Re: HTML Canvas - Transforms for HDR and WCG

In this context any ICC profile with headroom above SDR white is applicable. 
Adobe currently ships such profiles, all having a significant headroom. Also attached.
This covers both cine camera profiles and HDR profiles. All are V4 profiles.
AFAIK, there are more such profiles in the market place.
(Adobe started shipping such profiles in 2006)

ARRI LogC3 Wide Color Gamut - El 160
ARRI LogC3 Wide Color Gamut - El 1600
ARRI LogC3 Wide Color Gamut - El 800
Canon Cinema CLog2
Canon Cinema CLog3
e-sRGB
P3 D65 PQ W203
P3 D65 PQ W300 
P3 PQ Display Full
Panasonic V-Gamut V-Log 
Rec.2100 HLG Scene W63
Rec.2100 HLG Scene W75
Rec.2100 HLG Scene W81
Rec.2100 HLG W100
Rec.2100 HLG W203
Rec.2100 HLG W300
Rec.2100 PQ W100
Rec.2100 PQ W203
Rec.2100 PQ W300
Rec.lTU-R BT.2100 HLG Scene Full
Rec.lTU-R BT.2100 HLG Scene Narrow
Rec.lTU-R BT.2100 PQ Display Full 
Sony S-Gamut3.Cine/S-Log3 
Sony S-Gamut3/S-Log3 
Universal Camera Film Printing Density


A user can embed any of the above profiles in these file formats with these extensions (using Photoshop). 
Other tools can support other formats.

psd Photoshop
psb Large Document Format
eps Photoshop EPS
jpg  JPEG
jpf  JPEG 2000
jps  JPEG Stereo
mpo  Multi-Picture Format
pdf  Photoshop PDF
png  PNG
tif  TIFF

Not tested if these work with SVG.

ICC profiles provide a color transform from RGB to XYZ D50.
ICC profiles do not provide colorimetry info in the style of an ISO 22028 color image encoding specification. 
These profiles do not do tone mapping, but preserve the headroom.
The relative colorimetric intent, present in all of these profiles, together with the chad tag, provides colorimetric values for each RGB value.
A few of the profiles indicate scene-referred colorimetry.
A few of the profiles indicate nits for graphics white.
A few of the profiles contain the draft CICP tag.

The ICC profile is embedded in the wrapper, not in the codec data (AFAIK). 
Besides the ICC profile, there is no colorimetry info in the files.

Lars

-----Original Message-----
From: Pierre Lemieux <pal@sandflow.com>
Date: Monday, May 3, 2021 at 5:07 AM
To: Lars Borg <borg@adobe.com>
Cc: Christopher Cameron <ccameron@google.com>, Chris Lilley <chris@w3.org>, "public-colorweb@w3.org" <public-colorweb@w3.org>
Subject: Re: HTML Canvas - Transforms for HDR and WCG

Hi Lars,

I think the group will need details before the group can take any
meaningful action:

- file format(s) used
- codec(s) used
- colorimetry metadata within the codec (if any)
- colorimetry metadata within the file (if any)
- colorimetry metadata within the ICC profile
- etc.

Best,

-- Pierre

On Mon, May 3, 2021 at 12:13 AM Lars Borg <borg@adobe.com> wrote:
>
> The images with hlg and pq encoding and icc profiles already exist. Started several years ago afaik. If you need to know I can find out when we shipped our first such profile.
> Doing an hdr canvas with these images would be new.
>
> Thanks,
>
> Lars Borg
> Adobe
> Hawaii
>
> ________________________________
> From: Pierre-Anthony Lemieux <pal@sandflow.com>
> Sent: Sunday, May 2, 2021 2:29:04 PM
> To: Lars Borg <borg@adobe.com>
> Cc: Christopher Cameron <ccameron@google.com>; Chris Lilley <chris@w3.org>; public-colorweb@w3.org <public-colorweb@w3.org>
> Subject: Re: HTML Canvas - Transforms for HDR and WCG
>
> > Legacy.
>
> I do not see legacy playing a role here since HDR is new to the web.
>
> On Sun, May 2, 2021 at 5:03 PM Lars Borg <borg@adobe.com> wrote:
> >
> > Legacy.
> >
> > Lars
> >
> > -----Original Message-----
> > From: Pierre Lemieux <pal@sandflow.com>
> > Date: Saturday, May 1, 2021 at 2:26 PM
> > To: Christopher Cameron <ccameron@google.com>
> > Cc: Chris Lilley <chris@w3.org>, "public-colorweb@w3.org" <public-colorweb@w3.org>
> > Subject: Re: HTML Canvas - Transforms for HDR and WCG
> > Resent-From: <public-colorweb@w3.org>
> > Resent-Date: Saturday, May 1, 2021 at 2:26 PM
> >
> > > To the original question of "what to do about ICC profiles specifying HLG anonymously?".
> >
> > What is the use case for not specifying the pixel color scheme?
> >
> > Best,
> >
> > -- Pierre
> >
> > On Sat, May 1, 2021 at 5:19 PM Christopher Cameron <ccameron@google.com> wrote:
> > >
> > > On Thu, Apr 29, 2021 at 10:34 AM Chris Lilley <chris@w3.org> wrote:
> > >>
> > >>
> > >> On 2021-04-28 15:23, Christopher Cameron wrote:
> > >> > In all browsers today, for "Colorbars in HLG 203 display.png", any
> > >> > signal value above 0.75 is clamped to SDR-white.
> > >>
> > >> The choice of 0.75 follows from the HLG specification - a code value of
> > >> 0.75 is media white, while a code value of 1.0 is peak white and is 12x
> > >> higher luminance.
> > >>
> > >> The choice of clamping all HDR highlights, with no tone mapping is an
> > >> easy but bad one. However, dislaying HDR content on SDR is in general
> > >> hard; HLG is easier here than PQ (by design).
> > >
> > >
> > > Suppose we have a video that identifies itself as HLG (not anonymously), and is displayed using a <video> tag on an SDR device.  Should it clamp values above 0.75? My answer is "no".
> > >
> > > We have established that it is inevitable that pixel values over 0.75 in an image with the ICC profile "Colorbars in HLG 203 display" will be clamped.
> > >
> > > To the original question of "what to do about ICC profiles specifying HLG anonymously?". My answer would be "treat them as extended SDR, not as HLG, and there is no way for them to truly be the same as HLG".
> > >
> > >
> >