[RFC wayland-protocols v2 0/1] Color Management Protocol

[Erwin Burema]

Thu Mar 7 08:37:11 UTC 2019 Kai-Uwe
> Am 06.03.19 um 18:09 schrieb Sebastian Wick:
> ...
>> Which brings me to open issues:
>>
>> 1. Does it make sense to support device link profiles? I'm against it
>>    but would love to hear if anyone has objections given that they are
>>    supported in the other proposal.
> pro device link:
> * GPU color conversion for pro applications (print/theater proofing)
> * handy for caching
> * application decided look for arbitrary outputs from one surface
> (currently not possible in X11)
> * a surface can be mapped virtually anywhere without the client to know

Cons of device link
* Compositors would need to support every color space ICC profiles
support (otherwise the advantage for pro application disappears),
which is problematic since ICC supports up to 15 channels
(theoretically don't think many things go above 4 to 6 or so, CMYK
probably the biggest), patch/spot based (think Pantone)
* Even when mapping to arbitrary outputs only one of those can
actually be accurate since that will be the one with the device link
profile
* Caching won't really be that effective since every app will probably
use their own device link profile anyway

All in all I would say that the trouble is not worth it so long as the
pro-application can get the output profile (which is needed to create
a device link profile anyway) any mapping to other screens can be done
with an output to output transform, which albeit not accurate should
be good enough. Device link profiles are most useful for when
something doesn't support color management and you need to do it
externally (probably in a batch), for example certain printers,
desktop backgrounds, etc.

Kind regards,

Erwin Burema