[Digikam-users] suddenly cannot choose a monitor profile in settings

[Martin (KDE)]

Am Dienstag, 22. Dezember 2009 schrieb Mark Greenwood:

> > Sorry Mark, this is no nonsens. for a colour managed environment
> > you have to calibrate and profile your monitor. Usually this
> > results in a icc or icm file.
> >
> > The calibration stuff is loaded usually at login time. This sets
> > your Gamma curve (and colour temperature) to what you have set up
> > your icc profile to (I have a L-Star gamma and a colour
> > temperature of about 6500K - my native display colour).
> >
> > The profile stuff is done by the application (digiKam, Gimp or
> > UFRaw). So you have to either set it manually in every
> > application or you can use the system wide profile (which is the
> > one you loaded at login). This makes sure that red in sRBG is
> > displayed ecactly as the same red as in AdobeRGB or eciRGB (as
> > long as they are in the available range - called Gamut).
> 
> Thanks for replying - I understand colour managemnt (or I thought I
>  did) and I have an icc colour profile for my monitor. What I don't
>  get is why I need to load it twice - once at startup and then
>  again in Digikam. Logically and intuitively this implies to me
>  that I am now getting the colour adjustments twice - once by the
>  system once by Digikam - and that therefore the colours displayed
>  will be wrong.

It is not done twice. The first part fixes gamma, colour temp and 
light (if set). It is done for all application using this monitor. No 
colour adjustment is done at this stage. As your monitor is hardware 
calibrated to sRGB this part may not be necessary but will nor harm.

The second part (done by the application) fixes colours only.

> 
> My monitor gamma and colour temperature is already factory
>  calibrated to sRGB. What I used to do was simply select my working
>  colour space (wide gamut) and my monitor colour space (sRGB) in
>  digikam. Now I cannot do this.
> 
> This stuff is FAR too complicated. I had it working for me but now
>  a software change has stopped that from working.

This seems to be a bug. You can go around this by loading the default 
profile with dispwin and use the system default profile. (I can not 
check this, as I am currently stuck to digiKam 0.9).

> 
> On a Mac I choose 2 profiles in the system settings and it's all
>  done. On Linux it appears I need to be able to write a thesis on
>  colour management. Why does it need to be so hard?

It is not as easy as for a Mac but not that hard either. As I said 
before, you need three steps:
- Install argyllcms
- at first time run dispwin -I /path/to/profile.icc
- at every login run dispwin -L

I have a script in /etc/kde/env called lcms.sh which runs dispwin -L 
at every login and I am done. Gimp and UFRaw uses this profile 
automatically. The main advantage: If I am on my second computer with 
my old Eizo monitor I don't have to change anything (home directory is 
on a NFS Server so I have the same settings on every host I log in).

> 
> Mark
> 

Martin