Re: Pre-meeting Thoughts on HDR Canvas

To be fair, I could probably argue the exact opposite direction, something
like what Lars said (slightly massaged):

We could just offer srgb (the normal, SDR current kind), extended SRGB @ X
nits (HDR on), and extended linear SRGB @ X nits (HDR on), and offer
*nothing* else. If you ask for it in an ImageData, you get floats, and it's
up to your fancy WASM/JS to "do things".

I prefer more dials, but I did like Lars' point about cutting out
degenerate combinations. It could be as simple as error'ing out of
getContext() on certain "bad" combinations, though.



On Tue, Jan 26, 2021 at 5:22 PM Christopher Cameron <ccameron@google.com>
wrote:

>
>
> On Tue, Jan 26, 2021 at 11:51 AM Joe Drago <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.
>
>