[Development] QT5 and color management

[Niels Ole Salscheider]

> I have looked into that previously. It is mainly blocked by uncertain scope,
> what color-spaces should be supported, and should they be tied to QImage,
> QScreen, QGuiApplicaiton, QColor or all of the above? I also postponed
> adding support for RGB64 QImage formats until I figured out how
> gamma-correction should be handled.
> 
> If we have a specific scope I can adjust my proto-type and suggest an
> implementation.

I started a discussion about colorspaces for qt5 back in 2011:
http://lists.qt-project.org/pipermail/qt5-feedback/2011-September/001298.html

One of the comments was that it would be good to see how color management 
could be done e.g. on wayland before deciding on how to implement it in Qt.
Therefore, I proposed a wayland protocol for color management and a weston 
implementation of it:
https://lists.freedesktop.org/archives/wayland-devel/2014-October/017759.html

In the end, it was considered to be out of scope for weston at that time but I 
think that the protocol is still sane. Having the implementation in weston 
does not really help as long as there is no toolkit that supports it. But I 
think that we could get the implementation into libweston nowadays if there 
was a toolkit that wants to use the protocol.

The most efficient way to use this protocol would be to ask the compositor for 
its blending space, render the window in this blending space (after converting 
all images to it) and then pass it to the compositor.

If someone wants to work on this for Qt, I would try to pick up the wayland 
side again.

Ole