Re: HTML Canvas - Transforms for HDR and WCG

(tangent / off-topic) --

I see these use the A2B* tags from the old ones you provided to me years
ago for colorist. It is interesting to see the same technique applied from
those but with a 203 nits reference white:

>colorist identify "Colorbars in PQ 203 display.png"
[   action] Identify: Colorbars in PQ 203 display.png
[   decode] Reading: Colorbars in PQ 203 display.png (23191 bytes)
[ identify]     Format: png
[    image]     Image: 1920x1080 8-bit
[  profile]         Profile "Rec.2100 PQ W203"
[  profile]             Size: 30780 bytes
[  profile]             Copyright: "Copyright 2019 Adobe Systems
Incorporated"
[  profile]             Primaries: BT.2020 (r:0.708,0.292 g:0.17,0.797
b:0.131,0.046 w:0.3127,0.329)
[  profile]             *Max Luminance: 203 - (lumi tag present)*
[  profile]             Curve: complex(-1)
[  profile]             *Implicit matrix curve scale: 49.26*
[  profile]             *Actual max luminance: 9999.78*
[  profile]             CCMM friendly: false
[  profile]             MD5: 5491e070ece4a532bdabbd9ee9b2d0c6

(I'm sure my colorist is making all kinds of awful assumptions here, but
this result seems to make sense to me, which is neat.)

I suppose browsers implement A2B* tags? Is that done via a slow path /
software, or are their chains viable to implement in a shader?


On Wed, Apr 28, 2021 at 9:32 AM Lars Borg <borg@adobe.com> wrote:

> Enclosed is a set of images in various color spaces, including HDR, with
> ICC profiles.
>
> They all look the same in today’s browsers (tested Safari, Chrome, Firefox)
>
>
>
> These images can be used for validating Chris Cameron’s concepts.
>
> Color matching without ICC profiles will require display-referred
> conversions for HLG.
>
> Please try.
>
>
>
> Lars
>
>
>
> *From: *Lars Borg <borg@adobe.com>
> *Date: *Thursday, April 1, 2021 at 11:52 AM
> *To: *Christopher Cameron <ccameron@google.com>, Simon Thompson <
> Simon.Thompson2@bbc.co.uk>
> *Cc: *"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: *Thu, 01 Apr 2021 21:51:37 +0000
>
>
>
> If you are doing an image browser for arbitrary images and thus arbitrary
> color spaces it would be awkward to have to locate a proper image-specific
> color transform.
>
> Can’t we just use the info that comes with the image?
>
> If blending with text “Buy Now” the blending should be in the same color
> space for all images, or else we would need unique text color values for
> each image.
>
>
>
> Lars
>
>
>
> *From: *Christopher Cameron <ccameron@google.com>
> *Date: *Thursday, April 1, 2021 at 8:13 AM
> *To: *Simon Thompson <Simon.Thompson2@bbc.co.uk>
> *Cc: *Lars Borg <borg@adobe.com>, "public-colorweb@w3.org" <
> public-colorweb@w3.org>
> *Subject: *Re: HTML Canvas - Transforms for HDR and WCG
>
>
>
>
>
>
>
> On Thu, Apr 1, 2021 at 3:35 AM Simon Thompson-NM <
> Simon.Thompson2@bbc.co.uk> wrote:
>
> Hi,
>
>
>
> One further thought from me, the proposal last night depended on using a
> certain image import function which allowed the user to dictate a target
> colour space and transform set.  Does a similar video import function exist?
>
>
>
> Yes! It's the same function, createImageBitmap
> <https://nam04.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdeveloper.mozilla.org%2Fen-US%2Fdocs%2FWeb%2FAPI%2FWindowOrWorkerGlobalScope%2FcreateImageBitmap&data=04%7C01%7Cborg%40adobe.com%7C51627b89412443af86db08d8f539c7a8%7Cfa7b1b5a7b34438794aed2c178decee1%7C0%7C0%7C637528975802643088%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=SG%2F3IEUmOUzFfgfZcUj2dVsKuxC97aRKcydTLNL9XvQ%3D&reserved=0>,
> and it takes as input: images, SVG, video, canvas (so you can draw your
> canvas into your canvas), and blob (not-yet-decoded image). The options
> include a "colorSpaceConversion" option, which is currently "none" or
> "default". This is where I think we should consider adding a well-defined
> perceptual colorimetric intent (and this intent wouldn't be
> path-independent).
>
>
>
> When the input is a blob (a not-yet-decoded image), the color space
> conversion can happen simultaneously with image decode.
>
>
>
>
>