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  • G7

    Has anyone experience of running G7

  • #2
    Re: G7

    Sure. Any thing specific you are looking for?

    Comment


    • #3
      Re: G7

      Peter

      You must mean has anyone experienced printing to ISO 12647-2 using the G7 Calibration method ?

      If that is your question then Yes, what exactly are you looking for ?

      There is plenty of Information on the Gracol Website on how to.....WWW.Gracol.org

      John

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      • #4
        Re: G7

        Sorry for my vague question - what I realy wanted know was how many people are running G7

        Peter

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        • #5
          Re: G7

          Peter

          If you go the Gracol website, look for "Find a G7 Printer" and you can get an idea of how many people
          are doing it.
          Looks like there are over 100 company's that are listed as G7 Master Printers and Im sure that there are some
          that are not certified .

          John

          Edited by: John Romano on Dec 19, 2007 11:43 AM

          Comment


          • #6
            Re: G7

            I am interested to know what control strips you use to get to the correct colour on a job and how you control it on the run.

            Do you only use grey balance etc

            Peter

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            • #7
              Re: G7

              Peter,

              We have been running G7 for about 6 months. We have tried different versions of colorbars and what we have now is probably what we will stick with. I have the KCMY solids of course, a 50% K to measure for density, and a 50%CMY to measure for density, and a CMY patch to check gray balance. We are doing this with a Tobias scanning densitometer, setting it up to read the 50%CMY and 50%K patches as K density to control the lightness/darkness of the gray and the 50%CMY to control gray balance.

              We tested and found what densities gave us the right solid Labs, read the P2P scales and created curves from that. Now we use those same curves for every paper, adjust densities to achieve gray balance, correct darkness and check our Lab solids, if all are in tolerance, its worked. We mostly run on coated and matte coated or silk and have found that we can use the same curves for those and stay within the tolerances with just density changes.

              I really like the idea of being able to do that. So far 2-3 different ink companies, 2-3 different kinds of paper (don't think we've ran any uncoated color work though) all with same profile and curves and still hit within the G7 tolerances.

              We were using custom press profile before and would have had to have different profiles for the different papers I think because the dot gains were so different on some papers. Only thing I've done different is take the G7 profile in Profilemaker and use MaxGCR. This seems to work fine for us, less color ink used, less color shifts on press, and only seems logical to me, if trying to achieve gray balance is the most important goal in G7 to avoid color casts, that if I'm mostly or only using black ink in neutral\gray areas, I will achieve and maintain gray balance easier? I always want to learn more and\or better ways so if someone knows why I shouldn't do this, please tell me.

              Terry

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              • #8
                Re: G7

                I dont have any problems with what you say - the only difference I think is that we get to the grey balance in a diffrent way - and the TVI gain is a little less. - but I bet sometimes in the heat of battle we would meet somewhere. I have enclosed the above elsewhere - but I will do it agin - its a report of one of my press runs - it shows the grey balance which you can see we missed the 75% - I think becuase we have deropped our 75% TVI .Like you I run this printing condition on all paper types apart from Uncoated

                Comment


                • #9
                  Re: G7

                  Hi Peter ,

                  I'm curious, where do the targets for gray balance for 25, 50 and 75% come from (I'm assuming from the black scale, yes)? Seems rather bluish.

                  Comment


                  • #10
                    Re: G7 (and GCR)

                    Terry, You state that you modified the actual Gracol profiles to maximum GCR. At what Cyan level starts K? Or at what L level?
                    Your observation (best results with max GCR) is identical to our.
                    GCR is, in my opinion, a very important part of our system to stabilize color during production.
                    For the printer, the problem of simulation Pantone colors by CMYK process percentages stil will exist. If the designer took the CMYK values from a guide, he most probably will get CMYK combinations with a limited amount of GCR. Or less K and more CMY. How do you handle these Pantone Process colors? Any Device Link Profile transformation?
                    As Peter stated in an earlier report, for some customers the color tints (such as logo's or corporate colors) are sometimes even more important that the actual images.
                    regards, Henk

                    Comment


                    • #11
                      Re: G7 (and GCR)

                      Henk,

                      I think from what I looked at just now, my K starts at 0 because in Profile Editor under Profile Info it says:

                      Separation: MaxK-0-100-79/72/72/100

                      its been a while since I did all this so best I remember, I think that's what it is?

                      As far as Pantone, I'm in a special case here in that we create all our own files in house, so I have the luxury of providing everyone with my color settings and we use an RGB workflow. Within that, if a certain PMS color is chosen, we use Photoshop and the solid to process picker to get the cmyk values and just use those in Indesign to create the file.

                      I guess you could pick it in Photoshop and then get the Lab values or RGB values and convert those to your high GCR profile to get those numbers. How well that may match a certain PMS color, I don't know, probably like most any, some better than others.

                      It always depends on the job, if we have to match something really close and over time (reprinting) we generally go with a PMS spot ink instead of going process.

                      Terry

                      Comment


                      • #12
                        Re: G7

                        Hi Peter,

                        Sorry to cut in. Just noticed that your using PressSign from the PDF report you posted here.

                        I've just discovered it and it looks like it makes it a lot more intuitive to perform an ISO 12647-2 calibration.

                        Can I ask you a few questions?:

                        # Did you use the curve export function of PressSIGN or the IdealinkCurve to generate your RIP curves?
                        # It doesn't seem to offer 'zone by zone' advice for each colour. (Like your cyan is too low in this zone, but magenta is ok for the same zone, yellow, black etc.) It just appears to have an overall cyan is too low, black is too high.

                        How does your press operator know to tweak specific zones for each colour, in order to get the entire press sheet to be compliant.

                        (I may not have explained this clearly)

                        Thanks for any info...

                        Comment


                        • #13
                          Re: G7

                          We were qualified as a G7 master last August. We run a color bar at the tail with solid CMYK patches, A 50% Black patch, Red, Blue and Green overprint patches and 50% Cyan-40%Magenta-40%Yellow for the gray patch. We also run our standard color bar at the gripper with additional 25%,50%and 75% patches of each color.
                          When running we check the gray patch and if there are issues or need very fine control we read the other patches. The other patches are necessary to trouble shoot and maintain press integrity in case something doesn't match and you need to back to pre press.
                          When we originally tested for G7 we were trying to use the Idealliance curve but settled on a custom profile to match more closely. We also had to switch inks to match the ISO standard for color. We have since found several inks that meet the standard.
                          After running for eight months, G7 has definitely helped our shop match proofs better and control color easier on press.
                          The thing to keep in mind is the process is another tool to help us get better. If you do not calibrate regularly or maintain your equipment properly, you will struggle. If you consistently pay attention to details it will be easy for you and you will enjoy great proof to press matches.

                          Todd

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