[RFC wayland-protocols] Color management protocol

[Pekka Paalanen]

On Wed, 21 Dec 2016 10:30:50 +0000
Richard Hughes <hughsient at gmail.com> wrote:

> On 21 December 2016 at 09:14, Pekka Paalanen <ppaalanen at gmail.com> wrote:
> > I suggest that compositors use the CMS you have spent so much time and
> > effort perfecting, and you start with the assumption that they will not
> > or cannot do so. Why?  
> 
> I think lcms2 is fine to use; it's widely used in other projects,
> tested, and already optionally used in weston.
> 
> > Are you implying that the CMS you worked on so hard is impossible to use
> > from a compositor?  
> 
> I think that's basically correct, argyllcms doesn't have any header
> files or shared libraries. When using it to generate color profiles
> for things like printers from gnome-color-manager I have to spawn the
> binaries themselves (and only in a VT...) and then scrape the output.
> https://git.gnome.org/browse/gnome-color-manager/tree/src/gcm-calibrate-argyll.c#n273

Oh, that's a huge surprise to me, being accustomed to open source.

> > Yes! The CMS needs to provide the API that all compositors could use.  
> 
> I'm not a great fan of pluggable CMSs, it's a bit like designing a car
> that has a requirement that the engine is swappable with another
> whilst driving down the motorway. I'm a great fan at pointing people
> to http://www.islinuxaboutchoice.com/ when they ask about things like
> this.

Sorry about the typo, I meant "an API", not "the API". We're not
Khronos, indeed.

Just like programs can choose their toolkits, compositors should be
able to choose their color management providers for calibration and
color processing. We would still have the public and generic Wayland
extension for providing color-managed content, so it would not affect
normal application compatibility.


Thanks,
pq
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