[argyllcms] Re: Very poor results with 1000+ patch target.

  • From: Michael Gallagher <gallaghermikey@xxxxxxxxx>
  • To: argyllcms@xxxxxxxxxxxxx
  • Date: Tue, 7 Oct 2014 22:18:09 -0600

Success! I made a 524 patch sheet, and using the ruler and slit I was able
to get this on running colprof:

Peak err = 1.633284, avg err = 0.377664, RMS = 0.441556

Here's the IT3 for anyone interested:
https://www.dropbox.com/s/yjdn3a8lxyls2h8/Arches_524_i1.ti3?dl=0

I'm assuming this is pretty good, right? Either way, the resulting test
print was, by far, the best that we've seen. My wife and I are very happy
with it. Thank you all for the help. The next step will be to figure out
the scanner's accuracy, since that does seem to be off slightly.

Kamil and Alan: It turns out the ColorSync app DOES correctly print out
targets (of course, when "Print as color target" is selected). To test this
I cropped a strip of patches from a target, and printed two of them side by
side. One with ColorSync and the other with Adobe CPU. When comparing the
two rows, there is no difference between them at all.

Matthew: we're in northern Utah. The processes you mentioned sound very
interesting, and I would love to see that PDF. My understanding of color
matching is quite limited (my wife is the artist, but I'm a CS student and
I'm comfortable on a command line so figuring out ArgyllCMS became my
thing), but I am interested in seeing how others do manage to do stuff like
this. Do you coat your papers, or use inkjet watercolor paper, or anything
of the sort? One thing I'm noticing is that the thin lines don't seem to be
quite as sharp when printed. It's not that bad though. I'm assuming this is
just because I'm printing on a paper not meant for printing.

Graeme: Thank you very much for your suggestions. A couple questions: is
there much to be gained from optimizing the profile I have? e.g. running
targen -c with my new ICC profile. Also, after running colprof -v, the ICC
file shrinks in size. It went from 1.2 MB to 279 KB. Is that profile still
usable?

Thanks again,

Mike

On Mon, Oct 6, 2014 at 1:11 AM, Kamil Tresnak <kamil.tresnak@xxxxxxxxx>
wrote:

> Hello Michael,
>
> maybe, the problem is in the printed charts, maybe there is a
> difference between printed chart and ColorSync PDF export. Your
> printed chart - seems like OK? Maybe you can find some colors which
> are exactly same (CMYK source valueas) on both charts (maybe full
> c/m/y) and make spot color measuring to ensure that you dont have
> problem with printing output.
>
> Regards,
>
> Kamil Tresnak
>
>
> On Sun, Oct 5, 2014 at 4:01 AM, Michael Gallagher
> <gallaghermikey@xxxxxxxxx> wrote:
> > Hmm... here's something I just noticed. In ColorSync, when I select
> "Print
> > as color target", the colors in the little preview window end up changing
> > drastically. Is this normal? I saved the preview as a PDF on the bottom
> of
> > the Print window to show you guys. Here they are:
> >
> > Original Argyll generated TIF target:
> >
> https://www.dropbox.com/s/kfp78d7oytepynh/1050_Arches%20Original.tif?dl=0
> >
> > ColorSync Target saved as PDF:
> >
> https://www.dropbox.com/s/b6pvvsgniw9misz/Arches%20ColorSync%20Target.pdf?dl=0
> >
> > I'm going to try using Adobe's Color Print Utility to see if the same
> thing
> > happens during the print.
> >
> > On Sat, Oct 4, 2014 at 7:39 PM, Ben Goren <ben@xxxxxxxxxxxxxxxx> wrote:
> >>
> >> On Oct 4, 2014, at 6:23 PM, Michael Gallagher <gallaghermikey@xxxxxxxxx
> >
> >> wrote:
> >>
> >> > Forgot to ask again: After I make this new target, is there any way to
> >> > generate targets/patches from a JPEG to optimize the profile?
> >>
> >> That sort of thing is much more useful for input (camera or scanner)
> >> profiles. In your case, what you'll want to do is use the "basic"
> profile
> >> you're about to create to "pre-condition" the patch generation
> algorithm in
> >> targen; see the "-c" option.
> >>
> >> b&
> >
> >
>
>

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