Good question!
It has not been stipulated as being a requirement but a few things to keep in mind:
- The goal of this VWG is to propose a model that fixes artefacts. If we can do so knowing that the mathematical foundations are sound and will not produce some, the better.
- When we authored the RAE paper in 2017, trying to get smooth derivatives was a strong wish for future updates of the RRT which is exhibiting quite a bit of wobbliness. The SSTS is authored with that in mind and it does make sense to continue that trend to me because it is a) good practise and b) a safety line.
I don’t know if it can be trivially done but would certainly be worthwhile.
Now besides that, I subjectively think that the Reinhart curve is doing a too much aggressive work and I don’t really like because of that. I think (and this is not subjective) that we should strive at keeping the maximum saturation possible, something OOG for ACEScg or BT.2020 is a very narrowband emitter and thus we should keep its saturated quality as long as possible.
Because a picture is worth a thousand words…
The image on the right certainly does not preserve either the physical, i.e. narrowband emitters, or the creative intent of the glowing spheres, the compression is simply too aggressive. People working at Animal Logic, e.g. @alexfry or Illumination, e.g. @ChrisBrejon are clients for such saturated imagery.