[scribus] mixing rgb and cmyk

[Tino Schwarze]

On Tue, Jun 24, 2008 at 09:29:22PM +0200, Martin Tlustos wrote:

> > This is not necessarily always the best choice:
> >
> > - Many home printers expect RGB input and will do a very poor job when
> >    fed pre-converted CMYK data. You're better off using an RGB colour
> >    profile to transform colours for these printers, then let their
> >    drivers do the CMYK, CcMmYK, etc translation. This is especially
> >    important for "photo printers" and other six-or-more colour printers,
> >    as most CMYK spaces cannot represent their full gamut, where a
> >    wide-gamut RGB space like Adobe RGB is well suited to it.
> >
> > - Modern print shops may accept PDF/X-3 with ICC-tagged RGB data. This
> >    lets you send your data to the print shop in their original colour
> >    spaces and lets their RIP do the conversion with its often superior
> >    knowledge of the performance of the press. Unfortunately, many
> >    print shops will just look at you funny and say "why do you want to
> >    send RGB?" because they just don't get ICC colour workflows, but
> >    a few are starting to get it. It doesn't help that ICC workflows are
> >    hard to get right and somewhat easy to misunderstand.
> >
> > For most print shops, though, I agree that sticking to pre-converted
> > CMYK is currently the way to go.

> Thank you for your advice. So, if I would want to convert an image to cmyk, 
> what would I use - Cinepaint, Krita, Gimp?

Up to now I used the following script to convert TIFF files:

-----------
#!/bin/bash
#

[ -e "$1" ] || exit 1

[ "$1" != "${1/.tif/}" ] || exit 1

filename="$1"
shift

tifficc -i /usr/share/color/icc/sRGB\ Color\ Space\ Profile.icm -o \
  /usr/share/color/icc/ISOcoated_v2_eci.icc -c2 -e -b -t1 $* \
  "$filename" "${filename/.tif/-ISOcoated.tif}"
-----------

But if you want to look at the colors, simply load it into Cinepaint (it
should do the conversion correctly, too) and check there. GIMP does not
support real CMYK yet, it always needs to convert to RGB (there might be
a way to save as CMYK, though, I don't know, I'd rather trust command
line then).

HTH,

Tino.

-- 
"What we nourish flourishes." - "Was wir nähren erblüht."

www.craniosacralzentrum.de
www.forteego.de