The basic technical approach of the current DRM systems is sound, which is why they're a problem. High quality implementations would restrict people.
In terms of pattern recognition, you're not exactly doing facial recognitiion. The hard part would be putting a signal in there which was:
- distributed through the whole picture (so you can't just mask off the logo in the corner)
- sufficiently unobvious to humans threshold so that quality doesn't go down too far. Dunno about this one, apart from the fact that we have a lot of bandwidth here to hide a signal
- could survive basic disruption attempts by 'hackers' (colour filters etc)
It is a fairly tall order, but so is convincing the entire PC parts industry to put crypto in all their components against the interests of their customers.
e.g. the output of a video camera could be tagged with "allow 3 copies only". Each DRM-aware copy produced would decrement the # of allowed copies. The copied file would have an allowed-count of 0.
If a EURion-like image triggered this mode on the camera then that would probably be sufficient for manufacturers to avoid liability, but still serve to effectively close the "analog hole" (not really analog, but hey).
Yes, it all does seem unlikely. But so does tagging of printer output with yellow dots and EURion, and DRM in general.
http://en.wikipedia.org/wiki/Printer_steganography