[argyllcms] Re: AW: Black generation and black ink limiting

  • From: Vladimir Gajic <vgajic67@xxxxxxxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Thu, 1 Apr 2010 11:10:00 +0200

Hello Fabrizio,

I also did a lot of experiments with FOGRA39L and different
separations/black generations. Basically I like the Argyll-generated
separations more than the ones I get using the original profiles. Even if
some primaries appear a bit more dirty than the originals, my separations
are allways very smooth so that a color correction (even a default one) is
not a problem at all.

About the black generation / TAC: The examples you posted -were they
generated before or after calculating a profile? I have the expirience that
my curves become smoother after generating a profile (using parameters witch
I test with xicclu -v -g -fif -kp......) and than calling xicclu -v -g -fb
-ip <profileName.icc> Depending on the profile quality (medium or high), the
curves may even become more smoothened. My "old" way of testing the
separation quality of a profile is simply in generating a Lab-ramp (from 0 0
0 to 100 0 0) and converting using perceptual ri. This what you see in your
separations responds almost exactly to what you will get running xicclu -v
-g -fb -ip profile.icc Argyll also offers a few excellent images of testing
profile conversions.


2010/4/1 Fabrizio Levati <fabrizio.levati@xxxxxxxxxxxxxx>

>  Hi Vladimir,
> > Maybe it would be good if Fabricio could tell us for which printing
> technique
> > the profile will be prepared for.
> I was trying to create a profile starting from FOGRA39L with the purpose of
> limiting the TAC to 240% or less. This profile is intended to be tested in
> re-separating ads files before printing them on newspapers.
> > If it is for offset/weboffset printing, Than
> > I don't see the reason of limiting the TAC to 220% at the same time while
> > limiting the black down to 92%.
> > Even if you would manage to get smooth curves
> > with that setting, I rather would question the quality of your final
> print.
> > 220% is OK but IMHO the black should not be under 95%.
> No objections at all! I started with TAC 240% and 95% black, saw that
> playing with the total ink limit caused the curves to become rough at the
> edge and get curious...
> Fabrizio

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