Indeed, a gamma curve would be great. But due to limiting BRAM (no blocks are left atm), an option would be piecewise linear approximation. But maybe in a further step. For now I’m quite happy.
Could you also take a look into your reverse LPF implementation? I integrated it more deeply into the post-processing pipeline.
The contrast values are chosen to 0% (Off), 25% (Low), 50% (Medium) and 75% (High) but are discussable. 100% for high would be possible, too – of course ^^