Hello David,
I make a full-quote so Reinhard can also read it.
* David Deutsch skOre@skOre.de [2008-04-07 17:07:02 +0200]:
Exact color replication is pretty much in one league with voodoo and other forms of black magic. Trust me - you will always get close easily, but exact replication is ludicrous unless you have a really big budget.
We do not have a big budget ;)
To get back to some of the questions raised in your email:
Pantone: This is a proprietary (ring a bell?) color system based on using exact physical colors. So as it was pointed out, most do emulate Pantone with CMYK, but what is normally done is to use the physical pantone bucket of color for the one referenced in the data used for print. http://en.wikipedia.org/wiki/Pantone
RGB->CMYK: What RGB? ProPhoto RGB, Adobe RGB or maybe sRGB? Strange Insider-jokes aside, there is no perfect mapping as they represent different color spaces: http://en.wikipedia.org/wiki/Color_space
GIMP&CMYK: The GIMP only uses an immediate mapping to simulate CMYK to RGB conversion which is of course lossy as demonstrated above.
The bottom line is that I would avoid trying to overachieve on color management. A lot of people just emulate Pantone in CMYK anyways and nobody notices anyhoo. Making an exact match from CMYK to RGB is pointless as they are used in two completely different types of application - one for the three colored computer screen, the other for four colored print.
Ok.
It should be much more helpful to make a small set of reference colors for the programs we know are used. So you would define a set of RGB colors for usage with the GIMP and Inkscape and then maybe use the provided CMYK colors for scribus and alike.
Yes, that would be really helpful. For the Card we already have it:
- SmartCard bright green: 50,0,100,0 (CMYK), or Pantone: 376C - SmartCard dark green & logo: 70,0,100,0 (CMYK), or Pantone: 361C
Who can help to find colors as David suggested? At the moment we need a fast decision for:
- Printing ~5000 leaflets for the Fellowship (like the green on this http://download.fsfeurope.org/tmp/fellowship-customizable-leaflet-blank.pdf) - webcolor (for the green header on http://www.fsfe.org/, the two greens for the webversion of the card http://www.fsfe.org/design/fsfe/images/fsfe_card.jpg) or do you think they are ok?
But to stress this point again: If this is about materials and brochures that will be printed in limited numbers, the time you put into all the color management (not to mention that most of the proprietary color spaces are not supported in most Free Software) is wasted. There are good and reasonably priced online-printing services (like flyeralarm.de for Germany) who can handle even RGB pdfs very well and the difference in color is negligible. Unless of course you suddenly feel we are Deutsche Telekom and WE NEED EXACTLY THIS TONE OF PINK!
Thank you very much for your explanation. Also thanks to Markus for phoning me on this issue.
Best wishes, Matthias