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Description

This KB describes how you can verify during production if the printing condition is within tolerance. We call this "process control".

Procedure

Process control when printing according to the ISO12647-2 standard (TVI match)

Press calibration (= fingerprinting)

Process control is done AFTER the press calibration procedure which will not be explained in detail in this KB. But in short, a press calibration is the process which standardizes the printing condition according to an in-house or industry standard. An example of an industry standard is the ISO 12647-2 which describes the target and tolerance values for the offset printing process.

The end result of a press calibration is typically a set of target density values (but could also be Lab values) for the process colors (used by the press operator) and a dot gain compensation curve (applied in the RIP when outputting a production job). Such a dot gain compensation curve is (typically) calculated by PressSync after measuring the dot gain of a P2P25 chart printed without any curve.

Left graph: the desired dot gain for production 
Graph in the middle: the measured dot gain when printing a job which is ripped without any press curve
Right graph: the calculated compensation curve to achieve the desired dot gain

PressSync will save the dot gain compensation curves in a curve set (*.prsync). It's this curve set which is the starting point for a process control with PressSync. Of course, one can also do process control by using a default curve set (without a compensation curve) but then you only do "a check" to verify if the printing condition is within tolerance. But typically you want to check AND update the current compensation curve if needed (which requires a curve set with compensation curves).

This KB describes the steps of a "check and update" procedure.

Process control procedure

  1. Open the PressSync curve set you used for the press calibration (so the curve set WITH compensation curves).
    Which curve set was used for the press calibration?
    Open the RIP ticket (e.g. Image to Screened Separations), the name of the curve set is shown as Curve Strategy for the Default Press Curve option (Separations tab).
  2. Go to the Measure menu and select Measure Automatic.
  3. Select from the Layout drop-down list, the type of control strip you want to measure.
    Consult below information (PressSync compatible strips, Control strips not compatible with PressSync , Custom control strips) to find the control strip for your needs.

    Select From Setup in case of a custom control strip
    Select "ESKO_Single_Ink_Control_Strip_Sep.it8" for both the Orange, Green, Violet and Blue Esko single ink strip (ESKO_Single_Ink_Control_Strip_Sep.pdf).

    There is only one layout which will automatically detect the OGVB inks.

  4. Click the Start button to start the measurement process and save the measurement data when desired (not required!).
  5. Repeat step 3 if you have multiple control strips. PressSync will automatically average the measurement data.
  6. Click the OK button to continue.
  7. Click the Go To Results button.
  8. Evaluate the result in the Overview Inks Solids window. Tolerances can be changed by clicking the Preferences... button.
    In this window we only evaluate the solids. Here is an overview of the substrate and solid process color tolerances according to ISO12647-2

    ISO 12647-2:2007
    PaperLab: +-3 / +-2 / +-2 (CIELAB Delta E (Classic) : M0)
    Lab: 4.2 (CIELAB Delta E (Classic) : M0)
    Cyan / Magenta / Yellow / BlackLab: 5 (CIELAB Delta E (Classic) : M0)
    Red / Green / BlueLab: 10 (CIELAB Delta E (Classic) : M0)
    ISO 12647-2:2013
    PaperPS1 ( * ): Lab: +-3 / +-2 / +-4 (CIELAB Delta E (Classic) : M1)
    PS2,3 - 8 ( * ): Lab: +-3 / +-2 / +-2 (CIELAB Delta E (Classic) : M1)
    PS= Print Substrate (PS1= Premium coated / PS2= Improved coated / PS3= Standard glossy coated / PS4= Standard matte coated
    PS5= Wood-free uncoated / PS6= Super calendered uncoated / PS7= Improved uncoated / PS8= Standard uncoated)
    Cyan / Magenta / Yellow / BlackLab: 5 (CIELAB Delta E (Classic) : M1)
    Red / Green / Blue(no tolerances)

    a

  9. Contact the press operator when one of the colors is out of tolerance!

Process control when printing according to the GRACoL specification using the G7 calibration method (Gray Balance aim)

G7 process control is not possible with PressSync. As an alternative, one can use the X-rite eXact Job Tool.

Download the G7 Job Templates here: https://www.xrite.com/service-support/product-support/portable-spectrophotometers/exact (Downloads > G7 Job Templates for eXact).

From PressSync, you can use the following G7 compliant control strips (located in \\Esko\bg_prog_intellicurve_v181\dat\doc):

  • ESKO_CMYK_Gray_Control_Strip_i1iO_1row_Sep_value
  • ESKO_CMYK_Gray_Control_Strip_i1_1row_Sep_value
  • ESKO_CMYK_Gray_Control_Strip_i1_2rows_Sep_value
  • IDEAlliance ISO 12647-7_Control Strip 2009
  • IDEAlliance ISO 12647-7 Control Wedge 2013

G7 compliant control strips contain the following patches:

  • HC: 25/19/19
  • HR: 50/40/40
  • SC: 75/99/99


PressSync compatible strips:

NameCompatible Spectrophotometer Use caseLocation
Control strips for CMYK printing
ECI_GrayConL_v2i1, i1iO
  • Should ONLY be used for the implementation of ISO12647-2:2007 PT1&PT2!
    (Use the curve set template "cmyk_ISO_PT1&2")

  • The three gray balance patch pairs serve as an "early warning". The chromatic gray patch should visually match the true gray patch!
  • R, G, B and CMY patches are used for the overprint evaluation. They reveal ink trapping problems.
  • Halftone patches are used for the TVI evaluation.

Consult this PDF for more information:
http://www.eci.org/_media/downloads/eci_bvdm_gray_control_strip_2012/eci_bvdm_graycon_doc_eng_v2.pdf

Gray BalanceOverprintTVI
Basic
(2 points)
YESYES
(10,20,30,40,50,60,70,80,90,100)

http://www.eci.org/en/downloads
See paragraph:
"ECI bvdm Gray Control Strip (older versions)"
> eci_bvdm_gray_control_strip_2012.zip

Use the PDF "ECI_GrayConL_FOGRA39_v2 inside the folder FOGRA39!

ECI_GrayConM_v2i1, i1iO
  • Should ONLY be used for the implementation of ISO12647-2:2007 PT1&PT2!
    (Use the curve set template "cmyk_ISO_PT1&2")

  • The three gray balance patch pairs serve as an "early warning". The chromatic gray should visually match the true gray patch!
  • R, G, B and CMY patches are used  for the overprint evaluation. They reveal ink trapping problems.
  • Halftone patches are used for the TVI evaluation.

This version should only be applied when there is not enough available space on the paper format for the application of version “L”. The halftone patches have an increment of 20%.

Consult this PDF for more information:
http://www.eci.org/_media/downloads/eci_bvdm_gray_control_strip_2012/eci_bvdm_graycon_doc_eng_v2.pdf

Gray BalanceOverprintTVI
Basic
(2 points)
YESYES
(20,40,60,80,100)

http://www.eci.org/en/downloads
See paragraph:
"ECI bvdm Gray Control Strip (older versions)"
> eci_bvdm_gray_control_strip_2012.zip

Use the PDF "ECI_GrayConM_FOGRA39_v2 inside the folder FOGRA39!

ECI_MediaWedge_v30
ECI_MediaWedge_v30a
ECI_MediaWedge_v30b
i1, i1iO
  • Primarily used for contract proof verification (ISO12647-8)
  • Can also be placed on a press sheet:
    • to use as a control strip (takes a lot of place!)
    • to use as a reference for a contract proof verification
  • Different layouts exist for spectro compatibility. PressSync can read all these layouts with both i1 and i1iO
    • v30: 6 x 6 mm patch size without a gap
    • v30a: 8.5 x 8 mm patch size with a gap
    • v30b: 6 x 7 mm patch size with a gap

Consult this pdf for more information:
https://www.fogra.org/index.php?menuid=35&downloadid=772&reporeid=0

Gray BalanceOverprintTVI
NOYES (no CMY patch)YES
(10,20,40,70,100)
Must be purchased via Fogra:
http://www.fogra-shop.com/
eskostripi1, i1iO
  • A basic control strip with two TVI points
Gray BalanceOverprintTVI
NOYES (no CMY patch)Basic
(40,70,100)
x:\Esko\bg_prog_intellicurve_v1xx\dat\doc
ESKO_CMYK_Gray_Control_Strip_i1iO_1row_Sep_valuei1iO
  • A single row strip to verify TVI and Gray Balance
    (i1iO compatible)
Gray BalanceOverprintTVI
YES (6 points)YESYES
(10,25,50,75,90,100)
x:\Esko\bg_prog_intellicurve_v1xx\dat\doc
ESKO_CMYK_Gray_Control_Strip_i1_1row_Sep_valuei1
  • A single row strip to verify TVI and Gray Balance
    (i1 compatible)

Gray BalanceOverprintTVI
YES (6 points)CMY patch onlyYES
(10,25,50,75,90,100)
x:\Esko\bg_prog_intellicurve_v1xx\dat\doc
ESKO_CMYK_Gray_Control_Strip_i1_2rows_Sep_valuei1
  • A two row strip to verify TVI and Gray Balance
Gray BalanceOverprintTVI
YES (6 points)YESYES (10,25,50,75,90,100)
x:\Esko\bg_prog_intellicurve_v1xx\dat\doc
Control strips for expanded gamut printing (Equinox)
ESKO_Single_Ink_Control_Strip_Sepi1, i1iOA control strip for the Orange, Green, Violet and Blue inkx:\Esko\bg_prog_intellicurve_v1xx\dat\doc
Control strips for spot color printing
ESKO_Spot_Control_Strip_Sepi1, i1iO

x:\Esko\bg_prog_intellicurve_v1xx\dat\doc

a

Control strips not compatible with PressSync: Third party control strips can be measured but the layout must be described in an it8 file as described in the manual:
https://docs.esko.com/docs/en-us/curvepilot/18.1/userguide/home.html#en-us/common/cup/reference/re_cup_it8_striplayout.html

it8 files describing the layout of a control strips must be placed here: x:\Esko\bg_data_intellicurve_v181

Custom control strips: PressSync allows to measure a custom strip without the need to create an it8 file (see previous item > control strips not compatible with PressSync). Such a custom strip can be created with any application (such as PackEdge: use a Gradation or Standard strip SmartMark) but must have an i1 or i1iO compatible layout. Note that a custom strip must include ALL inks as defined in the curve set, so also spot colors if there are any added. Once the strip is created you will need to enter the values in the curve set:

  • Process Colors tab > Desired %Datarea on a Control Strip >> choose the number of patches and enter the value in the Tones row
  • Gray Balance tab > Desired Values on a Control Strip >> choose the number of patches and enter the value in the Tones row
  • Spot Colors tab > Desired SCTV on a Control Strip >> choose the number of patches and enter the value in the Tones row
Article information
Applies to

Curve Pilot

PressSync

Created

 

Last revised

 

AuthorSDOB
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