RE:Profiles For Flexo
RE:Profiles For Flexo
- Subject: RE:Profiles For Flexo
- From: Marc Levine <email@hidden>
- Date: Thu, 21 Feb 2002 11:33:29 -0500
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Subject 2 Profiles and press gain - please correct where / when needed.
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- I am a flexo printer and have to deal will gains that are different
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that offset. I know profiling software "knows not CMYK, only LAB. But
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since it reads CMYK tint patches to get LAB values and then a proofing
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device then turns those values back to CMYK tints, I will need to talk
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about CMYK tint patches to get my thoughts across. Presently we are not
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using ICC profiles, (I am in the process of buying a profiling package),
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but we do have a compensation curve in our workflow so tints and CMYK
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images on film are "pulled back" for our press gain. This compensation
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allows us to mimic the 20% midtone gain of an offset press with special
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considerations made for the highlight and shadows areas. If I print the
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target from a profiling software package my 50% magenta area (watch out,
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here comes the dots) will gain to, lets say for this discussion, 90%.
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Also for this example lets say that my present compensation curve "pulls
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back" all 50% areas to 30%. We know that through testing a 30% tint on
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film and plates prints on our presses prints 70%. We now have a 50%
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"pulled back" to a 30%; a 30% printing a 70% which give us the 20%
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midtone gain we want on press for a 50% area. It seems to me that if I do
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not adjust the profile target for my press gain I will have areas that I
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want to print 70% actually printing 90% (since 50% prints 90%), the
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profile will take the LAB value for the 90% and replace all 50% areas
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with that value which would make a proof using that profile look much
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darker that I want it to be. If I linearize the press target will the
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profile software now "pull back" the 90% area to 50% and then assign LAB
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values to that 50% area in which case the proof would look too light
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because I actually want 70% values in the 50% area? With my present
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education on profiling I would opt to "pull back" the profile target,
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print it, make a profile and use that profile for my CMYK proof printing
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workflow - right / wrong?
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--__--__--
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Bill,
I have experience working with an array of media types on high-speed,
solvent based inkjet presses that exhibited a wide variety gain issues. What
Before making a profile, I try and configuring a printing device's behavior,
optimizing it for ICC. Device behavior has to do with the way the machine
builds color density - it may be linear to density response T, density
response E, dot area, or a special hybrid. What ever you do, two main issues
are that you achieve good printability and can efficiently recalibrate the
press to the reference state. It's perfectly viable to linearize a press and
then install a dot-gain curve to open the shadows, giving higher target
fidelity when making ICC profiles. In the case of the flexo press, I would
try and process-control the relationship of your plates to your output (if
possible) and implement and correction/calibration curves when making the
plates. This way, you can treat the plates and the output as one. You just
need to make sure that, in the course of configuring you plate processor,
your settings facilitate your workflow, not complicate it. Once you've done
this, you will construct your profiles and implement them somewhere in your
workflow before or during the plate-making process. A capable profiling
utility will then take care of the relationship of the press/plate CMYK
values to the intended color output values. As long as the press maintains
it behavior, you should see consistently good results. Some profiling
packages, such as MonacoPROOF and MonacoPROFILER also provide linearization
capabilities. The way this works is that primary ramps are printed and
measured prior to profile construction. These linearization curves are then
build into the header of the profile and used to adjust the target data.
Once the targets have been adjusted using the curves, printed, and then
measured, the profile's 3D table is built and it is all saved into the
profile. In the future, you can relinearize the profile buy reprinting the
primary ramps using the embedded profile linearization curves. The software
will then update the curves to compensate for any changes to density. The
new profile is then saved with the updated linearization table and the
original 3D table, giving you output that is consistent with your initial
results. Linearization in your profiling package is simply another tool to
help you implement more process control, allowing for greater print
consistency over time.
Hope this help,
Marc
--
Marc Levine
Monaco Systems
Technical Manager
Sales Division
www.monacosys.com
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