At the risk of starting another debate, I'll just say this: you don't need anything.

This is what I understand. Images such as those in jpg format are gamma-corrected, or you really couldn't see them all that well. Poser 5-6-7-8 and Poser Pro and Pro 2010 use linear colour information when they process. (Shoot me down, but that's what I understand). If you give the colour processor non-linear (i.e., gamma-corrected) information, the colours won't process correctly.

Gamma-correction has nothing to do with photo-real or anything like that. It has to do with how Poser processes colour. In non-pro versions, you linearise corrected colour in the material room using a set of nodes and then gamma-correct after processing has been done. In the Pro versions, the programme does it for you.

Again, nothing to do with photo-real. Nothing.

ETA: there are formulas that have been written that are more accurate in terms of colour processing along the luminance spectrum than simple GC. BB came up with that formula too. It's around here, somewhere.

Monterey/Mint21.x/Win10 - Blender3.x - PP11.3(cm) - Musescore3.6.2

Wir sind gewohnt, daß die Menschen verhöhnen was sie nicht verstehen
[it is clear that humans have contempt for that which they do not understand] 

Metaphor of Chooks