> Last year, I managed to profile my Samsung 226CW monitor using an
> Eye-One LT under Fedora 7 and the argylcms programs.   When I told gimp
> what the display profile was, the results looked plausible.  At that
> time I was using an early version of gimp 2.4.
> But my monitor dimmed somewhat, and I wanted to redo the
> calibration/profiling.   But it doesn't seem to be working.   I also
> tried the same thing with a laptop running Ubuntu 8.04, and had similar
> problems.   
> The process produces a calibration (look up table) which is loaded into
> the video card and also a profile which a program such as gimp can  use
> to tell the display how to interpret colors.  There are two ways to tell
> gimp about the display profile, but it doesn't seem to matter which I
> use.  What happens on both machines is that gimp seems to be negating
> the calibration (look up table) in the video card and then perhaps
> applying some profiling to the result.  So what I get with a gray scale
> is the whatever tint the screen had without the look up table loaded;
> red-magenta for the Fedora machine and blue-cyan for the laptop display.
> So either I keep doing something entirely idiotic, or gimp color
> management is doing the wrong thing.  The versions of gimp I've been
> having this problem with are 2.4% and up.  My current Fedora version is
> 2.6.3.
> Supposedly Eye of Gnome can also use a display profile, and it in fact
> it doesn't show such an effect. The gray scales look plausible, but they
> might anyway, just with the calibration loaded in the video card and no
> profiling. But, if Eye of Gnome allows for color management, I would
> expect it to say something about it and possibly allow some
> configuration, and I can't see any indication that it is doing that.
> Is there some other method independent of gimp to check whether the
> profiling is working?

I've since discovered that inkscape also has color management.
It behaves the same way, so the problem is not specifically a gimp
problem.  It could be a problem with lcms, argyllcms, my measurement devices 
(although it seems unlikely they are both failing the same way), or the way
I am going about making the profiles.  With respect to the latter, I've
tried a variety of approaches, and the phenomena occur both with my
Smasung226W on a Fedora desktop and an Ubuntu laptop using its screen.

As I noted above, the problem seems to be that the profile is
overcorrecting the calibration lut loaded in the video card, thus moving
colors back towards the uncalibrated monitor.  And that means a red-magenta
tint for one machine and a blue-cyan tint for the other.

> Any suggestions would be appreciated.
Leonard Evens <l...@math.northwestern.edu>
Mathematics Department, Northwestern University

Gimp-user mailing list

Reply via email to