I’ll try to write a longer post later, but here is already a quick description of the modules that I typically use. If you are interested, I also posted some HDR edit (with the XMP) in this Play Raw.
Here is the style file I currently start from: Default PQ v2.dtstyle (4.5 KB)
After applying it, I’ll disable all the modules above (and including) exposure·1, edit the midtones, then reapply the modules one-by-one from bottom to top.
The most relevant modules here are:
highlight reconstruction: Set to “reconstruct in LCh” to ensure that any RAW clipping smoothly fades to white (the default “inpaint opposed” makes it look magenta and works best iffilmic rgbis used later.exposure: To adjust the exposure of the midtones, using the white frame as reference (light bulb on the bottom right). Expose as usual, with midtones around 18% grey, but ignore the highlights at this stage.rgb curve: I apply some “foot” / shadow roll-off in order to recover contrasty, deep blacks in the shadows, that usually contain a significant amount of noise — forming some “veil” even after noise reduction — because I exposed for the highlights. This has to be adjusted for each scene, usually by eye, zooming in some dark area. The upper part of the curve is linear so that I don’t mess with the contrast in midtones and highlights.
RGB curve example
exposure·1: The -5.622 EV “PQ scaling”.tone equalizer: I sometimes use more than one tone equalizer module (one for midtones and one for highlights). Since this one is after the PQ scaling, I use it to darken the strongest (and sometimes distracting) highlights, so that they stay within 2 or 3 EVs of HDR overrange. Here, I use an external viewer to assess the result.base curve: A predefined curve that is linear in the SDR range but then smoothly rolls-off the highlights, up to some predefined brightness (here 1600 nits or 16% of the PQ range). This is mostly to ensure that even the strongest specular highlights are mapped to reasonable values.
The other modules aren’t really specific to HDR:
white balance&color calibration: Used for white balancing. Either to fine-tune the camera-chosen white balance, or to set it manually (necessary if, for instance, I used UniWB to precisely expose to the right).lens correction,orientationanddiffuse or sharpen: Mainly corrective modules. For the latter, I use the “sharpen demosaicing: AA filter” preset because my camera has an AA filter.astrophoto denoise: The noise reduction algorithm that looks best to my eye. I usually don’t try to reduce luma noise because I prefer some “grain” to losing details, so I setchromato 100% and just tune thestrengthparameter. But this is really a matter of taste.
Feel free to post your AVIF files here (zipped because otherwise Discuss will refuse them), so I can have a look at them with the Adobe viewer (which is more-or-less the reference implementation for those HDR and gain map standards).
Yep, HDR editing is still a bit experimental and hacky, unless you use one of the few commercial apps that supports it… Hopefully the situation will eventually improve, even on Linux, thanks to the current standardisation efforts and the push from some large industry players 