Discussion: View Thread

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.

     


    https://carterprinting.com/sites/default/files/manualfiles/email/carter-email-signature-logo.png

    Daniel Hutton

    Project Manager

    Carter Printing Company

    o:

    804.359.9206 x 305

    w:

    carterprinting.com

    e:

    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 28 days ago
    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
    ------------------------------



  • 7.  RE: Curve4 - Indigo Press

    Posted 28 days ago
    Edited by Danial Hahn 28 days ago
    Hey Robert,

    i would reach out to Don H

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



  • 8.  RE: Curve4 - Indigo Press

    Posted 27 days ago
      |   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)



  • 9.  RE: Curve4 - Indigo Press

    Posted 26 days ago
      |   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
    ------------------------------



  • 10.  RE: Curve4 - Indigo Press

    Posted 26 days ago
      |   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
    ------------------------------