PS would certainly be an obvious option, but I didn't mean it would be the only one.  Frankly, I strongly suspect a lot of stuff like that could be done with combinations of mats, shaders, lights, and other manipulations, perhaps combining renders, which I guess would lead to PS or some equivalent.

A lot of experimentation would certainly be in order, and that can't be a bad thing!  Stuff discovered along the way could enrich one's experience, perhaps others' as well, i.e., marketplace, freebies, tutes, etc.  That's a beautiful painting there, BTW.

Edit: Or at least there WAS a beautiful painting there, LOL!  Seems to have vanished.