[Chimera-users] RGB->CMYK color conversion

[Greg Couch]

More information in a FAQ-style:

Which CMYK profile should you use?

If you know the printer, use its profile.  The original question was about 
a Textronix Phaser 740.  Tektronix paid to have that printer calibrated 
and the profile is available from 
<http://www.pantone.com/support/support.asp?idArticle=72&>.  It is also 
available from the manufacturer (xerox.com since Xerox bought Tektronix's 
printer business a while ago).

What if a journal requires CMYK and they don't provide a profile?

If you want the colors printed in the journal to match what you submitted, 
you'll need to ask the publisher for a profile.  If you're too shy, you 
can guess.  For instance, many of the Elsevier publishing group's journals 
still require CMYK but the author instructions don't say which CMYK 
profile to use.  Since they are European company and print on glossy 
paper, I'd recommend the "Europe ISO Coated FOGRA27" color profile from 
Adobe.

Where can I get Adobe ICC color profiles?

Adobe provides free ICC color profiles on their download page, 
<http://www.adobe.com/support/downloads/>.  In that set of ICC color 
profiles there are 10 different CMYK profiles designed for different kinds 
of paper and standards (US, European, Japan).  Those profiles are also 
provided in PhotoShop and some other Adobe products.

When else would I want to use color profiles?

If you're going to send your images to an online photo service, say for 
printing a holiday greeting card with a chimera image on it, then you'll 
want to use the printer profile provided by that service.  For example, 
Costco.com provides printer profiles (the profile can make a huge 
difference, especially with wedding pictures).

I'm using a printer color profile but the image changes color?

The printer profile is used in conjuction with your monitor's profile to 
preview what will be printed.  That set of colors is the common subset of 
the colors that the printer and the monitor can reproduce.  It is the 
previewed colors that will match what is printed, not the original colors. 
The colors should be very close to the original colors, but slightly 
darker.

How do I get my monitor's color profile?

Any recent monitor should come with a color profile.  Alternatively, you 
could use the standard sRGB color profile as an approximation.  You also 
should calibrate your monitor to produce a full range of brightness (if 
there is too much light shining on your monitor, this is impossible). 
See <http://www.pawprint.net/designresources/monitorcalibration.php> for 
one possible method.  If you google for "monitor calibration" you'll find 
more than you care for.  Ideal monitor calibration uses a colorimeter to 
measure the color on the screen (but it's impossible to be perfect, e.g., 
LCD monitors are brighter in the middle than on the sides).