Re: [EXTERNAL] Re: Pre-meeting Thoughts on HDR Canvas

Or PQ-BT.2100

From: Christopher Cameron <ccameron@google.com>
Date: Tuesday, January 26, 2021 at 8:27 PM
To: Joe Drago <jdrago@netflix.com>
Cc: "public-colorweb@w3.org" <public-colorweb@w3.org>
Subject: [EXTERNAL] Re: Pre-meeting Thoughts on HDR Canvas
Resent-From: <public-colorweb@w3.org>
Resent-Date: Tuesday, January 26, 2021 at 8:26 PM



On Tue, Jan 26, 2021 at 11:51 AM Joe Drago <jdrago@netflix.com<mailto:jdrago@netflix.com>> wrote:

Export / Save is a weird one, but important. Chris' slides will go into detail on this one (ImageData / ImageBitmap), but I just wanted to note that transfer functions play a much different role here, and due to file format limitations, we might want a few more selections here, notably PQ and HLG. I obviously have a bit of a bias with HEIF-derived formats (AVIF , HEIC), but I think 10bpc P3/BT2020 PQ/HLG images are going to be too useful/common as an export format to not have some bidirectional mechanism for those profiles, even if we don't actually do the direct final encoding to any of those formats.

Yeah, I think export/save will need some more parameters. There are some obvious things (like, a uint8-p3 canvas should be saved that way), but I think many others will need explicit controls.

Being able to ask the canvas for "please give me unorm16 BT2020 PQ" would be an incredible feature in today's world of WASM-compiled encoders.

Yeah, one of the topics to discuss next meeting should probably be adding rec2020-pq named color space (it's down there in the "for future consideration" section).

As you mentioned in some of the earlier sections, indeed, we will probably want to lean in to some more color spaces especially in the context of what CSS Color Level 4 offers.