I could be wrong here, since the bsnes code is more than a bit of a spaghetti tangle, but it looks to me like you inherited a bug where both the gamma ramp kludge and hardcoded 1.5 gamma were applied in retroarch. I see that you fixed the hardcoded 1.5 gamma to a selectable gamma defaulting to 1.0. But it also looks like you accidentally removed the line that was disabling the gamma ramp kludge, at least for the standalone build. (I assume, perhaps wrongly, that the 1.5 gamma in bsnes was meant as a replacement for the gamma ramp that wasn't implemented evenly for standalone and retroarch.)
Especially for retroarch, it would be nice to have an option to get raw R'G'B' so that CRT gamma emulation can be handled properly in shaders.
I could be wrong here, since the bsnes code is more than a bit of a spaghetti tangle, but it looks to me like you inherited a bug where both the gamma ramp kludge and hardcoded 1.5 gamma were applied in retroarch. I see that you fixed the hardcoded 1.5 gamma to a selectable gamma defaulting to 1.0. But it also looks like you accidentally removed the line that was disabling the gamma ramp kludge, at least for the standalone build. (I assume, perhaps wrongly, that the 1.5 gamma in bsnes was meant as a replacement for the gamma ramp that wasn't implemented evenly for standalone and retroarch.)
Especially for retroarch, it would be nice to have an option to get raw R'G'B' so that CRT gamma emulation can be handled properly in shaders.