Re: Out Of Press Gamut
Re: Out Of Press Gamut
- Subject: Re: Out Of Press Gamut
- From: Roger Breton <email@hidden>
- Date: Thu, 22 Dec 2005 23:33:21 -0500
> Flexo printer
> Epson 4000 with Best Rip (V5.0. SP2)
> Profiler Maker 5.04
> Target was ECI 2002 chart
> DTP41 and EyeOne. DTP was used to make the profiles
> Proofing paper is Epson Proofing Paper Semimatte
>
> I am trying to fine tune the system to get a better proof. There are some
> colors in the image proof sheet we printed after
> making the profile from the ECI2002 chart that, even after a curve adjustment
> and 4 edits in ProfileEditor are still not as
> close as I would like them to be.
You mean the press can hit those colors but they are nowhere to be seen in
the proof?
> I have re read the CMYK Lab values on both the chart and images sheet and they
> have a less than 1 Delta difference.
What are "images sheet", Bill? CMYK Lab values on the chart is OK. Do you
mean "sheet" as on the "proof"?
> Additionally the press gains are within the expected tolerance.
Is this flexo on paper or poly, btw? And what kind of tolerances do you
mean?
> Both the ECI target and the images sheet were run through the same prepress
> workflow.
You mean to say that there is no difference between the way the ECI targets
CMYK colors were treated by your workflow, at the time you made films and
plates, and the way the CMYK images are treated by your workflow, to make
films and plates for printing?
> My challenge is that a light red color on the images proof sheet appears to be
> outside the gamut of the press.
Appears? What is the appearance: darker or less saturated, how is it coming
that makes it out of gamut for you?
> I know if all
> the tolerances are met between the chart press run and the images press run
> that this should not happen.
Well, you can say there is more than tolerances at work, here. Color
modeling and prediction are important variables too. And there is nothing
that says that you will get an exact match even if the profile says you
will.
> Colors can not
> match, as I am finding out, but they should as least be within the color
> gamut.
So you say that, to you, this light red color is definitely within the gamut
of your flexo press?
> In an attempt to diagnose this problem I measured the light red color on the
> images sheet using an EyeOne,
(Sorry, it must be a problem of translation but I'm having difficulty with
visualizing "on the images sheet")
> placed it's Lab
> and xyz values in the first line of a measurement file and then plotted that
> point along with the press profile in ColorThink.
> This color floats above the gamut of the press.
So, ColorThink says the color is out of gamut. I think you can trust
ColorThink for its accurate graphing capabilities.
> I realized that using 2 different instruments could throw a wrench in to the
> mix so I measured patches of the ECI press
> chart with the EyeOne and compared those values with the values of the same
> patches as measured by the DTP41 and felt
> that they were close enough as to not affect the color of the light red so
> much as to "throw" it out of the press color space.
OK, so you ruled out the instruments out of the equation. Good.
> Need some help as to how this color can appear to be printed out of the press
> color space if all other specifications are in
> check.
Then you have to check what the press profile is saying about that color.
The construction of the press profle Lab to Device direction is really the
critical part you want to investigate closer here.
> I have tried both abs and rel as rendering intents and while abs helps a
> little, it is not enough.
Looking forward to read your descrition of how that light red color comes
out on press.
> I have also tried a different paper which also helped a little and I have some
> more paper on the way to try.
Paper as in "proofing paper"?
>
> -Bill-
Roger Breton | Laval, Canada | email@hidden
http://pages.infinit.net/graxx
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