Re: Out Of Press Gamut (rewrite)
Re: Out Of Press Gamut (rewrite)
- Subject: Re: Out Of Press Gamut (rewrite)
- From: Roberto Michelena <email@hidden>
- Date: Sat, 24 Dec 2005 00:12:38 -0500
Bill,
Is it possible that you don't have a correct flexo linearization? From
what I've known normalizing the dot gain in flexo presses is tricky,
and usually involves multiple iterations at curve building (like
Barco's Intellicurve for example).
It could be that the dot gain in highlights (as your M=7% for example)
is behaving in a way that the profiling software, with a limited
sampling, can not accurately predict.
I understand that IT8/7.4 was created as a superset of ECI2002
precisely to add some patches that flexo people deemed necessary.
Maybe you should use it.
Nevertheless, your 'color out of press gamut' problem seems to run
deeper. Two other factors come to mind:
1) maybe you're printing flexo on plastic? maybe very glossy or pearl?
in that case, a polarization filter (unfortunately not available in
DTP-41, only in Spectrolino) could cut on the effect of gloss.
2) presence of optical brighteners on the substrate (the flexo print
substrate). While building the profile the software would be
compensating for them, but when measuring the sample alone it
wouldn't. Try disconnecting the compensation from the software to see
what difference it makes in the resulting profile.
Oh, I am assuming when you say "I measured this color" (below) you
mean from the press sheet. (since you say this challenge does not
include the Epson). Am I right? make sure you are measuring it in
absolute Lab mode, in case your software allows for different
measuring modes (as for example relative to the substrate).
-- Roberto Michelena
Infinitek
Lima, Peru
> 2 - Press images to press gamut problem. This challenge DOES NOT
> include the Epson, only the press. One of the colors I am having a
> big problem with when comparing press images sheet to proofer images
> sheet is a light red (6% M, 17% Y). I measured this color, plotted it
> in ColorThink and it is in the proofer gamut BUT it is floating above
> the press gamut. If the parameters / tolerances to run the ECI2002
> target used to make the press profile are the same as the ones used
> to run the press images sheet how can this be? Parameters /
> tolerances between two runs were; cmyk inks within .5 delta E, same
> paper, correct densities, correct dot gain. While I could not find
> the exact values (6% m, 17% y) in the ECI2002 target I did find
> colors below these values so I would guess that I am not printing a
> color on the press images sheet that the profile did not have a
> chance to create by reading the press printed ECI2002 target. So with
> my limited education I would guess that any cmyk color mix I
> subsequently print on the press will fall within the press gamut, as
> log as I honor the parameters / tolerances established when the
> ECI2002 target was printed.
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