I have this app, "SnapSeed".. I love the way it modifies "ambience" of a picture when you go to Tools -> Tune image. Then you scroll up a bit and raise it's "Ambience" value.

How does it does that? It's awesome and I'd love to do something like that on some videos I've got! Is there a way to do it via avisynth? I'm pretty used to avisynth, and megui also..

But I can't imagine how an effect like that is done. I'm know just the vanilla brightess/gamma/contrast/saturation, bleh!

Please any thoughts...?