Re: PS CMYK Conversions
Re: PS CMYK Conversions
- Subject: Re: PS CMYK Conversions
- From: Terence Wyse <email@hidden>
- Date: Fri, 15 Aug 2008 11:52:04 -0400
Hi Robert,
Comments inserted...
On Aug 15, 2008, at 10:56 AM, Robert Rock wrote:
I've press proofed the targets, matte laminated them, and have
scanned them
(I used a DTP70 automated scanner). I'm now ready to take the data and
create the CMYK profile (using ProfileMaker 5, but also have Monaco
Profiler
at my disposal).
Just so we're clear, I'm assuming that you have two press profiles;
one made from the unlaminated press sheets and a second profile made
from the SAME press sheets, only laminated. I'm going to refer to them
as the UNLAM profile and the LAM profile.
My intended workflow is as follows:
1) Go through all "normal" prepress process. Client making all
necessary
corrections and reproofs until we have a final okay. The matte lam
profile
has not yet come into play.
2) Set that proof aside. Convert our files to the new matte lam
profile and
press proof again. I will assume that this proof will look quite
strange as
the colors will be more saturated and vibrant to account for the matte
lamination that has not yet been applied. This is the press proof,
as odd as
it might look, that the pressman will run too.
One distinction here, before converting, you must *assign* the UNLAM
profile to the image and then convert to the LAM profile.
Also, when you proof the converted LAM image, you must proof it using
the UNLAM profile in your proofing RIP. This will look strange as you
say but this is the correct way to view/proof the image as it will
print on the press prior to lamination. It may seem logical to some to
proof with the LAM profile but this would be incorrect since this
would show the image AS IF the lamination has already been applied
which is, obviously, not how it will run on press.
So...
* Proof w/ UNLAM profile, color-correct the image until it looks
correct and then proof this final (pre-lam) image with the UNLAM
profile. That will be the "reference" proof.
* Convert the UNLAM image by assigning the UNLAM profile and
converting to the LAM profile ("LAM" image).
* Proof the LAM image using the *UNLAM* profile to preview how it will
look on press, prior to lamination and as a guide for the pressman.
* Proof the LAM image again using the LAM profile, if desired, to see
the final results post-lamination. As a "check", you could compare the
LAM image proofed with LAM profile to the original UNLAM reference
proof to what sort of losses there will be in terms of color
saturation, dynamic range, etc. Just make SURE you give the pressman
the LAM image proofed using the UNLAM profile as a guide on press.
(Whew!)
An alternate workflow (maybe a better one?) would be to go through the
whole proofing/color correction cycle using the *LAM* proofing
scenario since that truly represents the final result. Once the color
is approved on the LAM image/proof, simply proof this image using the
UNLAM profile without converting it. You're effectively assigning the
UNLAM profile and making a proof using the UNLAM profile. Think of
this as doing all the initial proofing color-correction *as if* the
lamination was applied and then finally stripping off the lamination
(proof w/ UNLAM profile) and handing that to the pressman as a guide
proof. Now that I think this through a little more clearly, it makes
sense to me to use this workflow.
Sorry for the thinking out-loud but I think it's important to see both
workflows and how they differ from each other, as long as I didn't add
to the confusion!
3) Intended result: The final press sheets when laminated should be an
improvement over our previous results of get dulled and flat colors
after
matte lam.
The results off the press will likely look strange but once laminated,
the press sheet should be reasonably close to the LAM image proofed
through the LAM profile.
So, I'm getting ready to get into this again as it's been a couple
years
since our last profile. I'm not nearly as expert as most of you
here, so
PLEASE speak up if you have any suggestions or advice. Especially
anything
directly applicable to ProfileMaker 5. Any suggested starting points
for GCR
or UCR or Max Black or Max Ink? I ask this only because the Asian
printers
eyes usually glaze over when I try to get this information from them.
As far as total ink and getting the maximum density/dynamic range,
it's not a bad idea to take a total ink chart such as Don Hucheson's
total ink chart...
("TAC_04,tif" which you can find here: http://www.hutchcolor.com/Images_and_targets.html)
...and assigning the LAM profile to it and converting the image to
L*a*b* (or simply set your info palette to read Lab). Now take your
eyedropper tool and find the patch (probably 400%) that has the LOWEST
L* value (low L* = max density). Let's say this value is "8". To find
a reasonable total ink value, you can generally subtract about 2 L*
from the minimum value, assuming it's at 400%, and then go look for
this new value. In this example, if the min L* was 8, the new "target"
L* would be 10. I would restrict myself to finding this value at
either the 100% or 95% K areas. Once you find where L* 10 is (in my
example), you can then calculate what the total ink limit is. That
should be your target total ink limit for your profiles for maximizing
the available dynamic range. Don't forget to use the LAM profile for
this since this represents the final result.
As far as GCR/UCR, K generation, etc., sort of up to you. I would
suggest GCR over UCR of course. For K start, if you're printing with
AM screening not over about 175line/inch, a K start of not under
15-20% should be fine. If you're printing with 20-30 micron FM
screening, you can easily go as low as 5% for the K start. For K
limit, go 95-100% (not under 90% in my opinion unless the total ink
test above tells you something different).
Hope this helps,
Terry Wyse
_____________________________
WyseConsul
Color Management Consulting
G7 Certified Expert
wyseconsul at mac dot com
704.843.0858
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