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LakeBookBob
05-19-2010, 06:19 PM
David,
1 questions on Ink Optimizer
We have run a demo on Colorflow Ink optimizer against another vendors system.
We saw that the Colorflow system performed more accurate reproductions for PDFs with Transparency then the system tested against. We were also very pleased with the results within our workflow vs. a system outside the workflow
Question:
When a Pdf with Photoshop Raster images is submitted for ink reduction, does all of the file get (GCR/UCR) or only the areas which exceed the TIC max level set by the user?
I know that vector art can be set up not to change but what about Raster art with values not over our desired TIC?

I ask because we did have some overseas jobs with 350+ TIC in heavy area's and some light gray CMY only in other area's, in the same image.
The result after ink Optmization was a file with a very close delta E of less the 1.8 everywhere but the light Gray CMY was reduced and Black introduced.

Normally this would not be an issue on a first printing but matching a printed sample was a challenge with 4colors vs.3 colors.

Eventually we edited the file in Photoshop using GCR which also created a file that controlled High TIC values and left other area's alone.
Thoughts?
:)

david.herder
05-19-2010, 07:05 PM
Hi Bob,
Thanks for the feedback on the product, I'm glad you are having good results!

As you have described, there are two controls in operation here: TAC and Black Strength modification. If you have files coming in that exceed your desired TAC, they will be reduced according to what you have set in your DVL definition. This is applied to all images. Obviously, if you have images below your upper threshold, the TAC value is not increased. With regard to the Black Strength values (UCR/GCR), this is applied to all images. If your intent is merely to control TAC, and preserve CMY builds, then I would advise simply using a constrained DVL that is not Ink Optimizing. However, you may get the result you want with a DVL that has a very minimal black strength value so that a lesser amount of black is introduced on replacement of CMY. Of course, when you do this, your CMY ink savings is reduced.

In a case such as this, the theory is that the CMY replacement for K will be identical colorimetrically. However, there is this fun thing called registration and press drift that we all have to deal with and plays havoc with visual matching of greys. This throws an interesting curveball into ink optimization strategies.

In your case, I would recommend creating an Ink Opt. DVL that has reduced black strength and use that only on jobs where you have numerous CMY greys that must be matched precisely from a previously ran job.

cheers,
dave