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I'm wondering - is there a steganography solution for digital images which is resistant to image manipulations? With "manipulations" I mean the most standard operations - recompressing JPEGs (or even changing file formats entirely), cropping and scaling. The application of this method would naturally be for image copyright protection.

I fully understand that the more image is manipulated the less are the chances that the steganographic watermark is intact, but at least some degree of resistance would be nice.

+4  A: 

It seems to me, that this is just another move in the cat and mouse game, but here you are:

http://scien.stanford.edu/class/ee368/projects2000/project5/default.htm

From the conclusions:

"There will always be a tradeoff in watermark embedding. By which we mean tradeoff between robustness of the watermark verses the degradation of the image. At some point the strength of the watermark will cause the image to be degraded to a point, which will not be acceptable.

Depending on the technique used for watermarking, whether in spatial or frequency domain, the watermarked image showed, in general, robustness to the attacks of the same domain and weakness to the attacks in the opposite domain. Nakamura mentions these results in his work, and concludes that there is no method that will be robust in both domains, and that applying hybrid watermarking schemes will have worse results."

mbarkhau
I suppose that if one knew what algorithm was being used and was determined to deliberately remove (or cripple) the watermark, it would indeed be very difficult to stop him. However the vast majority of image thieves are simple users that don't think much about these things (or so I believe - I don't have any data). It would be already a good step forward to protect against them.
Vilx-