I have some images with HDR content that I’d like to export from ART. I see there are some formats that say they support HDR: JPEG-XL, AVIF, and HEIC.
However when I select them there are no options for setting things like compression ratio. The resulting files seem to be rather small too. A 3840x2160 image that results in a 42MB 16 bit PNG comes out at just 1MB in JXL. I know it’s an efficient format but it does look a bit over-compressed in places.
What is the best way to export an image in HDR from ART? Ideally I’d like it to be lossless.
The above output formats are implemented as plugins. IIRC none of them use truly lossless settings, but e.g. the JPEG-XL one uses a “visually lossless” compression ratio. If you have examples of artifacts feel free to share them here (along with the original raw file if possible) and I can have a look.
Otherwise, if you want truly lossless, 32-bit float TIFF would do, and then you can do the conversion separately (or write your own custom export plugin).
Ignore the incorrect tone mapping for the JXL output. You can see it’s got some haloing that isn’t there in the original image. It’s very minor and arguably visually lossless, but it’s there. The nature of the noise has changed as well, and looks like compression artefacts to me. Probably not worth worrying too much about.
Hi,
Thanks for the example. I think you need to look at it with the right transfer function applied though to be able to determine if it’s going to be a problem…
