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Plate Calibration - Harlequin RIP - Edit From Calibrated/Uncalibrated

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  • #16
    So i am thinking the best (and simplest) approach would be to...

    1.) Run a set of plates with no settings in any of the curves.

    2.) Measure the values of those plates.

    3.) Adjust accordingly using a single tone curve.

    4.) Repeat step 3 if required further.

    It completely makes sense to just adjust at the end of process...so much more efficient.

    Also thank you Ulrich for recommending ESKO i shall take a look...but in the mean time i have managed to configure a page setup to output TIFF's that i can view in Photoshop, this alone is very useful in seeing how any adjustments affect the output from the rip before it is plated.
    Andy Barrington
    barringtonprint DESIGN | PRINT | WEB www.barringtonprint.com

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    • #17
      Originally posted by andy_baz View Post
      So i am thinking the best (and simplest) approach would be to...

      1.) Run a set of plates with no settings in any of the curves.

      2.) Measure the values of those plates.

      3.) Adjust accordingly using a single tone curve.

      4.) Repeat step 3 if required further.

      It completely makes sense to just adjust at the end of process...so much more efficient.

      Also thank you Ulrich for recommending ESKO i shall take a look...but in the mean time i have managed to configure a page setup to output TIFF's that i can view in Photoshop, this alone is very useful in seeing how any adjustments affect the output from the rip before it is plated.
      1.) Run a set of plates with no settings in any of the curves. No curves.

      2.) Don't measure the values of those plates. The only need for measuring plates is to ensure that the plates image consistently - it is not for creating press tone curves. If your plates are not imaged consistently then you cannot build curves since you will be trying to hit a moving target,

      3.) Don't adjust accordingly using a single tone curve. Don't bother with the tones on the plates - you are selling presswork not plates. What happens tone-wise on the press is what's important not what happens tone-wise on the plate.

      4.) Don't repeat step 3 if required further. If you do it the right way it is unlikely that you will need to make any adjustment to your tone curve.

      What you do - if your plating is consistent - is to:

      1 have a target - a desired tone reproduction in your presswork
      2 output your tone patches to your plate. Do not apply any curves. It is preferable not to include images as that may confuse the press operator.
      3 run on press at your target densities/Lab values or whatever
      4 measure the tones in your presswork.

      You should be able to enter the tone values you got in your presswork into your RIP. The RIP then compares what you got to what you wanted and using that data builds a compensating tone curve that remaps the tones in your source files so that they will deliver your target tones in your press.

      5 do a confirmation press run with the compensation curve calculated by the RIP
      6 Celebrate success

      NB you can see a more detailed version of the process here: https://the-print-guide.blogspot.com...pensation.html
      Last edited by gordo; 07-16-2019, 11:42 AM.

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      • #18
        Originally posted by gordo View Post

        That is not actually true. If you use a curve to linearize the plate and then apply a second curve to achieve your desired tone reproduction on press then you run the risk of introducing shadestepping (banding). Also, you've introduced another process variable - i.e. potential point of failure - with no benefit.
        Thank you again Gordo for this lesson. I really appreciate it as such. Banding is a phenomenal issue I never noticed in practice since the end of the 90ies with gradients out of quark xpress-files and I don’t think that Andy has problems with that although he works with linearized plates till now...

        i remember the risk of banding as a strong argument for the FM-profiles when they had been published about ten years ago: “when the files already are converted into the FM-profiled separations in which the remarkable higher increase that come with FM is already respected, there is no longer a need for such strong compensation curves in the RIP you will need as by working with FOGRA39-separated files you want to print with FM...”

        So, does it really matter a difference when you take two curves or only one for such a strong compensation curve at least? I do not understand the difference, but that’s not the point here... ;-)


        Originally posted by gordo View Post
        Does the "manual" include definitions (a glossary) for the terms it uses (e.g. "calibrated target", monochrome, etc) when building tone reproduction curves? If so I'd like to see it (couldn't find anything on the web).
        i find only this in the www (now at home typing in a smartphone...), may be the search in Acrobat will do the job of a glossary, hope the link works:

        http://xitron.com/downloads/support/...r%20Manual.pdf


        Ulrich

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        • #19
          Now we have really fun together:

          Originally posted by gordo View Post
          You should be able to enter the tone values you got in your presswork into your RIP. The RIP then compares what you got to what you wanted and using that data builds a compensating tone curve that remaps the tones in your source files so that they will deliver your target tones in your press.

          5 do a confirmation press run with the compensation curve calculated by the RIP
          that is exactly what Andy did already with curve 3 (Target/Intended press) and curve 4 (press curve via left button “Edit from uncalibrated target”) and what leads him to a result 5-8% above the target.
          The only difference to your recommendation is that he uses a linearization (curve 1), too, which really does not matter in this case. It is for sure not the effect of the linearization curve what leads him to a higher result as aimed in the harlequin dialogue ...

          Originally posted by gordo View Post
          6 Celebrate success
          That is what he want!

          Ulrich
          Last edited by Ulrich; 07-16-2019, 12:46 PM.

          Comment


          • #20
            Originally posted by andy_baz View Post
            So i am thinking the best (and simplest) approach would be to...

            1.) Run a set of plates with no settings in any of the curves.

            2.) Measure the values of those plates.

            3.) Adjust accordingly using a single tone curve.

            4.) Repeat step 3 if required further.

            It completely makes sense to just adjust at the end of process...so much more efficient.

            Also thank you Ulrich for recommending ESKO i shall take a look...but in the mean time i have managed to configure a page setup to output TIFF's that i can view in Photoshop, this alone is very useful in seeing how any adjustments affect the output from the rip before it is plated.
            Apologies I misled you in this message...

            when i said measure those plates I meant measure those values of that plate when printed.

            i beleive we are now talking the same method
            Andy Barrington
            barringtonprint DESIGN | PRINT | WEB www.barringtonprint.com

            Comment


            • #21
              Originally posted by Ulrich View Post
              The only difference to your recommendation is that he uses a linearization (curve 1), too, which really does not matter in this case.
              You probably say "12 noon" instead of just "noon" (the 12 is redundant) ;-)

              In lean manufacturing terms the 2nd most common wastes is excess processing. Excess processing is a sign of a poorly designed process. A redundant step like applying a curve to linearize plates before applying a second curve to affect tone reproduction in presswork is an example of excess processing.

              You gave a good reason for why linearizing the plate is probably a carry over from the old film to plate days and that is no reason to continue doing it. So, I'm just being more adamant about removing redundancy and making the process as simple and variable free as possible.

              Comment


              • #22
                I totally agree to your strategy to make a clean up concerning redundant steps!

                The only reason I said, that it does not matter that Andy has worked with the linearization curve in this actual case is this, my understanding (no scientific or mathematical knowledge) of the process we are talking about:

                Working with the Harlequin RIP the use of a linearization curve has nothing to do with the compensation curve the RIP is generating for the print with the input from a target (curve 3, intended press) and curve 4 (actual press curve). Although the RIP generates another compensation curve (for linearization of the plate) and “combines” both compensation curves at least, but that combining happens probably in a simple addition compared with a more complex
                algorythm which is used for generating the compensation-curves.

                I understand the generating of each compensation curve as autonomously processes.

                The proof for this thought is simple: a plate only with curve 1 (linearization) and curve 3 (intended press/target) will lead to the same result as a plate made only with curve 1.
                The use of curve 3 only make sense with a curve 4 (actual press). Following this argument the use of curve 4 also make sense only with a curve 3 together and therefore a plate made only with curve 4 and curve 1 leads to the same result as a plate only with curve 1. And that is the proof that the use of a linearized curve (1) does not affect the compensation curve made from the input from the curves 3+4.

                If so... unfortunately I can not proof it anymore by testing. But from this thoughts I find the courage to claim that in this special case it does not matter and has no influence that Andy got a result +5-8 above target by working with curve 3+4 (and 1). Did he got the same results he got from the linearized print without a linearized plate he had got also +5-8 only by using curves 3+4...

                Ulrich

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