Re: GCR Problem
Re: GCR Problem
- Subject: Re: GCR Problem
- From: Terence Wyse <email@hidden>
- Date: Mon, 02 Feb 2009 13:54:54 -0500
You're looking for logic that says...
If current K is >= GCR logic results: leave K unchanged.
If current K is < GCR logic results: convert.
Not sure how to do that with CMYK Optimizer or other products but it
does seem "simple" though.
Terry
On Feb 2, 2009, at 1:42 PM, Jon Crook wrote:
Ok, I lowered my K-start to 10% and that did not make a difference
on the
build we are discussing; however it did lessen the amount of black
that is
taken out of the other photographs in this project.
This seems to be over-engineered for what Im trying to do with it. I
am not
using this particular workflow for profile conversions, Im just
using it for
GCR conversions. Is there a better way to do this?
Seems to me that if some kind of software would just go through an
image
pixel by pixel and apply GCR to a certain ∆E off of neutral then
this would
accomplish what I am after.........I think.
I know what I am after but Im not sure of the best way to get there.
On 2/2/09 11:29 AM, "Steve Miller" <email@hidden> wrote:
Jon,
Your original separations have 11% K in them. You moved your K-
start to 15%.
This could be the reason you are still not getting the amount of
black you
want.
Move you K-start to 10% and let us know what happens.
Regards,
Steve
On 2/2/09 11:24 AM, "Jon Crook" <email@hidden> wrote:
I threw colorimetric accuracy out the window and lowered my K-
start to 15%
and switched on CK-MK-YK ink purities and it was still pulling
from the K
sep and adding to the CMY sep. It wasn't as bad but still present.
There has
got to be a way to do these separations reliably.
On 2/2/09 10:51 AM, "Terence Wyse" <email@hidden> wrote:
Hi Jon,
If you're using CMYK Optimizer and the "dynamic" GCR option, the
resulting conversion can be somewhat unpredictable. It's based on a
lot of factors including the actual pixel area in the image.
While not
exactly your issue, the program will tolerate a certain amount of
excessive total ink coverage depending on the actual pixel area
that
it's sampling and how large it is.
In your case, it might be as simple as the where you have the K
start
point set in the GCR setting. If your K start point is, say, 25%,
then
what you're seeing would be expected where it would actually
REMOVE K
and convert back to CMY. Only solution would be to start the K as
early as you can tolerate.
There's another way to prevent this from happening that may be the
best option. In CMYK Optimizer you should have control over the
primary
+K combinations (CK, MK and YK). By checking this option on, it
should
prevent what you saw happen. You can do the same for secondary+K
combinations as well (CMK, CYK, MYK).
Regards,
Terry Wyse
On Feb 2, 2009, at 11:25 AM, Jon Crook wrote:
I need help understanding what is going on behind the scenes in
Alwan CMYK
Optimizer. I have it set to apply a certain level of GCR and works
beautifully most of the time but once in a shile I get an image
that
seems
to separate the exact opposite to the way that I intend.
Here is an example:
Original build is C=0 M=0 Y=27 K=11
New build through Alwan C=11 M=4 Y=36 K=0
Correct me if Im wrong but isnt this conversion the exact opposite
of what
GCR should be? Since there was not any Cyan or Magenta in the
original
build, I would think that there would be no conversion at all. Im
sure Alwan
applies GCR the same way as other ink optimizing programs. Can
anyone tell
me exactly what is going on behind the scenes so I can better
understand
this process.
Thanks,
--
Jonathan Crook
Director of Color Management
Corporate Image
www.corp-image.com
800.247.8194
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Color Management Consulting
G7 Certified Expert
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--
Jonathan Crook
Director of Color Management
Corporate Image
www.corp-image.com
800.247.8194
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G7 Certified Expert
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