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  1. #1
    slehning is offline Member
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    Default Newbie to Flexo Color Management

    I have worked in Commercial offset my whole career, and recently made the switch to label Flexo Printing.

    OK so now I know, the Flexo presses can not accept CIP 3, I get it.

    My dilemma is being given the task to finger print the presses. I am trying to go towards the direction that I used for offset, Start out with Linear plates, 1% = 1% 25% =25% 50% = 50% and so on. Then record the data from the print run and calculate the needed dot gain compensation from there. Then applying my curve to new set of plates and verify the new plates with compensation curve.

    I am being lead to believe that may not be the case in Flexo. I've read some documentation that says there is perhaps a bump-curve used to compensate for high lights only. The concerns is with the shadows possibly plugging at the 80% dot with Linear plates, etc.

    Just wanted to get some verification that my Linear methodology is still correct for Flexo.

    Also, while we are at it, can anyone point me to some info as to what spectro devices are supported in the Curve 2 software for calibrating to G7 methodology. Looking at getting this software, but have to come up with a budget to do so.

    Thanks in Advance for the Help

  2. #2
    gordo's Avatar
    gordo is online now Senior Member
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    Quote Originally Posted by slehning View Post
    [snip]
    My dilemma is being given the task to finger print the presses. I am trying to go towards the direction that I used for offset, Start out with Linear plates, 1% = 1% 25% =25% 50% = 50% and so on. Then record the data from the print run and calculate the needed dot gain compensation from there. Then applying my curve to new set of plates and verify the new plates with compensation curve.
    [snip]
    Just a sidebar lest someone takes this as a guide... Your methodology of linearizing the plate for offset was wrong. There was no need to start with linear plates and doing so can compromise the quality of the curves you built.

    Best, Gordo

  3. #3
    slehning is offline Member
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    Where do you start from then uncalibrated?

  4. #4
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    Greg_Firestone is offline Senior Member
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    Quote Originally Posted by slehning View Post
    Where do you start from then uncalibrated?
    Hi Slehning,

    Technically you don't need to linearize your plates and also apply a press curve if you're running CTP. It's double the work. You can just apply a press curve. The output of your plates needs to be repeatable and consistent from plate to plate. The CTP device should be able to achieve this when set at the manufacturers' specs. Your press curve will correct any issues gain issues on press.

    I wouldn't call the plate output uncalibrated. I'd say it's at a repeatable state.

    (Referring to offset processes. I can't speak for flexo)

    Greg
    Premedia Software Inc.

  5. #5
    Lammy's Avatar
    Lammy is offline Senior Member
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    Default

    sorry to continue the side track but, so that would mean you would have to record the results of an plate with no cure to know what the platesetter is producing and this would become your standard for correct exposure of the plates? So when an issue comes up you can go back to this to be sure the plate setter is still exposing correctly?

    Back to the topic at hand, I believe the latest Gracol has a G7 standard specific to flexography.

    Calibrating, Printing, & Proofing by the G7 Method for Flexography

    http://files.idealliance.org/G7/Pres...Supplement.pdf

    New G7 Qualification for Flexo - WhatTheyThink
    Matthew "LAMMY" Lamoureux
    918 Printery - Ad artem artium conservatricem conservandam

  6. #6
    slehning is offline Member
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    Thanks all, I appreciate the Help

  7. #7
    gordo's Avatar
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    Quote Originally Posted by slehning View Post
    Where do you start from then uncalibrated?
    Greg answered it well. Adding to what he said. "Calibration" means being put into a known state. With CtP calibration is done when the engineer sets up the plate exposure and processor to deliver a robust image on the plate. The result is a calibrated platesetter that may, or may not, have a linear response. However since it is calibrated it can output a plate to be run on press, its resulting tone reproduction can be measured, and a tone reproduction compensation curve can be easily calculated.

    Best, gordo

  8. #8
    gordo's Avatar
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    Quote Originally Posted by Lammy View Post
    sorry to continue the side track but, so that would mean you would have to record the results of an plate with no cure to know what the platesetter is producing and this would become your standard for correct exposure of the plates? So when an issue comes up you can go back to this to be sure the plate setter is still exposing correctly?
    Basically yes. Normally you would be measuring your plates - either their natural tone response (calibrated/no curve) or curve applied. You have a target tone value for the plate as well as a tolerance. That is your standard.

    Best, Gordo

  9. #9
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    I see that you have already been pointed you to the IDEAlliance documentation for Flexo.

    Your Curve2 question...
    Curve2 does not take input directly from devices. It will only take data files already generated from other software. Most people measure with an i1iSiS or and i1 Pro. I don't have experience with Techkon products (Densitometers and Spectrophotometers | Techkon USA) but I'm sure that they have software for chart reading with their devices as well.

    With an i1 variant you'll need this:
    ColorPort (free - if you have ProfileMaker then you already have a tool like this)
    Images (p2p25xa chart)
    CHROMiX / HutchColor - Curve2: Pressroom Curves for G7 GreyBalance (curve2)

    Alternatively, there are other solutions other than Curve2 and Xrite devices...
    From Fujilfim
    ColorPath Sync | ColorPath (Taskero Universe) | Consultative Services | Graphic Arts & Printing | Fujifilm USA
    From Heidelberg (particularly useful if you have ImageControl)
    Heidelberg - Prinect Color Toolbox
    There are others out there as well....

  10. #10
    Stephen Marsh is offline Senior Member
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    Back to the OP on flexo and away from litho, slehning, it depends on the flexo imaging and plate technology being used.

    The method that you describe is how one would fingerprint a press for use with the Kodak Flexcel NX system, running a standard narrow or wide web linear test plate printing only cyan. The cyan test form is then measured and compensation curves are then generated for CMYK (generally aiming at a tonal response similar to say ISO coated). A CMYK press run is then performed. The imaging and plate technology used in Flexcel NX does not have the same degree of issues with highlight and shadow tones or lower solid ink density as usually found with standard flexo LAMs plates (yes, I work for a vendor of the Kodak Flexcel NX system).

    With traditional flexo imaging and LAMs plates, one would have to apply a bump curve and be more concerned with a compressed tonal range. Even if you did run an uncompensated test file, you would then see where the highlight and shadow tones drop out and plug in and could then build a highlight bump curve to compensate and set a minimum dot etc.

    There has been a lot of movement in technology in flexo imaging and plate technology in recent years, with many competing systems on the market from old players and new. I would strongly suggest that one engage the various vendors and perform tests on your press, with your anilox, inks, media etc. Let the various vendors put their claims to the test.


    Stephen Marsh
    Last edited by Stephen Marsh; 12-13-2012 at 06:47 PM.


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