Re: Detecting double compressed jpegs

Stefan wrote:

For a project that deals with tampered images, I need a "tool" that
detects double compressed jpegs.
I found the following paper which describes how to do it, but I fear I'm
not able to implement it by myself.

http://www.cs.dartmouth.edu/farid/publications/ih04.pdf (page 7)

Directions to some piece of code that detects double compressed jpegs,
or helps implementing it would be very welcome.

I afraid I won't have such a tool handy, but after browsing thru the provided document (thanks!) I've the impression that the proposed method to detect doubly-compressed JPEGs is a bit naive. A suitable JPEG requantizer might be able to avoid the mentioned artifacts. But then, if you load the image into an image editor and save it back from there, the software will likely be not "smart enough" to avoid them.

So long,
Thomas
.