Background

You can use print calibration curves to align a curve-controlled device to an industry specification. A print calibration curve can make the printed results of a halftone output device match either the tonal response or gray balance of a target device condition.

This activity creates a print calibration curve to align a press with an industry specification for tonal match. Tonal match refers to the Tone Value Increase (TVI), also known as dot gain, of the target specification and uses the calculated Effective Dot Area (EDA) for calibration. EDA calculations are based on the density measurements of each ink or colorant.

When using a ColorFlow curve for tonal calibration in Prinergy, you can make instant on-the-fly adjustments for dot gain directly in Prinergy Workshop at the time of output, without having to return to ColorFlow to make any adjustments.

Tasks

Goal
Create a print calibration curve with a defined industry tonal match specification. After the curve is created, use the print curve to output a job in Prinergy and make an on-the-fly tonal adjustment to compensate for an unexpected press fluctuation.

Task 1: Create a print calibration curve to match an industry specification 

  1. In ColorFlow, click the Print Curves tab.
  2. In the Calibration Curves section at the top-left, click the Add button .
  3. In the Devices dialog box, add a new device : 
    1. In the Device Name box, enter XX Offset Press (where XX = your initials).
    2. From the Device Type list, choose Offset Press - Sheetfed.
    3. Click Create.
    4. Drag the device you just created to the viewer window and close the Devices dialog.
  4. Click the Properties icon  on the press icon.
  5. From the Plate Setup list, select None. You can also select a plate setup defined in the Plate Curves tab.
  6. From the Screening list, select  20u Staccato  or add the value to the list if it doesn't exist. Skip this step if you selected a plate setup above.
  7. From the Substrate list, choose Type 1 or 2 (coated art) 170 g/m2.
  8. Leave Process Inks and Other with the default values.
  9. Click OK.
  10. Create a Tint Ramp chart:
    1. Click the Measurement icon  in the Offset Press panel.
    2. In the Charts section, click the Add button .
      A chart appears in the Charts list with a default name.
    3. From the Chart Type list, choose Tint Ramp. 
    4. In the Tint Set section, click the Edit button .
    5. Click the Add button   and enter 0 10 25 50 75 90 100.
    6. Click OK.
    7. From the Process Ink Set list, choose CMYK.
    8. Click Save. You can change the default name of the chart to CMYK_Tint_Ramp
  11. Enter the measurement values. In a real-life situation, you would print the chart and measure the chart using a measurement device. For the purpose of this training, you will enter the given EDA values:
    1. Disconnect any measurement device and then click Measure.
    2. In the Characterization Print Curve dialog, keep the default value  Linear (None) and click OK.
    3. In the Connection Error dialog, click Enter Manually.
    4. Leave the Tonal Response Metric: as Murray-Davies Effective Dot Area
    5. In the Channel Binding section at the bottom-left side, click C, M, Y, K Same

    6. In the Tonal Response section at the to- left side, enter the following EDA values:

      Tint inEDA
      1012
      2529
      5057
      7582
      9093

    7. Click the OK button on the bottom-right side.

  12. To review the measurement value:
    1. Click the Measurements tab.
    2. Select the chart and click View.
    3. Select the Show Measurements check box.
      You will be able to view and edit measurement values in the Tonal Response section. 

    4. Hit Cancel at the bottom right to close the Tonal Response panel, then hit the X button at the top right to put away the Device Measurements panel.

  13. Define the calibration target as an industry specification:
    1. Click the Calibration icon  in the link area between the Calibration Target and Device Condition panels.
    2. Ensure the Show curves in Prinergy check box is selected under the Conversion Name.
    3. Click the Process Inks tab and choose GRACoL 2006 Coated 1 from the Target list.
    4. Do not change Curves Method: Tonal Match, which is automatically selected
  14. Click OK.
    A print calibration curve is generated to match the tonality of the chosen industry standard. 
  15. In the Calibration Curves table list at the top left, find the curve, double-click to select the default curve name and enter XX New print calibration curve for tonal match (where XX = your initials). Click anywhere in the blank area to set the curve name.

Task 2: Output a job using the newly created print calibration curve

  1. In Prinergy, create a new job, and name it as XX tonal match (where XX = your initials).
  2. Refine CMYK_Tint_Ramp.pdf with 1stRef-Normz.
  3. Output the PDF file using Virtual Proof.LoosePage with the print curve you just created:
    1. In your Virtual Proof.LoosePage Process template dialog box, from the Output To list, choose Virtual Proof.
    2. Leave ColorFlow Color Relationship Management unchecked.
    3. Expand the Calibration & Screening panel.
    4. Click the ColorFlow Current State radio button.
    5. Expand the Print Curve drop down list and select curve XX new print calibration curve for tonal match .
  4. Open the generated page in VPS and measure the 10%, 25%, 50%, 75%, and 90% Black patches. 
    Confirm that the plate calibration curve has been applied: Black 10% measures 15.7; 25% measures 36.1; 50% measures 62.0; 75% measures 84.4; 90% measures 95.7.

Task 3: Make an on-the-fly tonal adjustment in Prinergy 

  1. In Prinergy, start a final output process using the same process template used in Task 2.
  2. In the Start Process dialog box, click Tonal Control... 
    The Tonal Control dialog box appears showing the information from the separations in the surfaces of the job selected for output.
  3. From the Separation list, select Black.
  4. The Curve Channel list displays the ColorFlow curve channel that has been assigned for the selected separation. From the Curve Channel list, choose Black.
  5. To make tonal adjustments, in the Tonal Adjustments section, drag the sliders or enter the desired values directly into the boxes under the sliders. The  Midtone (50%)  control affects the full tonal range. If you adjust the Midtone (50%), the Quartertone (25%), the 3/4 Tone (75%), the Highlight (10%), and the Shadow (90%) are adjusted according to the value of the Midtone (50%).  For the purpose of this training, in the box under the Midtone (50%)  slider, enter  -5 .
  6. Click OK.
  7. After the output is done, open the generated page in VPS and measure the 10%, 25%, 50%, 75%, and 90% Black patches.
    Confirm that the tonal adjustments you made are applied: Black 10% measures 14.2; 25% measures 32.7; 50% measures 57.0; 75% measures 80.9; 90% measures 94.2.

Outcome

You have created a print calibration curve for tonal match to an industry standard and made an on-the-fly tonal adjustment in Prinergy.

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