PNG thumbs are unsharp and there's nothign to do about when you want the thumbs in PNG format:
https://bugzilla.wikimedia.org/show_bug.cgi?id=29659
https://bugzilla.wikimedia.org/show_bug.cgi?id=6205
https://bugzilla.wikimedia.org/show_bug.cgi?id=726
What about an option to return PNG thumbs in JPG (if source is not transparent)?
JPG thumbs of PNG are def sharper. compare yourself: http://www.mediawiki.org/wiki/User:Subfader/PNG_thumbs_unsharp
Version: 1.21.x
Severity: enhancement