HDR support in Wayland/Weston

[Graeme Gill]

Chris Murphy wrote:

> A common offender were games. They'd try to access the video card LUT
> directly for effects, but then not reset it back to what it was,
> rather reset it to a hardwired assumption the game makes,

And the current favorite is "blue light filter" effects, for which numerous
applications are currently available. They tweak the white point
of the display by arbitrarily modifying the hardware per channel LUTs.
(i.e. f.lux, Redshift, SunsetScreen, Iris, Night Shift, Twilight etc.)

Such applications have their place for those who like the effect, but
ideally such usage would not simply blow color management away.

In order of desirability it would be nice to:

3) Have the hardware Luts restored after an application that uses them
   exits (i.e. like OS X handles it).

2) Implement virtual per channel LUTs, with the compositor combining them
   together in some way, and have some means of the color management applications
   being aware when the display is being interfered with by another application,
   so that the user can be warned that the color management state is invalid.

1) A color managed API that lets an application shift the display white point
   using chromatic adaptation, so that such blue light filter applications
   can operate more predictably, as well as some means of the color management
   applications being aware of when this is happening.

Cheers,
	Graeme Gill.