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Color Management - am I backwards thinking?

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  • Color Management - am I backwards thinking?

    good afternoon,

    i have a question regarding color management. I have been working in prepress for a long time, so i have a working knowledge of color and color spaces, and dot gain and so forth. I have never actually been very involved in the implementation of color management over an entire process, and we are currently at a crossroads at our facility in determining how to go about this. We are a medium-sized web printer (we have 8 webs) with a pair of sister companies of similar size. we have work that we share among ourselves, so it is important that we all get on board with each other, and have solid management in place. several of us have one idea about how color management can be approached, while the majority seem to have an opposite point of view. i ask this question from a neutral point-of-view, i am just interested to hear both sides of the equation from some others who have tackled this problem and conquered it.

    what we desire, naturally, is the ability to have the proofing devices calibrated amongst the 3 plants, so that a proof can be pulled confidently at each or any plant and know that it will match within tolerance to a similar proof made at the other plants. at that point, each plant is responsible for fingerprinting the presses and creating dot gain curves to be applied at output on the plates, to match the rendering on the proof. here is my question:

    would it be wiser to look at this problem from the printers point-of-view, where a proof is output with dot gain applied, and the plates are output linear, or does it make more sense to output linear proofs, and create press-specific dot gain calibration curves? i agree with the latter, but it seems that is a minority viewpoint. my thought is that if a file is created with a 50% dot, the proof should indicate a 50% dot. as a customer, if i design a piece that shows a screen tone of 50% magenta, i want to see a proof that accurately represents what i have created. then, as a print provider, it is YOUR job to compensate, through dot gain curves applied to the plate, and create a 50% magenta on the printed sheet. the other point-of-view seems, in my opinion, to tell the customer "we cant match what you want due to dot gain, so this is what it will look like instead".

    right now we are facing a world of curves and icc profiles and different color proofing devices between plants that seems to be very difficult. would it not be an effective, and much simpler, strategy to output linear proofs at all plants, and then place the responsibility of press curves to each individual plant to match the proof?

    thank you for reading, i am interested to hear different takes on this. i certainly won't be offended if you have strong opinions that are against mine, i just want to get the feel for where my thinking is wrong on this topic!


  • #2
    Re: Color Management - am I backwards thinking?

    Hi there,

    I think a important point to make is that the proof is a way of simulating press output. Your point about a 50 % screen being 50 % does sound logical. But i think photoshop would automatically turn any 50% tint into 70% on screen as it is set up to simulate SWOP conditions or whichever output profile is intended. The ctp/ rip could make curves to simulate linear conditions from the press output but it would look sh*t and you would have a 50% tint printing at 30-35% to achieve this. Dot gain is a inherent part of the process, there has to be some mechanical gain in dot size due to the transfer under pressure from blanket to substrate. I assume that if you design a tint of 50% in photoshop the reality is that you could be viewing a 70% tint with the compensation, not quite sure if thats true but but it makes sense. There are many ways to standardize output between devices and plants like the iso 12647 way. there should be lots of info on these forums to get you started.



    • #3
      Re: Color Management - am I backwards thinking?

      I will strongly agree to proof in a linear way, if everyone agrees this means a 50% value will read arounf 69% on proof. Any designer will expect his colors 20% stronger than life because that is what all of its softwares are color managed to show him. Press curves are definitely a must when outputting plates because press gain may not be exactly on the SWOP numbers. (like your proofer should be).


      • #4
        Re: Color Management - am I backwards thinking?

        This was kinda-sorta covered in a thread a while back...


        • #5
          Re: Color Management - am I backwards thinking?


          What kind of proofs are we talking about? Proofs aren't really "linear" or "non-linear".

          That being said - the easiest thing for you guys to do is to choose a standard (published or internal) to print to. Select (or create) a profile of that standard condition for proofing and separating to.

          Profile your proofing devices. Each proofing device will have a profile that describes it's behavior. Proofs will go from the standard color space (the one you've selected above) to the color space of the proofing device. The color space of the proofing device will be distinct to each proofing device.

          Calibrate each press to print to the standard condition (the one you've selected above). This will likely involve creating curves for your plating. Curves may or may not be distinct and individual to each press. If you have the resources to assure that the presses exhibit tolerably similar behavior then you'll simply have curves that correspond to papers and screens.

          Everything hinges on the selection of an appropriate standard printing condition.



          • #6
            Re: Color Management - am I backwards thinking?

            As Rich states the standard is the key. My advice would be not to travel down this road without the help of a G7 Expert such as Rich (he's an all around good guy also!)
            I have worked with Terry Wyse from Wyse Consul and the knowledge these guys possess (Rich included) truly does make them experts, and makes reaching your destination
            easier and cheaper in the long run!


            • #7
              Re: Color Management - am I backwards thinking?

              Hi Chris,

              There were a lot of good tips in the previous answers.

              Here is the simplest most sound thing you can say about printing:
              2 presses that print differently cannot use the same CMYK numbers to give you the same result.
              Your choices are either to *make the presses print the same*, or *give them different numbers* (percentages...).

              So, I think the main question here is:
              *Do you want to use exactly the same files for all your 3 locations?*
              This is the safest way to approach it. If the answer is yes then you have to make the presses print the same and that involves press fingerprinting, change in print densities, change in plate curves (compensate for different dot gain), and possibly change in blankets, inks, color sequence, etc.

              The second choice is to leave the 3 locations do what they do and give them different files (numbers/percentages).
              For that you need a good quality workflow in place (that could manage color management transparently) and maybe you need to change the way you work in prepress. Activate color management in each app you use. Prepare the files on calibrated monitors and try not to rely on your past experience with CMYK percentages but on the visual feedback from the monitor. Try to keep the numbers in RGB (both vectors and bitmaps). Profile each press at each location, and embed the profiles in the workflow. Set your workflow at each location to convert the numbers in the files to the CMYK numbers needed for each press.
              Do you think this path is simple enough for you? This is what color management can do for you but there are a lot of caveats, too many to enumerate, the main one being that you still have to maintain the presses running as close as possible to the printing parameters used to create the ICC profiles. Also you need separate profiles for different media types (coated, uncoated).

              About proofs and proofers. Linearizing and profiling the proof has nothing to do directly with your printing conditions. It is just to describe to a color management engine how the proofer prints. So as long as each proofer is able to reproduce all the color gamut of your printing they don't have to be calibrated exactly the same. After profiling the proofer, you also need the ICC profiles for your press.

              The simplest way, in my opinion, is to decide for a common printing standard among all locations (as somebody already suggested). And if you do that then maybe the best option is the new Gracol G7 or the new SWOP. And that is equivalent to the first choice.

              Good luck,


              • #8
                Re: Color Management - am I backwards thinking?


                thank you very much for the answers. i have read each carefully, as well as the linked topic that was mentioned above, and they have been very helpful. i am beginning to better understand the overall scope of the situation as it applies to us. when i have a few minutes, i will add more to this reply, but for now, thank you for all of the input!



                • #9
                  Re: Color Management - am I backwards thinking?

                  Hi Chris,

                  I would agree with the others that you need to settle on a standard first and then go from there however I would like to recommend what we do here, which is G7. One big advantage I see here with G7 is having some latitude on press to compensate for some day to day or week to week, whatever the case may be, drift or variation in the press. The press still needs to be maintained as close to its optimum printing condition as possible, but if there has been minor variances, or different shades of paper, IF the pressman can still achieve gray balance by varying densities slightly AND the Lab solids stay within tolerance, we have found we will match the proof pretty good.

                  We only run one sheetfed press here but I would imagine the same would be true with multiple presses, the same file printed on different presses, as long as they aren't really far apart to start with, will have a close appearance to the proof as long as gray balance and neutral density, as defined by G7, can be achieved and the Labs are within tolerance.

                  One other thing we've done is create a copy of the standard Gracol profile but with max GCR, I believe this allows us to better achieve and maintain gray balance since we're getting rid of most of the CMY mix and replacing it with just K.

                  Just what we do here, there are many ways to go about this, the main thing is to get everyone on the same page and understanding the process.



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