Super interesting, thanks for the images! I’m curious how much of this appearance phenomena is the software image processing that the images went through on the iphone, and how much is from the Helmholtz-Kohlrausch effect in our visual system.
Dev Update
I’ve pushed a few more changes to my open-display-transform git repo which is now at v0.0.81b3.
- Add alt version of the DCTL which has more user parameters exposed. This may be useful for expert users who wish to play around with the various parameters.
- Simplify and reduce model which allows for continuously varying adjustment of the curve based on a single parameter representing white luminance
Lw(see this post for more details). - Add quasi-perceptual highlight dechroma (as I’m now calling “path to white”) or hue-bias. This is mainly to counter-act Abney effects with blues turning magenta and reds turning pink as they are dechroma’d. It helps a little to resolve perceptual differences between SDR and HDR appearance… though it’s definitely not perfect.
- Little tweaks to the norm weights
- Remove piecewise hyperbolic compression function. The appearance is pretty similar with correctly adjusted parameters and I don’t think the extra complexity is worth it.