Public bug reported:

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.

** Affects: gnome-control-center (Ubuntu)
     Importance: Undecided
         Status: New

** Attachment added: "A series of jpgs showing the process"
   
https://bugs.launchpad.net/bugs/1855615/+attachment/5310861/+files/printer%20output%20pictures.zip

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https://bugs.launchpad.net/bugs/1855615

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

Status in gnome-control-center package in Ubuntu:
  New

Bug description:
  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.

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