- From: Leo Barnes <lbarnes@apple.com>
- Date: Wed, 15 Nov 2023 21:23:38 +0100
- To: Pierre-Anthony Lemieux <pal@sandflow.com>
- Cc: Chris Lilley <chris@w3.org>, "Portable Network Graphics (PNG) Working Group" <public-png@w3.org>
> On Nov 15, 2023, at 20:47, Pierre-Anthony Lemieux <pal@sandflow.com> wrote: > >> Thanks for that data, although it mainly covers JPEG-compressed images. > > I think I understand gainmap in the context of compatibility with JPEG > 1, which is ubiquitous and cannot support HDR natively. > > I am not sure how this applies to PNG and other formats that can > support HDR natively. Please see these points made earlier: > But gain maps that allow you to go from HDR->SDR are also highly useful. They allow: > 1. Imaging pipelines to provide their own "look" for how an HDR image should look as SDR. Local tone-mapping from HDR to SDR is non-trivial and highly subjective and pipelines may want to apply their own artistic effects. > 2. A defined way of interpolating between HDR and SDR. Highly useful when your display does not have the headroom to fully display the HDR content. Cheers, //Leo > > On Wed, Nov 15, 2023 at 11:12 AM Chris Lilley <chris@w3.org> wrote: >> >> Thanks for that data, although it mainly covers JPEG-compressed images. >> >> I would be interested to see a comparison between, for example: >> >> 8 bit PNG compressed SDR image plus 10 bit PNG compressed HDR image >> 8 bit PNG compressed baseline SDR image containing un-resampled 16-bit gain map >> >> both in terms of file sizes and also in terms of per-pixel error visualization in the reconstructed alternate image. >> >> On 2023-11-15 14:03, Leo Barnes wrote: >> >> The claim of storage efficiency has not been backed up by any measurements that I have seen. >> >> >> It's in the white-paper published by Adobe: >> >> -- >> Chris Lilley >> @svgeesus >> Technical Director @ W3C >> W3C Strategy Team, Core Web Design >> W3C Architecture & Technology Team, Core Web & Media >
Received on Wednesday, 15 November 2023 20:25:34 UTC