[clug] Colour management

[Scott Ferguson]

On 06/01/17 09:56, Sam Parkinson wrote:
> On Fri, 2017-01-06 at 03:11 +1100, Bryan Kilgallin wrote:
>> My PC runs Ubuntu 12.04 LTS. Its monitor is a Lenovo ThinkVision
>> L192p 19".
>>
>> I had thought the display a bit pink for my liking. So I want to 
>> recalibrate that.
>>
>> The Screen Display window has detected a Lenovo Group Limited 20"
>> display.
>>
>> And the Device Colour Profiles window lists Lenovo Group Limited -
>> LEN 
>> L192p. Under "Calibration", is greyed-out "Uncalibrated".
> 
> I think the calibration needs a special calibration device.

Spyder4, Pantone and other (ColorHug?) will do that - perhaps someone on
the list has one?

In most cases the simplest solution is to use a pre-existing ICC
profile. You can sometimes download one from the monitor manufacturers
website, extract it from a driver, or just copy it from Windows - if you
have Windows installed and it has a profile for that specific monitor.
Lenovo displays normally provide Windows drivers (there are Linux tools
that will allow you to extract the ICC profile - see
http://www.thinkwiki.org/wiki/Colour_profile).

Typically the Windows ICC profile is in
C:\WINDOWS\System32\spool\drivers\color - note that it's a binary file.
Apple also uses the same profiles (but I forget where they keep them).
Debian keeps manufacturer ICC profiles in /usr/share/color/icc

If you have an ICC profile you can import it and use it under Linux
using gcm-import (GNOME)

For KDE Oyranos provides tools for color-managing a workspace
http://www.oyranos.org/downloads/ (KolorManager is the frontend).

If you want to create an ICC profile take a read of the Argyl
documentation http://www.argyllcms.com/doc/ArgyllDoc.html
The Linux front-end is dispcalgui (in Debian). GNOME uses
gnome-color-manager - also see "man colormgr" and "man gcm-calibrate"
(also "man gcm-import").
LPROF lprof.sourceforge.net also creates ICC profiles (it's a gui
version of lcms* with a few more features).


>  Maybe
> GNOME greys out the button if you do not have a compatible device.

>From memory it looks for a line (Device ID?) in xrandr output. If you
create one (xorg.conf.d) you should then be able to create a profile
with gcm-calibrate


> There is a "how do I calibrate my screen" section in GNOME Help, part
> of the "color management" book.
> 
> Thanks,
> Sam
> 
> --
> 
> latest blog post:  https://learntemail.sam.today/blog/my-watch-runs-gnu
> -linux-and-it-is-amazing/
> 
>>
>> More detail is provided for this LEN L192p device. But under 
>> "Calibration", "Not specified" is greyed-out. And the "Calibrate"
>> button 
>> is also greyed-out. Information for this LEN L192p device lists the 
>> Filename "edid-3104471e3020a08ad8fed175ab380a3b.icc". Which 
>> unfortunately I could not find by searching either the File System
>> or 
>> the Web!

That's an ICC profile generated by edid - it often unreliable
try:-
ls ~/.local/share/icc/edid-*.icc

if it's not there try:-
(as root) updatedb;locate .icc | grep .icc$



Kind regards