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

[Mark Greenwood]

On Tuesday 22 Dec 2009 14:56:20 Martin (KDE) wrote:
> 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.

OK thanks, I understand that now.

> 
> > 
> > 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

This is one reason why I say it's hard. It's very non-obvious to someone like me how I get a script to run every time I log in. Also how am I supposed to know that I need this application called 'argyllcms'? It's not something you average user ever wants to take an interest in, or should need to know about - colour management is complex enough without having half the answer made up of random extra bits of software. From what I can see here there's a lot of work still to do to get Colour Management working usefully on Linux. I think I will just disable it for now.

Mark

> 
> 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
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