so by using capital letters, I don't have to convert them into fractions. (I changed the RGB scales in my posting above by the way.) –  user1000 Oct 7 '10 at 1:57