cool, thanks again Didee!
well the whole idea is to have big grain in dark stuff, and very fine in bright ones.
maybe a 50/50 would be fine after all ? or at least better than having the same size in dark/bright, and different in mid.
but I've done my tests on a 19" CRT mainly, I'll look more into it this evening on the pj.
I'm not asking for 50/50 stuff because it sucks too much ressources, but simply coz huge grain in dark areas looks a bit distracting and very small one a bit weak.
I'll try to play around w/ the sharpness as SoulHunter said.
and this script is great, even for non realtime use I think