Detecting digital manipulations of a picture - software

Hi,
I am searching through the internet since a couple of hours, and
cannot find any trace of a software I used about one year ago, that
was able to detect if and where an image had been manipulated, i.e. by
Photoshop, without having to preprocess/include a watermark
beforehands.
Who could give me the name of such a software ?
Thanks a lot,
jean-Louis
.

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