[lug] Gimp CMYK

[Michael J. Hammel]

On Tue, 2003-04-08 at 09:29, jd wrote:
> Hello,
>   From looking on the web it appears that GIMP does not support
> CMYK yet. So I was hoping someone could give me some input on
> converting to CMYK using another program (Phototshop). Will
> this make big chages to the picture?

Depends on the colors in the original.  In Photoshop you can check to
see if the colors are "out of gamut", though I don't know exactly how to
do this - I just know it can be done.

> Also, just in general is the GIMP recomened for projects
> that will be printed..such as flyers and brochuers?

If you aren't real picky about the colors (they don't have to match
exact but just be pretty close) then GIMP is fine for this.  I've done
lots of flyers, etc. with GIMP.  I did the covers of both my books and
lots of magazine artwork (the last 4 issues of LinuxFormat have
tutorials I've written on GIMP that include a colorful splash image at
the front - the upcoming issue will feature a new, fairly bizarre image
I did that came out very nice, IMHO).  Just be sure to generate an image
that is at the correct resolution.  An 2x10 image for the front of a
trifold brochure printed at 150DPI would be 300x1500 pixels in size when
you create it.  Be sure to set the DPI for the image before saving as an
uncompressed TIFF image (uncompressed so you can avoid issues with
incompatible compression/decompression software).

CMYK conversion is necessary for mid to high end print processes - note,
for example, that your home printer doesn't need you to convert to
CMYK.  Most conversions from RGB to CMYK can be done by your print shop
and it doesn't usually cost much, if anything.  The printing itself will
generally be the bigger expense (speaking as a consumer of print
services and not as a print shop employee myself).  So, unless you need
absolutely exact matches, you can use GIMP to produce uncompressed RGB
TIFF images and hand them over to your print shop, letting them convert
to CMYK if they need to.

> Are there any RGB to CMYK converters I can run on a image
> that work for Linux? Perl or Python module maybe?..
> couldnt find anything on CPAN.

ImageMagick does this, I think:  http://www.imagemagick.org/
Not sure of any others that do it, though there are probably a few
programs that can.  You might even be able to generate CMYK EPS output
using Ghostscript, CUPS and/or GIMP-Print, but don't quote me on that.
-- 
Michael J. Hammel           |   It is not only what we do, but also what we do 
The Graphics Muse           |       not do, for which we are accountable. 
mjhammel at graphics-muse.org  |                    -- Moliere
http://www.graphics-muse.com