Is there any elegant (read: not too taxing on performance or data volume) way of making an object behave the exact opposite than with the "additive" blend mode?
For example, if the object is a pixel with the RGB values 0-50-0 and it's in front of a pixel with 100-100-100, I need the resulting pixel that's actually displayed on screen to be 100-50-100.
I've experimented with opacity settings and gamma values in the overlaying object, but they don't seem to work in any way that can give me the exact results I want.