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no0b question for the experts in color

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  • no0b question for the experts in color

    I've been in printing for about 3 years now. I don't know too much about color management but I am doing lots of research on it. I'm working at a company now that lost it's pre-press manager and we now need to calibrate our press/proofers. For whatever reason the boss man wants us to re-calibrate every 6 months. We are now at that point of re-calibrating. This is all new to me since the last shop I worked at was very simple and I figured out (on my own) how to calibrate the HP5500 they had to match the press. It was very straight forward because he had a BestColor XXL RIP hooked up to his HP. That pretty much simplified everything for me, but then again I knew nothing about color management and the color was probably way off since I didn't know about any standards (G7/SWOP). Now I'm playing a whole new ball game here.

    So were to begin...

    We have the Brisque client, an HP5542, an Approval XP4 and ProfileMaker 5. Right now I am studying GRACoL7 since that is what the pre-press manager set as a standard here. The press' we are trying to color manage are a Heidelberg 6/40 and a Komori 6/28. I have set up 2 layouts for both press'. We will be running uncalibrated plates soon for the first run.

    Question 1:
    Do I run linearized plates (with an Ex-Curve) when we do the first run? Or don't run linearized plates at all during the calibration process?

    Question 2:
    How do I go about linearizing our HP5542? Or do I even need to? It has a "Color Curve" applied to it now so I am assuming yes on linearizing it. Or maybe a "Color Curve" is not the same as linearizing?

    I'm sorry for the stupid questions and I'm sure there will be plenty more to come as we progress into this fun filled experiment. I thank you all VERY MUCH in advance for any kind of help you can give me.

  • #2
    Re: no0b question for the experts in color


    No stupid questions.

    Okay, first the 5542. Linerization of this device depends on the front end. It's got some internal calibrations, head alignment, et cetera; but the linerization is handled by the RIP driving it.

    Sorry, can't help you on the Approval. You can look up the Application Data Sheet on it, though.

    Onto the press. Well, the stupid answer is this: you want to get to a REPEATABLE state on your plates. Doesn't have to be linear, but it does have to be repeatable and controllable. Don't just spit out plates, but for instance, if I have access to the laser power of the platesetter, I'm a fan of adjusting the laser to control "linearization". I've done this at two locations - one of which was on a Brisque front-end. Now, some boxes, like the Creodak Trendsetters, don't allow you to control the laser power - so, linearization must be handled in the front-end with "Ex-curves". Repeatability is more important than linearity. Linear makes process control easier, though.

    Do one press a day. You want to run the (second) confirmation run immediately following the first (raw or linear) run. You definitely want to do the second run. If you don't, you'll be hurled into G7 hell, where you'll be forced to wear flea-infested, fur undergarments for a hot, humid eternity.



    • #3
      Re: no0b question for the experts in color

      Thank you Rich for your speedy response.

      I am familiar with the internal calibrations on the 5542 and I go through them each time I change a head or cartridge, just to make sure everything is in line. But the RIP that we have driving it (Brisque) doesn't have any software built into it (at least that I know of) to make linerization easy. So what I was doing was printing off the Press2proof 21 form from Gracol and using there chart to see what kind of color-curve/TRC I needed. It seemed to work somewhat but when I printed out a test sheet with only the color curve applied it seemed like the colors were very light in mid and low tones. But, the 50% black and the CMY grey seem to match dead nuts. So I'm thinking that this color curve will work, and when I profile my HP to match my Approvals it should bring the colors back up right?

      I have had someone from Kodak come in and show me how to calibrate the Approval so I think I have that part down. We where scheduled to have 2 days with her but I only took one day for now and am going to have her come back as soon as I run into something I can't figure out.

      I'm not sure about adjusting laser power on our Lotem 800. But I know we can apply ex-curves to our workflow. So I think that's what I have to work with for now. I guess it doesn't matter if I apply an ex-curve to the first round of plates as long as I apply the ex-curve to the second (confirmation run) round of plates as well right?

      I was under the impression that we must do a confirmation run following the first run in order to make sure our neutrals and colors are where we want them? I feel like I have already been hurled into G7 hell!!! :-P

      Thanks again.


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