The copymove implementation you put forward is very nice code, but it's pretty slow for larger images unless you've changed it recently. Dr. Krawetz wrote a blog post about how to speed it up here:
That site also has a tool that allows one to estimate the quality level the JPEG was last saved at, as well as a lot of good information for anyone else interested in image analysis.
http://www.hackerfactor.com/blog/index.php?/archives/2009/08...
That site also has a tool that allows one to estimate the quality level the JPEG was last saved at, as well as a lot of good information for anyone else interested in image analysis.