Device colour profiles - on / off button not working Ubuntu 18.04.3LTS

[Martin Kyle]

I've been trying to calibrate my printer in Ubuntu 18.04.3LTS with gnome-control-center:
  Installed: 1:3.28.2-0ubuntu0.18.04.5
  Candidate: 1:3.28.2-0ubuntu0.18.04.5
  Version table:
 *** 1:3.28.2-0ubuntu0.18.04.5 500

The least documented part of printer profiling is printing the target. Every guide says turn off printer profile calibration, but no-one tells you how.
Through trial, error and a lot of paper and ink it seems to me as though the on / off button next to the printer description does nothing.
If the user deletes all existing profiles the field reads Not calibrated and no button is displayed, though on a reboot this changes to a button showing colour management (CMS) on and two default profiles are displayed (default RGB and default grey) with RGB selected. The output of these two states is identical. If the setting is default RGB profile with no others loaded, then changing Cups in a browser to Colour Correction: uncorrected refreshes the state to Not Calibrated, though this is the only time I could force this. Setting Cups to Colour Correction: high accuracy does result in an altered output from the printer. I am guessing this is no colour profiling being applied.
However if Cups Colour Correction: uncorrected is set, and a profile is loaded in Device Colour Profiles the output from the printer is the same whether or not the CMS on /off button is pressed. I think this is the result of the profile applied by Device Colour Profiles in either case.
Similarly, using Cups Colour Correction: High Accuracy and a profile loaded in Device Colour Profiles, the printer output is the same whether or not the CMS on /off button is pressed, though the output is different from the preceding example. I presume this is the result of two colour transformations being carried out.
The attached images of my printer output should hopefully help explain this situation.

[Sebastien Bacher (seb128)]

Thank you for your bug report.

Till, could you have a look to what is described there and try to summarize the issue/advice of what we could change?

[Till Kamppeter (till-kamppeter)]

To turn off color management on a CUPS print job you have to turn on calibration mode. On the command line it is done as follows:

lp -d printer -o cm-calibration=1 file

The option has the possible values 0 and 1.

The button mentioned should probably add this option to the print job, or when it is not in the context of printing a job but managing a print queue it should set the default of this option on the print queue. The option is available for all printers (provided by cups-filters).

[Martin Kyle (dm-kyle)]

Ok, so I was looking for an option like that but could not find it in any documentation. Just to add I was printing .ps targets from Argyll's targen / printarg / chartread / colprof workflow with:

lp target.ps

I did some more test prints and have attached the results again.

The -o cm-calibration=1 option does seem to turn off calibration from "Device Colour Profiles" but the "color correction setting" in CUPS still has an effect on print output, quite noticeable on a couple of targets which go from orange to purple.

I am going to create two profiles from targets printed with the -o cm-calibration=1 option with:

  a). Device Colour Profiles cms ON and a profile loaded, but Cups colour correction set to High Accuracy.

  b). Device Colour Profiles cms ON and a profile loaded, but Cups colour correction set to Uncorrected.

Hopefully I will then be able to asses the best way forward.