A solution for gamma-adjustment support in Wayland

[Kai-Uwe]

> Date: Wed, 7 Dec 2016 13:10:52 +0100
> From: Mattias Andrée <maandree at member.fsf.org>

> ### Abstract ###
>
> With the advent of Wayland, our display server has lost a functionality
> — access to the graphic cards’ colour loop-up tables — that has been
> used to implement, amongst other things, ergonomic functionality. But
> we now have a chance to start from scratch and do it the right way.

The assumption of a out of band color communication is not convenient
nor relyable. So colord for ICC stuff in wayland is the bad as is
currently state. Each window system should support proper gamma ramp
access and a way to transport ICC profiles along the logical monitor
connection APIs. So far all color relevant display systems have evolved
like this sooner or later.

libcoopgamma is GPL. A really unacceptable choice for a API, which shall
be used by everyone to reach the goal of a more structured / disciplined
gamma access.

Color correction goes recently more and more into the CLUT direction.
That is different to the per channel gamma APIs you propagate. An
abstraction of gamma versus CLUT is needed. Effects should not be
sticked to a particular technology or they will fail in many cases: e.g.
the need to reinvent this API if one needs a desaturated appearance.

best regards
Kai-Uwe