Some color management in ubuntu linux
I’m discovered a few days ago that eye of gnome (eog) in the ubuntu 7.10 release picks up the color profile if it’s set with the xicc tool. Eog also read embedded color profiles from jpg images.
I tested this on a laptop. The xicc are place in the universe repository, and can be installed with sudo apt-get install xicc. Other tools that support this feature are listed here.
Here is some sample screenshot.
This is my desktop after just loading 3 images. One of the images is in srgb space, the other in pro photo rgb and the third in adobe rgb. On my monitor there is a quite big difference between this situation and the next, but I have loosed the differences in the screen capturing process. I have taken a photo with my camera that shows the difference much better. You find it longer down on this page.
The same situation after loading the lut. It is done with “dispwin ~/.color/icc/ferrari.icc”. As you hopefully see, the srgb image looks much better no, because the color are now more linear. I guess this is what people call a calibrated display.
Full size
The situation after also loading the xatom with xicc, and reloading the images. It is done with “xicc ~/.color/icc/ferrari.icc”
All images are now displayed correctly with eog . This is a calibrated and profiled display with linux. If you notice it also the srgb image(the left one) have improved in color on the last screenshoot. The screenshoots are actually converted from my monitor profile to srgb. So they have a better match than an ordinary screenshoot.
It was quit hard to show the difference between all this stages with screen grabbing. So I found my camera. I metered the color temperature with my spectrophotometer and dialed in the kelvin degress on the camera. The output should now visualize each step much better.
There is some bugs with the screensaver resetting lut and so on. You also have to type the command each time you boot. A simple solution is to create a small shell script and place it in the panel, and click on it when you are in doubt. 
Next version of dispwin will also have an option for loading the xatom. (Thanks Graeme, the author of Argyllcms). Then it can be done with one tool, but until then use dispwin and xicc, or try oyranos.. Update Graeme Gill announced beta8 the day after I write this blogpage. The profile loading can now be done with:
$dispwin -S ~/.color/icc/Ferrair.icc #load the X11 atom
$dispwin -L # loads the lut
and can be cheked with
$dispwin -V ~/.color/icc/Ferrair.icc #verifyes the installed video lut
$xprop -root|grep ICC # check if the xatom is et. (it’s output the _ICC_PROFILE blob, just numbers)
With new beta8 argyllcms a calibartion and simple profiling of a laptop can be so simpe as
$dispcal -v -m -y l -o laptop
You can event try this with an lcd, just remember to reset the monitor to factory defaults before you type the command. It is necessary if you have messed with the so called color controls. With the above command you don’t have to adjust anything and you end up with a profle in your working dir. Try sudo before the command if have problems. This creates a shaper/matrix profile. On my low-end monitors I end up with a much better profile with the standard route with dispcal,targen and dispread.
You may load the profile as described above. In some programs like cinepaint and bibblepro you still have to choose the profile manually.
Update end
I think it’s time now to pick up a colormeter, if you don’t have one already. The great news is that argyllcms now supports cheap colormerers, like the huey
The two kids in the image above are mine. This image are of course also obsolete in a few weeks?, when the next kid enter this world.