@anon66851888 Welcome to the forum! After a few posts, you should be able to drag and drop files. It would great if we could see your workflow in action.
HLG and PQ are simply transfer functions that convert your image.
Take this 22 EV image (at least according to the website), e.g., from https://hdrihaven.com/hdri/?h=lilienstein. Applying HLG to the [0,255] range gives us this output. (I had to do an extreme clip of the sun prior to applying HLG because it is so much brighter than the rest of the image. If I boost it without clipping, the rest of the image would still be very dark. If I push the curve to the extreme, everything would end up extremely flat.)
Edit Oops, I forgot to answer your question. I basically used GIMP to convert the *.hdr source file to *.tif and then did the clipping and HLG curve application (I hid the actual math in the hlg_ command) on the image with one command as follows:
