At higher settings, I've always found that greycstoration tends to smear color strangely: color on one side of an edge will appear a distance away on the other side of the edge, with a region of clean color between. The major issue I always have is when I've found the level of blurring I want, but when I set it there, the smears start showing up, too.

Added an experimental alternate amplitude calculation which seems to eliminate this problem. It's disabled by default for now, but if nobody finds any problems with it I'll turn it on by default at some point.