[Cin] "Competitors" or do we want to stay alive?

[Pekka Paalanen]

On Mon, 7 Apr 2025 14:44:25 +0300
Andrew Randrianasulu <randrianasulu at gmail.com> wrote:

> пн, 7 апр. 2025 г., 14:19 Pekka Paalanen <pekka.paalanen at haloniitty.fi>:
> 
> > On Fri, 4 Apr 2025 22:14:10 +0300
> > Andrew Randrianasulu <randrianasulu at gmail.com> wrote:
> >  
> > > пт, 4 апр. 2025 г., 21:35 Andrea paz <gamberucci.andrea at gmail.com>:
> > >  

...

> > > > A theoretical question: can CinGG be adapted to work in Wayland or is
> > > > it impossible? Has XWayland limitation?  
> >
> > X11 and Wayland designs for color management are fundamentally
> > incompatible.
> >
> > With X11, applications never tell the display server what kind of
> > pixels they are producing or which, if any, color profile they used for
> > the display. With Wayland, applications must describe their pixels to
> > the display server. Since X11 applications tell nothing to the X server,
> > Xwayland has no color information to forward to the Wayland compositor.
> >
> > There can be case-specific manual solutions, though, that rely on
> > correctly configuring both the X11 apps and the Wayland compositor. X11
> > apps need to be configured to render for a specific display profile,
> > and the Wayland compositor needs to assume the X11 windows are rendered
> > for the same specific display profile. How that is actually done is up
> > for each X11 app and each Wayland compositor.
> >  
> 
> Is there possibility for X extension for Xwayland allowing relatively
> simple way to tell Xwayland what to do with each window/region?

Hi,

sure, but would it not be more useful to invest that effort in a proper
Wayland integration?

X11 is fundamentally limited to max 32-bit pixels so its stuck at 30
bpc max with only 2 bits of alpha. That's probably the only thing that
cannot be worked around.

> A bit like
> 
> https://github.com/oyranos-cms/oyranos/blob/master/libxcm/include/X11/Xcm/Xcm.h

That's an interesting one, I wasn't aware of this. I have to take some
statements back.

So this is communicating ICC profiles and associated window regions to
an X11 compositing manager. If a profile covers the whole window, this
should be relatively easy to hook up in a Wayland compositor's XWM
(embedded X11 window manager).

Being limited to ICC profiles is a hindrance for HDR, although the CICP
extension for ICC does exist. Unfortunately CICP does not carry
everything we have in the Wayland color-management protocol extension.
Most notably, it misses the reference white level which would be
necessary[1].


Thanks,
pq

[1]: https://www.freelists.org/post/argyllcms/Standard-spec-for-ICC-file-that-can-be-used-for-HDR-calibration,1
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