[scribus] mixing rgb and cmyk

Martin Tlustos martin_tlustos at wycliff.org
Tue Jun 24 21:29:22 CEST 2008

Am Dienstag, 24. Juni 2008 20:02:32 schrieb Craig Ringer:
> Andrew A. Gill wrote:
> > If you intend to print something out, always use CMYK.
> 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.
> --
> Craig Ringer
Thank you for your advice. So, if I would want to convert an image to cmyk, 
what would I use - Cinepaint, Krita, Gimp?

>    Whatever
> > software you are using will have to convert to CMYK anyways,
> > because that is what the separations will have to be, and those
> > are the colors of the inks that the printer/press will use, so
> > starting CMYK can only help.  The advice for work that is
> > displayed on a computer screen is to stick to RGB, since that is
> > what screens use, but there are benefits to having that be CMYK,
> > as well (for me, the addition of the K channel sort of acts as a
> > separate value channel, which can be useful for brightening an
> > image without introducing color shifts--I would love to see
> > RGBW as a proposed standard).
> >
> > There's also the possibility that it will mask some errors that
> > won't be visible until press time.  For example, I went into GIMP
> > and created a red image (255R/0G/0B), imported it into Scribus
> > and created a red box.  Both are similar colors, and you might
> > not notice any discrepancy until you get the plates back from the
> > printer and for some reason, you've got both colors scaled back
> > to a 90% linescreen, causing that nice, clean edge on the font to
> > become ragged.
> >
> > So CMYK for print work.  RGB for screen work.  But above all
> > else, if ot's possible, do not mix.
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