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Linerize or not to Linerize plates... that is the question

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  • #16
    In my view, which is that the optimum method of dealing with the imaging of a plate for reproducing an image on press would not deal with dot gain compensation. Mapping the print output relative to the screen values input would encompass all the information of dot gain. In that condition, I would say that a linear plate is the ideal. Linearity would then be a process control metric for plate imaging.

    But since we don't have such a method, it seems it does not matter as long as the condition of the plate can be repeatable.

    Just my 2 cents.

    Comment


    • #17
      Originally posted by gordo View Post

      You’re right - not a good reason. In my experience, when I’ve seen done what you’re doing, it indicates that there are issues in the print manufacturing process that someone has decided not to deal with and instead apply a band-aid solution that seems easier. They might be too far away from the business of the company to see the loss in profits, efficiency, and effectiveness of their “solution”. Or they’re just ignorant.
      It is not a good reason to recommend it to others as a production proess they should adopt. It is not normal or best practices.
      Yeah well that is a whole other can of worms.
      Joe
      OS: Mac OS X 10.10.2 - RIP: Prinergy Connect 6.1 - CTP: Luscher XPose! 160 (2)

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      • #18
        Originally posted by Joe View Post

        Yeah well that is a whole other can of worms.
        ROTFL ! You should know that you’re not the only one dealing with cans of worms.

        Comment


        • #19
          Well aware.

          Also I was not recommending the way it is done here to anyone.
          Joe
          OS: Mac OS X 10.10.2 - RIP: Prinergy Connect 6.1 - CTP: Luscher XPose! 160 (2)

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          • #20
            I know two cases when separate plate and press curves are better:

            1. There is web offset company here with three CtP and 6 printing machines. It would take 18 curves to do it without linearization (1 curve per CtP per printing machine) and only 9 curves (1 per CtP = 3 curves; 1 per printing machine = 6 curves - these curves are same on all CtP drives).

            2. One CtP working for real many printing machines like in a case where printing house does not have prepress so they use CtP studio or similar solution. In this case printing house supplies changes to press curves whenever they need to and CtP company needs plate linearization to make proper plates. In this case, it could actually run without linearization but it is more practical to have two independent curves: plate curve can be adjusted as needed without impact on press curve. The case I know is about 26 low volume printing houses rely on one CtP studio.

            In vast majority of cases, a single CtP is used for low number of printing machines, 1 curve is easier way to go.

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            • #21
              I think that in some unique situations I agree. Which is why in my original post I said:

              "in the vast majority of cases a curve to linearize the plate before applying a second, dot gain compensation curve, is redundant and adds complexity without benefit. That being said, in a few cases, typically multi- site operations, a two curve workflow can be appropriate."

              My argument being that the shop needs to think it through and not just go the linearization first based on just assuming that's what is correct.

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              • #22
                With processless plates becoming more and more prevalent a two curve solution with a plate curve and a press curve is difficult if not impossible to implement in any meaningful way. In this case I would say that if the optical output of the CTP is within tolerance I would rely on the CTP to give me linear plates.

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                • #23
                  Gentlemen of the Pre- Press Brigade,


                  "Raison d'etre" ...... is to produce - Production Compliant Imaged Lithographic Printing Plates.

                  Instead of talking endlessly among yourselves !!!



                  Regards, Alois

                  Comment


                  • #24
                    Thanks guys for all your thoughtful opinions. I feared this question might create a divided house, and... after reading all your suggestions and questioning other sources I have landed on the opinion of conducting my next G7 certifications without a linear curve.
                    Two points that convinced me that this might be the best solution are:
                    1) In a AM screening environment, the image setter outputs plates somewhat close to Linear(50% images around a 47%), but... in a FM environment, the 50% dot images as a 43%. If going with a Linear curve first, I would have to bring up the dot's considerably (7%)... then remove them again for the press compensation curve, thus... creating a even steeper curve than I feel necessary. Such a steep curve might be more difficult to control and create extra complications while on press.
                    2) If I use my raw plate readings as a baseline, and apply only 1 curve on top of it (press compensa tion curve) then... if the laser weakens or plate lots emulation changes considerably, I can easily apply an additional curve to adjust the baseline back to my benchmark (hopefully the platesetter is more stable than that, and this won't happen). Using this logic... this backup plan would even satisfy the concern about the platesetters stability.
                    I hope this action works for me and that everyone else gained some additional information from this feed.

                    Thanks!

                    Comment


                    • #25
                      Hello Jbarries,


                      Enlightenment ! The Coating on Litho Plates are composed of "Thermosetting Photopolymers " these form the Image areas of the plates when exposed to lasers used on CtP Imagesetters.


                      They are NOT emulsions. !


                      Regards, Alois

                      Comment


                      • #26
                        Originally posted by Jbarrie5 View Post
                        Thanks guys for all your thoughtful opinions. I feared this question might create a divided house, and... after reading all your suggestions and questioning other sources I have landed on the opinion of conducting my next G7 certifications without a linear curve.
                        Two points that convinced me that this might be the best solution are:
                        1) In a AM screening environment, the image setter outputs plates somewhat close to Linear(50% images around a 47%), but... in a FM environment, the 50% dot images as a 43%. If going with a Linear curve first, I would have to bring up the dot's considerably (7%)... then remove them again for the press compensation curve, thus... creating a even steeper curve than I feel necessary. Such a steep curve might be more difficult to control and create extra complications while on press.
                        2) If I use my raw plate readings as a baseline, and apply only 1 curve on top of it (press compensa tion curve) then... if the laser weakens or plate lots emulation changes considerably, I can easily apply an additional curve to adjust the baseline back to my benchmark (hopefully the platesetter is more stable than that, and this won't happen). Using this logic... this backup plan would even satisfy the concern about the platesetters stability.
                        I hope this action works for me and that everyone else gained some additional information from this feed.

                        Thanks!
                        Two things:

                        1 A two curve workflow can introduce tone stepping /banding
                        2 If the plate imaging changes you don’t have to apply a curve on top of the one you’re using. Just modify the one you’re using.

                        Comment


                        • #27
                          Originally posted by Alois Senefelder View Post
                          Gentlemen of the Pre- Press Brigade,


                          "Raison d'etre" ...... is to produce - Production Compliant Imaged Lithographic Printing Plates.

                          Instead of talking endlessly among yourselves !!!



                          Regards, Alois
                          I love it when you talk nerdy...

                          Comment


                          • #28
                            Hello Slammer,

                            Thank you the........ Dubious Honour you bestowed on me !!!


                            Regards, Alois

                            Comment


                            • #29
                              Originally posted by Alois Senefelder View Post
                              Hello Slammer,

                              Thank you the........ Dubious Honour you bestowed on me !!!


                              Regards, Alois
                              y´Welcumz;.)

                              Comment


                              • #30
                                Originally posted by RickS View Post
                                Food for thought. Years ago we had a laser die in our CTP. We were down a couple days to replace. Because we were using a linear curve and a press curve, I was able to linearize and start making plates to get the presses running without having to do any press tests. Granted Lasers do not die often, but I like the linear curve method.
                                With a one curve workflow you don’t have to run a press test if, as in your example, your laser dies. You’d do basically the same as you did - apply a curve to bring the plate to the same tone response you had before. That’s what you did when you linearized your plate (before you applied your second curve) it’s just a press curve rather than a linearizing curve (prior to a second curve).

                                Comment

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