User blog comment:DaNASCAT/Technical Update: September 06, 2011/@comment-4126310-20110908023748/@comment-1656630-20110912190921

Hiyah! I checked, and there doesn't appear to have been a change. Wiki Activity, Edit Counts, and Achievements are all based on Article Pages, so images don't get counted unless they're being added to a change. This is normal.