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

[Mark Greenwood]

On Tuesday 22 Dec 2009 13:53:49 Martin (KDE) wrote:
> Am Dienstag, 22. Dezember 2009 schrieb Mark Greenwood:
> > On Tuesday 22 Dec 2009 09:16:41 Martin (KDE) wrote:
> > > Am Dienstag, 22. Dezember 2009 schrieb Guenther Erhard:
> > > > > > I cannot find anywhere in system settings that allows me to
> > > > > > select a profile. Nor can I find any reference to it in
> > > > > > Google or by searching the KDE site.
> > > > >
> > > > > So may be it has something to do with this:
> > > > > http://www.argyllcms.com/doc/dispwin.html#I
> > > > >
> > > > > It seems to go the same way as gimp and ufraw do it already.
> > > > > A dialog to query currently set display profile would be fine
> > > > > anyway.
> > > >
> > > > Yes, that is possible, but "set | grep ICC" does not show any
> > > > set environment variable.
> > >
> > > The data is not stored in environment variables but as property
> > > in X11. For the dispwin tool the configuration is set in
> > > ~/.config/color.jcnf. My data is set as:
> > >
> > >   "devices": {
> > >     "display": {
> > >       "1": {
> > >         "EDID":
> > > "0x00FFFFFFFFFFFF0015C37916010101010C0E0102681E1778EAA415A5544897
> > >250F5054BFEE000101010101010101010101010101010164190040410026301888
> > >360030E410000018000000FF004B353134333033340A20202020000000FD00374C
> > >183D08000A202020202020000000FC004C3336370A20202020202020200022",
> > > "ICC_PROFILE":
> > > "/home/blablub/.local/share/color/icc/devices/display/eizo.icc"
> > >       },
> > >       "2": {
> > >         "NAME": ":0.0",
> > >         "ICC_PROFILE":
> > > "/home/blablub/.local/share/color/icc/devices/display/dell-L.icc"
> > >       }
> > >     }
> > >   }
> > >
> > > If I load color profile (dispwin -L) the one for my current
> > > display is loaded (here dell-L.icc) the eizo.icc I used with my
> > > old monitor.
> > >
> > > > In my case I don't use dispwin - I use xcalib to load the
> > > >  calibration profile at every startup of X11.
> > >
> > > I don't know xcalib, but it must do something similar.
> > 
> > Now I'm even more confused. I have never heard of xcalib or
> >  dispwin.
> > 
> > I have a monitor profile for my monitor and I want Digikam to use
> >  it. What is all this config files and load at startup of X11
> >  nonsense?
> 
> 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.

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. 

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?

Mark

> 
> So If you want to use your Monitor profile reset all your monitor 
> settings to default. Install argyllcms (or xcalib) and load the icc 
> file at login (first time: dispwin -I /path/to/display.icc; next: 
> dispwin -L). Next you have to load the file as display profile in your 
> application.
> 
> Be aware: colour management does not improve the colour itself.
> 
> Next important step is to choose a working profile. Here you are free 
> to choose every profile you want, but without a hardware calibrated 
> monitor best use may be sRGB. AdobeRGB does not bring you more colour 
> if your Monitor is not able to show it (which most monitors can not). 
> Even worse: If you use 8-bit encoded RGB you loose some fine 
> granularity in the less saturated part of the image.
> 
> Conclusio: If you want to use 8-Bit RGB use sRGB (you avoid problems 
> if you print images or give them to others). If you want higher colour 
> range use L*-RGB and 16-Bit. But then you have to buy a hardware 
> colorimeter and a monitor which can display this colours reliably. 
> This will you cost you at least 1000 Euro for the monitor and 250 Euro 
> for the colorimeter.
> 
> Martin
> 
> > 
> > Mark
> > 
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