Xorg/Gnome color profiles

3Dade` • 27th Apr 2007 • Italian

I had Ubuntu and OSX in dualboot for a long time. One of the reasons I always loved OSX is the way everything looks so cool. Finally I’ve been able to understand what is (was) the difference. Osx has a superior management of color profiles.
Each video device (both for acquisition or reproduction) has it’s own ICC profile. This means that before any content is displayed, it is modified according to the device profile.. I used the same background image on both OSes and here you can see the difference :

Ubuntu/Gnome

Mac OSX

So I surfed the web to find about ICC support on xorg. The only tool I found is called “xicc” by Ross Burton: he made a spec and modified eog (eye of gnome) to use the profile loaded by xicc. I tried to load the “Color LCD.icc” I took from osx .. and guess what ?

Here you can see the image in the background “badly” displayed by default, and the corrected one (inside eog).. colors are just like in OSX.
Sadly at the moment the only app that supports the xicc spec is eog..

so I adopted a quick trick. Ross told me that the profile provided by apple should be only a gamma ramp correction and I could achieve the same result using “xgamma”, setting the same gamma values that the profile modifies. I was not able to find a tool to extrac RGB gamma values from ICC profile, but I did some guesswork.. and came up with this :

xgamma -rgamma 0.7 -ggamma 0.67 -bgamma 0.6

I suggest to try these settings for everyone that’s using an Apple LCD. The result is pretty cool, it gives more contrast, more color saturation.
And if you don’t like it you can revert to default typing :

xgamma -gamma 1.0

I hope that Xorg and Gnome will have xicc full support soon. In the meantime I’m quite happy with this trick.

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