Previously, whenever thumbnails were generated by ImageMagick, the sharpen option was used. This was especially helpful for small thumbnails of detailed images. It appears that this option may have recently been turned off judging by the softness of newly generated thumbnails.
New thumbnail (soft):
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Russian_Empire-Full_coat_of_arms.3.jpg/219px-Russian_Empire-Full_coat_of_arms.3.jpg
Cached old thumbnail (sharp):
http://upload.wikimedia.org/wikipedia/commons/thumb/7/7b/Russian_Empire-Full_coat_of_arms.3.jpg/220px-Russian_Empire-Full_coat_of_arms.3.jpg
This seems to have changed around the time of the recent ImageMagick update.
Version: unspecified
Severity: minor