[nodata]

mogrify -strip imagename.jpg

But it won't help. You could just make your data a real image.

[pfortuny]

You might as well change a single byte. A tiny modification and BANG! nobody notices and the service is pretty useless as a general back-up solution.

They could even implement that in their TOS: "whenever you upload a photo you agree to a random byte being modified on one of the pixels on the border."

[shawabawa3]

It would be pretty easy to stick in some redundancy

[jacquesm]

Decompress and subsequent recompress would do this just fine.

[nodata]

What would do what fine? mogrify -strip removes what he asks...