Duplicate images

I've been using Dup Detector to find duplicate image files (damn you 4chan). I've just found out that it doesn't detect .gif files though.
Are there any programs that work the same as Dup Detector, but can support gifs?

What the fuck? Why would he convert the images? And why is a duplicate detector limited by filetype? Duplicate detectors use hash checking, there can be no filetype for all it matters.

I use CloneSpy, it seems to be the gold standard and most well established.
http://www.clonespy.com/