[GSoC] KWin colour management

[Casian Andrei]

Hello,

I am a final year undergraduate student at the Polytechnic University
of Bucharest, Automation and Computers Faculty. I am interested in the
"Compositor Colour Management" idea from OpenSUSE. It looks like
something I would enjoy doing.

I have acceptable C / C ++ skills and lots of experience with OpenGL.
I am also familiar with Qt. Regarding shaders, I wrote a couple about
2 years ago for an old project, and I still know how they work, so it
would be easy for me to remember. Last GSoC I worked on an OpenGL
interface for VLC, and 2 years ago I worked on capture support in
Phonon.

I need your guidance in order to create a decent proposal. I
understand the project will involve implementing the colour management
features in KWin. As the idea suggests, this would imply making KWin
handle the _ICC_COLOR_OUTPUTS and _ICC_COLOR_PROFILES atoms.

Today I documented myself about colour management in general, and how
it's done in Linux. I also read about ICC, Oyranos, X color management
and related things. Now I'm not completely in the dark as before. I
looked around in the KWin code and I found the area of interest - the
compositor part, more specifically KWin::SceneOpenGL. Since shaders
will be needed, it looks like some custom shaders of type
KWin::ShaderManager::ColorShader would be able to do the job. Please
correct me if this is wrong.

But I am still unsure and I don't have an exact image in mind about
what needs to be done. Clearly, more exploration is needed. I don't
know what to concentrate on - looking around in KWin / Compiz code,
concentrating on libXcm and the X Color Management spec, reading more
about Oyranos and colour management in general?

I tried the Oyranos colour management LiveCD and I saw it doing the
correction magic, but unfortunately I was unable to get compiz working
- with the open source drivers it didn't start because of missing
glx_ext_texture_from_pixmap extension, and there were problems with
the ati drivers - after installing them, the root visual was not a GL
visual (or something like that), and if I tried to do some
configuration with Catalyst, then X froze together with the system
(nothing new for me, that's why I am sticking to the open source
drivers). At least I know ICC profiles for both my monitors were
found, by monitoring with QcmsEvents.

Best regards,
Casian