Thanks for the inputs here, in particular from @AD4K and @flannelhead, which confirms some muddled thoughts of mine – I’m now confused on a steadily higher level.
One question regarding the difference between scene- and display-referred: I’ve understood an important aspect of this to be that not only is the representation of luminance differences linear in scene-referred, but also that it is not bounded in computations. Since nobody mentions this, I wonder if one considers bounded representation to be inherent in non-linear representation – or have I misunderstood here?
From my understanding the data in DT are processed in 32bit float so never bounded but if you use a module with a display referred UI then you can only modify data in that bounded 0-1 range… At least I believe someone told me this or I have messed it up…
I believe I read something to that effect in here…
The difference between scene-referred and display referred is in what the numbers mean.
In “scene-referred”, pixel values are proportional to light energy,
in “display-referred”, those values are proportional to log(light energy), which has (nasty) effects when you use blurs (as in most masking).
I don’t think there’s any reason why display-referred should be bound, that may just be an historical artifact: as a traditional display can’t receive values greater than 100%, the modules concerned weren’t really concerned with values outside the range (0…1). In programming, giving a display-referred module an input >1 would lead to “undefined behaviour” (i.e. anything can happen).
Glad I am not the only one…This is border line bot like… looking back over the few posts by this user they are mostly weird one line questions… sorry @slow if you are real…
This can be tested objectively in newer versions of GIMP or other applications. I am sure there were several posts on this very question, but unfortunately, I cannot find it anywhere!
