[RFC wayland-protocols] Color management protocol

[Graeme Gill]

Daniel Stone wrote:

Hi,

> I'm going to be very blunt here, because the attitude, arrogance, lack
> of respect and civility, and general unwillingness to see a point
> demonstrated by multiple people in this thread is perhaps the worst
> I've ever seen on this list.

I'll agree with that. It's certainly disconcerting to
have serious subjects that are the result of a lot of experience
and thought rejected out of hand without much apparent effort
to understand what's behind them.

> I recommend you re-read Pekka's emails a couple of times until they
> sink in. It is clear that you are extremely experienced in colour
> management;

I think that applies in the other direction as well.

> more so than most in this discussion. It is equally clear
> that you do not understand Wayland as a system, its fundamental design
> principles, nor the things modern desktops do to invalidate pretty
> much every single assumption that your arguments are resting on.

That's almost certainly true, in spite of any effort that I've
made to get up to speed on the subject.

> If you reduce Wayland's capabilities to that of X11, then some of
> your suggestions may be less wildly unsuitable, but on the other hand,
> we might as well be using X11 if that were the case.

It's not my intent to do so, but to contrast the gap in
capabilities that currently exists, and would like
to see filled in a workman like manner.

> Let's say that the target here is a user for whom absolute colour
> correctness is so critical, that they have deeply specialised
> applications and hardware, monitors most people have never heard of,
> secondary measurement and calibration hardware, and have sunk a great
> deal of time into specifically configuring this.
> For such a user to pick a compositor which was actively bad at colour
> management would be rank stupidity.
> 
> If you don't trust the compositor you're using to do the thing which
> is above all else most important to you, maybe pick something else?

If there is no capability or standardization in this area for Wayland based
systems, I don't see how such a user has any other choice than to pick a
"compositor" called Microsoft Windows or Apple OS X. That would be a shame.

> I appreciate parts of this thread have been frustrating, but the fact
> you're participating in these discussions whilst slating Wayland as
> poorly-designed crap that will never take off,

At no stage have I said anything of the kind!

Computer graphics has been of core interest the whole
of my professional life, and believe me, I have an
appreciation of what's involved in creating a system
like Wayland.

But I'd like to see it step up a notch and be a color management
aware/capable system, so that it is a complete foundation for
the future.

> suggests that a) you
> don't actually understand it (objectively true, by this thread), or b)
> deliberately saying these kinds of things to get a rise out of people.

No, I'm trying to get them to see the bigger picture, and
get them thinking about approaches to solving the problems presented,
rather than focusing narrowly on Wayland.

>> So the future is pretty clear - if Wayland doesn't accommodate
>> color management, then no applications or users of color
>> applications are ever going to use Wayland. No
>> Scribus, Krita, GIMP, Inkscape or Darktable for Wayland.
>> No Photographers, Videographers or Desktop publishers using
>> Wayland.
> 
> This is risible hyperbole, and total rubbish.

I am trying to get some minds focused - yes.
(And maybe I'm failing badly in that effort,
 and letting my frustration show too much.)

But I am totally serious. If Wayland's color management
ends up technically second rate, then there is ample
reason to recommend that people working in areas
that benefit from good color management steer clear
of it. That's not a pleasing prospect when it might
be avoided.

> You're painting a false dichotomy where either people use external
> tools to allow colour-critical users to compensate for the damage
> their known-bad compositors do, or there is no chance of ever having
> colour management ever. If only there was a third option.

I'm not sure what you mean by a "known-bad compositors",
nor do I really understand how this paints a false dichotomy.

The external tools are a means of creating the data to
allow for managing and compensating for their particular displays.
A competent application to create this data is non-trivial.
If a graphical systems makes implementation of such software
difficult or awkward or laborious, then such software
may be slow to be developed for such systems. Without
these tools then either color management can't exist
on those systems, or it is compromised (i.e. using EDID
derived profiles, or stock profiles), or awkward workarounds
are needed (switch to an X11 server, boot Windows etc.)

> This thread perhaps demonstrates why many projects which would
> otherwise care about colour management have such difficulty supporting
> colour management correctly.

It's a difficult subject to get a grasp on at times. Many programmers
get to the stage of knowing what RGB is, and thinking there is not
much more.

>> Setting VideoLUTs has been standard in display systems almost
>> forever. Find a way of implementing support in Wayland, so
>> that color management can happen in Wayland.
> 
> No.

I think you need to be a whole lot more flexible here,
if progress is to be made. I'm open to other ideas on
how to manage this, but "no, it's not possible"
does not work towards this. Progress might be
made if you or others with a better grasp of
Waylan's architecture at least understand why, and what,
rather than simply saying "No" without any understanding.

> The problem here starts with 'it's not even a complete solution',
> continues on via 'colour control within display hardware is now more
> complex than you realise', and ends with 'this is limiting enough to
> be the worst of all possible worlds'.

I'm not sure what you are talking about.

> You keep repeating this solution as axiomatic; if it really is the
> only possible option for you to work with Wayland, then I thank you
> for your interest in discussion and wish you the best in your future
> endeavours.

Cool. I've tried. We'll see how things progress. I'm
sure Richard can manage something by creating a RedHat/Gnome
specific solution of some sort, although I'm not
sure how people will be able to go beyond the tools
he provides for it. I was hoping to do something
more general and capable.

> Reading you reiterate this yet again, I'm stunned that you want to
> explicitly design for a system where a core and indispensible
> component of the rendering pipeline, is incapable of correct
> rendering.

Sorry, I don't know what you mean by that. Can you be more
explicit in what you mean by "core and indispensable
component of the rendering pipeline", and "is incapable of
correct rendering" ?

> I understand how and why that came to be, but this is not
> the system we are designing here.

I'm afraid I'm not following.

> The entire reason it's taken this long for this discussion is because
> it was kicked into the long grass a couple of years ago.

Yep.

> It was
> delayed specifically to allow the entire ecosystem (Wayland itself,
> the compositors and toolkits, applications, plus rendering and display
> control APIs) to mature enough to let us design a credible solution.
> 'Everything is going to be bad so let's let apps bypass and drive it'
> is not that solution.

I understand. But is the discussion now too late ? Have various
assumptions been baked into Wayland that cripple the options
for color management ? I don't know.

> Privilege being pretty important, when you care about security.

Agreed.

> Therein lies a problem ... if you have decided that the only solution
> is external tools. Given that you're an external tool vendor, it's an
> understandable point of view, but it's not mine, or that of many
> others.

If you have other approaches in mind, please share them.

> Niels, I think conceptually you have the foundations of a good system
> in this proposal. I need to do some more looking into colour
> management (bit of light reading for Christmas), so hopefully I can
> have some more pertinent questions and suggestions after that.

It would be great if others did a bit of that too, so that
there is more chance of some of things I've said being
understood, or even taken seriously. (And yes, I will continue
to poke away at understanding Wayland a little better.)

> This thread has been enough of a catastrophe so far that it's taken me
> around half a day to actually properly read through it, and even then
> I skimmed some of the more egregiously pointless parts.

Yep - I've spent far too much time on it too.

> Graeme, you obviously have a vast depth of colour management
> expertise, and I hope this is something we can make use of, but your
> attitude is shocking and your net contribution to this thread has to
> be negative.

I'm sorry if it has been perceived that way, but I also think
that the reaction from some others has also been arrogant and
less than helpful.

Regards,
	Graeme Gill.