While we're busy recommending modules, I'll advice you to take a look at Image::IPTCInfo. That module is capable to extract and insert the metadata-info in image files, in the various formats that Photoshop has used over its generations. For example, for the latest Photoshop incarnation, that is the XMP format (a 100k PDF file), XML embedded into image files.

OTOH, when we're talking about thiefs, I don't think this kind of mark is even remotely robust.