Auto-Exposure

I was futzing around with Ambient Light in the GemFX today and liked the effect happening with darkness adaption when bright light sources are present. But for this particular game I'm playing the problem is that I need brighter shadows, but thought it would be really great to emulate a camera auto-exposure effect, where if the screenspace is predominantly dark then the brightness or exposure of the screen raises, lightening up those dark areas. And when the screen is predominantly bright, the brightness or exposure is reduced (kind of like what already happens in the Ambient Light adaption) to make highlights look proper and not completely blown out.

Is this perhaps already a functionality that I missed or a viable feature to add?

For now you could simply activate a LiftGammaGain shader before or after (different effects) the ambient light shader to adjust shadows. AL adaptation will then adjust its exposure.