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Curve4 - Indigo Press

  • 1.  Curve4 - Indigo Press

    Posted 06-22-2018 04:27 PM
    Hello Group, trying to create new LUTs for our Indigo press. I think I'm missing a step in Curve4 and would like to ask the group for help. I'm following the instructions on pages 55-57 of the Curve3 user guide (cant find a updated guide).
    The steps I'm taking are as follows...
    1. Stabilize the system (calibrate press)
    2. Make a sample print (no color management)
    3. Measure P2P51 target (using eye-one iSis)
    4. Load measurement files into Curve4 (in Calibrate section)
    5. From Curve4 software, go to Create Curves tab and export Indigo Files (LUTs).
    6. Apply the new LUTs and printout a new target.

    The new target looks terribly washed out. I feel like I'm missing something with the Control Points.

    Any help is greatly appreciated.
    Kind Regards,

    ------------------------------
    Robert Hunt
    Prepress Mgr
    Linemark, Inc.
    Upper Marlboro MD
    (301) 925-9000
    ------------------------------


  • 2.  RE: Curve4 - Indigo Press

    Posted 06-24-2018 08:16 PM

    Do you have the correct target color space set in Curve4?  If you have CPRC3 as the target and you really want CRPC6 then you could get some washed out results.

     


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    Daniel Hutton

    Project Manager

    Carter Printing Company

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    804.359.9206 x 305

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    carterprinting.com

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    dhutton@...

     

     






  • 3.  RE: Curve4 - Indigo Press

    Posted 06-25-2018 01:33 AM
    It sounds like you may be starting out with nominal TVI curves already in place.

    When the correction is calculated from a curve that already includes dot gain, it is likely to be a small correction in the 2-3% range, and when that is imported into the Indigo it will be virtually linear...about 17% too light.

    In order to import corrected LUT’s into the Indigo, start off with linear curves. The P2P’s will look very light, but Curve will calculate the required correction.

    Sent from my iPhone




  • 4.  RE: Curve4 - Indigo Press

    Posted 06-25-2018 09:13 AM
    Robert,
    Sounds like your first print already had a curve applied, even though color management was off.  If this curve was replaced by the curves generated by Curve4, your results could look too light or too dark.
    Double-check that no curve is active when printing the first P2P.

    Daniel,
    The target color space in Curve4 has zero effect on how the calibration curves are generated. It only affects the Verification metrics.

    ------------------------------
    Don Hutcheson
    HutchColor, LLC
    Washington NJ
    908-500-0341
    don@...
    ------------------------------



  • 5.  RE: Curve4 - Indigo Press

    Posted 06-25-2018 01:51 PM
    Think i'm getting closer. How do I load the 075LUT as the starting print condition in Curve4?
    Is their a folder I need to put the 075LUT text file into so it's available in the CRPC drop down menu?
    Am I only supposed to use canned CRPCs?

    075LUT starting print condition

    ------------------------------
    Robert Hunt
    Prepress Mgr
    Linemark, Inc.
    Upper Marlboro MD
    (301) 925-9000
    ------------------------------



  • 6.  RE: Curve4 - Indigo Press

    Posted 09-19-2018 02:02 PM
    Robert - how did your Curve 4 and Indigo experiment work out? We are in the same boat - just cannot get it to work and what we achieve seems to be very similar to your results.

    Mike

    ------------------------------
    michael stewart
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  • 7.  RE: Curve4 - Indigo Press

    Posted 27 days ago
    Solving G7 calibration problems on HP Indigo:

    Some people report that after calibrating an HP Indigo the results are to light. This is usually because they printed the initial target (e.g. P2P51) with a calibration curve in place, for example the 075 LUT, but did not select that curve in Curve4's "Based On" list.

    There are two solutions:

    1.  The easiest solution is to print the initial target with the "Linear" LUT selected in the HP RIP.
    2.  Another solution is to load the values of the starting LUT into Curve4's "Based on" menu.
         The challenge with solution 2 is to create a text file containing the starting LUT nodes.
         This is explained in the Curve4 User Guide in section 3, under Re-Calibration (Iteration), starting on page 77.

    Also note that a new P2P53 target improves gray balance accuracy when starting with the HP Linear LUT. The P2P53 can be had by contacting me, don@....

    ------------------------------
    Don Hutcheson
    HutchColor, LLC
    Washington NJ
    908-500-0341
    don@...
    ------------------------------



  • 8.  RE: Curve4 - Indigo Press

    Posted 26 days ago
    I can chime in here as well. I found poor results when starting with Indigo linear luts.
    Yes it's easier but P2P is way too light to accurately calculate NPDC without multiple rounds of curve iterations.

    Much better results using the the Indigo's default exp05 lut. I made a simple text file for Curve to base the adjusted NPDC off of by just looking at the exp05 lut nodes on press. This process gets to tight G7 in no time. Especially now that it's getting done with the FD-9 spectro.

    Hope this helps.

    Eric DeRoos
    Director, Premedia | G7 Professional
    Wright Business Graphics
    800.547.8397
    971.804.2314 - Cell
    SOC2 Security | G7 Master Printer | wrightbg.com




  • 9.  RE: Curve4 - Indigo Press

    Posted 25 days ago
    The P2P53 target has now been added to the P2P51 package at ...


    It will soon be available on the Idealliance website too.
    In the past 48 hours I have had around 25 requests for the P2P53 target.  This will save me having to reply to each request individually.

    Thanks,

    Don

    **************************
    Don Hutcheson
    President
    HutchColor, LLC
    908-500-0341
    **************************










  • 10.  RE: Curve4 - Indigo Press

    Posted 26 days ago
    The P2P53 target is designed to overcome inaccuracy experienced when starting from the Linear LUT with the P2P51.  It effectively applies something like the 075 LUT within the target.

    Yesterday I added the P2P53 target to the P2P51 package available at ...

    http://www.hutchcolor.com/Images_and_targets.html

    So there's no longer a need to contact me directly to get it.

    I also updated the P2P51 sub-package to include versions for the DTP70 and Barbieri LFP, as well as miniP2P versions of the P2P51 and P2P53.
    Right now the miniP2P is only compatible with Curve4, and the P2P53 requires the latest release of Curve4.

    ------------------------------
    Don Hutcheson
    HutchColor, LLC
    Washington NJ
    908-500-0341
    don@...
    ------------------------------



  • 11.  RE: Curve4 - Indigo Press

    Posted 09-20-2018 06:25 AM
    Edited by Danial Hahn 09-20-2018 06:28 AM
    Hey Robert,

    i would reach out to Don H

    ------------------------------
    Danial Hahn
    Print Service Tech Sheet Fed
    Hubergroup USA, Inc.
    Greensboro NC
    (850) 736-2033
    ------------------------------



  • 12.  RE: Curve4 - Indigo Press

    Posted 09-21-2018 06:54 AM
      |   view attached
    Hi Robert

    The problem is that you printed the P2P with a darkening curve already installed in Indigo, then replaced it with curves generated by Curve4. But because Curve4 didn't know about the original curves, the new curves will not apply the same darkening.

    There are two solutions:

    1. The easiest way is to select the "Linear" curve in Indigo and print the new P2P53 target (attached here I hope!)
        The resultingHP Indigo file set generated by Curve4 should then work correctly.

    2. Print the P2P51 with Indigo's 075 LUT and measure into Curve4.
        Copy the 075 LUT values into a text file (see "Creating and importing an Initial Curves file" Curve4 User Guide page 74).
        In the Curve4 Run, select the 075 text file in the "Based-On" menu.
        In Create Curves, export the HP Indigo file set.
        The resulting curves will replace the 075 LUT and again, should work correctly.

    If you can't find the P2P53 target, contact me directly and I'll send it by email.

    ------------------------------
    Don Hutcheson
    HutchColor, LLC
    Washington NJ
    908-500-0341
    don@...
    ------------------------------

    Attachment(s)



  • 13.  RE: Curve4 - Indigo Press

    Posted 09-21-2018 11:16 AM
      |   view attached
    Don beat me to it -- and verified that I am doing it right (thanks, Don).

    In the ticket template, under Color tab, in Separations pop-up . . . I set "Default job LUT for separation" to "linear".

    I originally did this by trial/error and intuition. I think I got unexpected results like you are, but I don't remember exactly. Later I talked with an HP rep. and he said this is the proper way. It makes sense to me now. You want "bare metal" for your calibration run. Let Curve make all of the adjustments.

    ------------------------------
    Doug Kiley
    Lynx Group, Inc.
    Salem OR
    (503) 588-9339
    ------------------------------



  • 14.  RE: Curve4 - Indigo Press

    Posted 09-21-2018 12:11 PM
      |   view attached
    I have not seen documentation from HP on how to calibrate to G7 so my process has been developed with trial/error and educated guesses.

    Another thing I stumbled upon is setting the printing standard of the CMYK workflow to GRACoL2006. If I didn't do this then one of my process color solids didn't meet dE spec. I believe it was magenta. After turning this on I then noticed there were specs of mixed color in the solids. I think it was cyan in the magenta. Now all solids pass and with the curves applied the press passes Colorspace verification.

    Another tip: When the colors look bad don't jump to doing another G7 calibration. Have your operators check the condition of the press. Do a color cal (or 2). Check that paper definitions are right. Check their ink/oil balance. I've had the same curves on our Indigos for 18 months.

    ------------------------------
    Doug Kiley
    Lynx Group, Inc.
    Salem OR
    (503) 588-9339
    ------------------------------