Re: Discuss HDR at CSS WG next week ?

On Thu, Sep 15, 2016 at 7:35 AM, Mark Watson <watsonm@netflix.com> wrote:

> > On Sep 14, 2016, at 10:05 PM, Rossen Atanassov <
> Rossen.Atanassov@microsoft.com> wrote:
> >
> >> On Wed, Sep 14, 2016 at 16:53:53, Mark Watson wrote:
> >>
> >> I have some use-cases and issues / questions related to High Dynamic
> Range
> >> graphics / images and how they could be supported in CSS. I wondered if
> this
> >> topic was or could be on the agenda for next week ?
> >
> > Are you referring to our TPAC agenda? If so, we don't have the topic
> scheduled and looking through everything we have it is doubtful we could
> get to it.
> >
> > Could you summarize your proposal? Is this something proposed at WICG
> already?
>
> Yes, TPAC. I've raised the issue of HDR a few times on the CSS list,
> but with no real response. We had a breakout at TPAC last year, but no
> one from CSS attended. I imagine that is because people do not yet
> have real hardware / platform APIs with which to play with this
> functionality. Those will soon be available, so it seemed good timing
> to raise it again and explain the various problems.
>
> I only have problems, not a proposal. The basic problem (as I
> understand it) is that with HDR displays, users are unlikely to want
> the peak white for regular sRGB to map to the peak luminance of the
> display. That would make desktops blindingly bright. So there needs to
> be a way for pages to signal when they are providing data in the sRGB
> luminance space (where peak white is what the user has set as a
> comfortable luminance for their desktop according to current ambient
> light) and when they are providing data in a different luminance
> space, where peak white is brighter (exactly how bright is one of he
> questions to be answered.)
>

This is defined in the CSS color spec [1]. If no profile is provided, peak
white is peak sRGB white.
The fact that you get blindingly white is a browser bug. (I believe only
Safari does this right today)

If you do provide a profile, it will be used to map to the display.
Is there a way to embed a profile in a video stream?


> If the WICG is the appropriate place to raise these problems, I can do
> that, but the experts are in CSS WG so I wondered if there was
> interest in learning about these issues.
>
> Thanks ... Mark
>

1: https://drafts.csswg.org/css-color/#color-type