There seems to be a new HDR image format gaining some traction. I haven't got a good understanding of them yet, so I am just writing down some very rough notes: Gain Map spec draft by Adobe: https://helpx.adobe.com/nz/camera-raw/using/gain-map.html This seems to be in the process of being standardized as ISO/CD 21496-1. A website with some info on gain map: https://gregbenzphotography.com/hdr-photos/jpg-hdr-gain-maps-in-adobe-camera-raw/ ## File format support: Google's "Ultra HDR Image" format: https://developer.android.com/media/platform/hdr-image-format This seems to be a format Google has developed to encode gain map data into JPEG in a backward-compatible way. They also have a library for handling this: https://github.com/google/libultrahdr (This seems to be slightly different from Adobe's JPEG gain map, but I haven't found the spec on that.) Apple seems to use gain map in their HEIF photos (needs checking). libavif and libjxl has experimental gain map reading and writing support API. ## Support in other software (as far as I know): - Adobe Camera Raw seems to be able to output JPEG gain map images. - Chrome is able to read and render such JPEG images (tested on Windows) - Ultra HDR is supported on Android 14 - Google Pixel Camera can save Ultra HDR (tested on Pixel 6) ## Relevance to Krita: - Krita may want to be able to import these files as HDR format. - This format may be a good candidate for exporting HDR painting.
Importantly: ## File format support: Imagemagick already has support for libultrahdr and conversions with HDR gain maps (and i.ex: archlinux has libultrahdr and imagemagick support). Example command to create an UltraHDR JPEG: https://github.com/ImageMagick/ImageMagick/pull/7198#issuecomment-2381592909 # Support in other software Adobe Lightroom, Instagram and others also support it. Information about all the software support with HDR gain maps in HDR Photography: https://gregbenzphotography.com/hdr The camera apps of the latest Samsungs, Oneplus, Pixels and others support shooting it. And all devices since Android 14 display it.