Greg B

> Maybe to emphasize the point that tonemapping is probably a bad idea (at least without the explicit instruction to do so and/or as the only way possible/the default way...

Google has shared a reference implementation and other Ultra HDR JPG resources at https://github.com/google/libultrahdr

@jcupitt Sounds good. For conversion to other HDR formats, do you see that actually getting used? The loss of SDR is a huge quality issue in terms of adapting to...

@snibgo There are some gain map examples under the Adobe link (direct download is https://www.adobe.com/go/gainmap_sample_photos). Your question on other operations is a good one. I would say the support I...

> If the gain map is pixel data (same size as input), then could it not be put into a meta channel? What's a beta channel? One thing to note...

@snibgo I would be happy to help test any gain maps you convert. You can reach me directly via gregbenzphotography.com/contact/ The Adobe AVIF images would be a also good option...

> meta channel (not beta channel) is an extra channel apart from RGBA for example. TIFF supports extra channels that it uses for example as masks. But they can be...

@snibgo Does jpeglib or the info from madmanchan cover what would be needed for IM to add support for JPG gain maps? (I can't offer much on your question on...

JPG gain maps (aka "Ultra HDR JPG") are now supported in 4 browsers: - mainline Chrome v116 (enable via chrome://flags/#gainmap-hdr-images). - Brave v1.57.47 (via brave://flags/#gainmap-hdr-images) - Opera v101 (via opera://flags/#gainmap-hdr-images)...

@fmw42 Thank you for the update! I'm sure there's a lot of detail to process two images in the same file.