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darktable-org / darktable

darktable is an open source photography workflow application and raw developer
https://www.darktable.org
GNU General Public License v3.0
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Support HDR gain maps #17399

Open kmilos opened 2 weeks ago

kmilos commented 2 weeks ago

The storage of SDR image + gain map is currently being standardized as ISO/CD 21496-1.

This is already used by Adobe in "enhanced" DNGs, in Google's UltraHDR JPEGs (see also libultrahdr), and by Apple in HDR iPhone HEICs.

libavif and libjxl also added preliminary support for it.

Ideally, both import and export should be supported.

This approach seems to be gathering more momentum in the market compared to e.g. "true" 10-bit HDR only containers.

Related:

https://gregbenzphotography.com/hdr-photos/jpg-hdr-gain-maps-in-adobe-camera-raw/

https://www.reddit.com/r/DarkTable/comments/1f421d0/how_to_export_an_hdr_image_taken_on_iphone/

wpferguson commented 2 weeks ago

There is a PR for a lua script that can export UltraHDR, https://github.com/darktable-org/lua-scripts/pull/502.

The PR also includes instructions on how to create the gainmap.

ralfbrown commented 2 weeks ago

darktable already has some support for gain maps on import (mostly in DNGs, e.g. #10289)

kmilos commented 2 weeks ago

@ralfbrown Not the same thing, that one is for flat field correction in raw domain.

JLTastet commented 1 week ago

Some relevant discussion on pixls.us (where the lua plugin came from) https://discuss.pixls.us/t/manual-creation-of-ultrahdr-images/45004