I might be wrong here (so please someone correct me if i am), but is this reverse gamma thing all about going from 2.2 gamma space to 1? If it is so, then i think it can be done in Photoshop by lowering the levels by half. So assuming that 2.2 is 1.00 then levels value in Photoshop should be 0.6 and not 1.00.
Just some thoughts. Might be a bulls**t talk as well
Ps. Sorry 8bstudio for hijacking your thread like this.