Re: Who Does the Separations
Re: Who Does the Separations
- Subject: Re: Who Does the Separations
- From: Klaus Karcher <email@hidden>
- Date: Thu, 04 Jan 2007 20:45:05 +0100
Hi Karl,
Who would be familiar with all flavours of CMYK (newsprint, gravure,
flexo ...)?
I think colormanagement can supersede to be familiar with a brunch of
CMYK figures for every print condition, but it's still important to know
some of the principles of ink dots on paper, to understand the basics of
the print technology you use (particularly important for flexo, gravure
and screen) and to have the knowledge or experiance of what can go wrong
to make *good* separations.
[...] the separation (or color
transform) into a printing space (be it CMYK or RGB) should always be
done as the last step.
Acknowledged. CMYK is a evil space for editing, retouching or
composing. It's much easier to work with 3 channels (RGB or Lab) and to
"think" in a perceptional colorspace (LCh, HSB). One can mess up a *lot*
in CMYK.
Worse luck one can't see a mixed up black generation on a digital proof
-- it always emulates the "perfect" print, not a *real* one. CMYK
17/12/11/1 and 20%K looks exactly the same on a ISO coated proof, but
ask a printer to match it and he will kill you. Not even 400% ink does
look worse than 250 on a digital proof for newspaper or LWC.
Otherwise you end up converting from one CMYK to
another and a third ..., losing quality along the way in each one of the
conversions.
That's yet another reason why CMYK can be evil.
CYMK values are unsuitable to describe COLOR, CMYK just describes
percentages of ink on paper (or film, or plates), without saying, what
the ink looks like.
With a good printing profile, that matches the printing conditions,
everybody can perform a perfect separation.
No. IMO That's "rocket science" again. Try it with the sunnyside up on
white background with -- let's say ISO Newspaper or ISO uncoated. Try it
with a deep blue undersea photo and -- let's say three profiles of
different vendors based on the same characterization data. Good luck ;-)
That means, the separation
needs to be done, when the printing conditions are known, i.e. at the
printers.
But what if the photographer or client wants to determine the way of
gamut mapping (or at least the hue of delicate shades of blue) and
doesn't know if the printer favors Profilemaker, Heidelberg or
BasiCColor, perceptual or relative, ... ?
Klaus
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