Control a grayscale

Checking the gray scale allows you to detect any drifts in your printers or to check the quality of a calibration.

Indeed, the grays, reproduced in RGB or CMYK mode, are not composed only of black, but are reproduced with all the inks of your printer. To obtain perfect neutrality, it is therefore necessary that the dosage of these inks be mastered. This should be the case if the printer is properly calibrated and stable.

The non-stability of a printer can be due to the following parameters:

• Equipment wear (print heads, pumps, etc.)

• Inks (expiration date, quality problem, etc.)

• Media

• icc profile (Profile not corresponding to the printing medium, etc ...)

• Calibration problem.

It is therefore advisable to regularly check your prints as part of a quality control in order to guarantee your customers the consistency and quality of your prints.

Creating an RGB Gray Reference

Click on the "Print Control" icon, then on the "Create reference" button and select the "RGB" mode.

Select the gray scale

Click on the button "Read my own Lab colors"

The first step is to check the neutrality of the gray scale that we are going to print.

Gray test pattern print

Click on the "Export" icon then select "Export to Tiff"

Save the range in Tiff or pdf format in a folder.

The test chart must be printed under the same conditions as a normal print to reflect the final result.

Gray scale measurement

When the range is printed, start the control measurement. Click on "Start measurement"

Position the spectrophotometer in its calibration position, then click on "Start calibration"

When the spectrophotometer is calibrated, measure the staff. The blue arrows show you the line to measure.

Record the reference measurement (optional step)

When the test chart is measured, you have the possibility to export the measurement of the range in order to view it in the Gamut Viewer for example. To do this, all you have to do is click on the "Export Reading" button and then select "Export table". Then select the folder to save your saved measurement in the .table format

As a reminder, the .table format can be used with modules: - Gamut Viewer - Color Table - Print Control

Viewing the reference measurement in the Gamut Viewer (optional step)

It may be interesting to display in 3D the result of the measurement of the gray scale to highlight any dominant

Import the previously saved .table file

Display it in the Gamut Viewer In the example below, we can see that the grays have a dominant tendency towards yellow.

Creation of the "Print Control" .pctrl file

Click on the "Reading done" button

In the information window, only the name of the setting is mandatory. All other information is optional.

When you have finished filling in the information, click on the "Save and Exit" button.

The Print Control file appears in the left column

Checking a grayscale against the values of the reference scale.

Comparing a gray scale against the values of a reference scale can be useful for: - Monitor the stability of your printer - Check the emulsion of your supports - Compare the calibration of your printer fleet - etc ...

You can now start measuring another gray scale to compare it to the reference gray scale values.

Select the "Print control" file in the left column, then right click to select the "Start control" option.

The range measurement procedure begins ... Make sure your spectrophotometer is connected, then click on "Start reading"

When the measurement of the three lines is finished, the new measurement is added to the list in the right column. Click on the "Reading done" button

The control report appears.

If you wish to measure other ranges, all you have to do is right-click on the Print Control file, then start the control. Each measure will accumulate with the previous ones.

To view the control report for each of the measurements recorded in the Print Control, all you have to do is click on the blue icon corresponding to the measurement concerned.

To erase a measurement

Click on the blue icon corresponding to the measurement you want to delete, then click on the trash can.

Be careful, by clicking on the trash can, you will no longer be able to retrieve the measurement.

3D comparison of a control measurement with the reference measurement

Click on the purple icon located in the "Reference" tab, then on the one located in the "Controls" tab. The measurement tables will appear in the left column.

Launch the Gamut Viewer interface to display in 3D the measurements of the previously measured ranges. To better discern the control measures, it is possible to assign a color. It is of course possible to display several measurements at the same time.

Saving the Print Control file

Do not forget to save your Print Control file if you wish to carry out regular checks on the stability of your printers. To do this, right-click on the Print Control file then select the "Export" option

Select the folder to save your Print Control .pctrl file

Once your .pctrl file has been saved, you just have to open it in Coraye to enrich it with new measures afterwards.