[patches] Add a color management framework to weston

[Graeme Gill]

Bill Spitzak wrote:

> Maybe the client should be able to query the color space of the output
> and can set the color space of it's buffer to the same one, this would
> indicate that no color correction is needed. The compositor could still
> color-correct it from one output's color space to another's if it is on
> multiple outputs.

This is not as simple to set and as safe as an explicit opt out.
(Apple has had a lot of trouble as a result of doing their
color management opt out this way). It's hard to confirm that you've got
the same profile ("same" in what sense ? Same instance of the profile ?
Same bits ? Same notional colorspace ?)
You would need a special case anyway to implement a null transform,
because things like cLUT profiles have A2B and B2A tables that are not
perfect inverses.

You'd also want to be sure that a null transform is bit perfect, and
that something isn't lost in shaders etc.

If this idea is still attractve, I would suggest supporting device links,
making it reasonably simple to set a null device link.

> Ideally a client should be able to do this with just some strings (ie
> query the color space and send the same string as the buffer's color
> space) so it does not have to open a CMS library that it might otherwise
> not be using.

If that's the case, I'd suggest having a string that turns the color management
off. Much simpler and more direct as to the intention.

Graeme Gill.