At 02:35 PM 12/11/03 -0500, Tyler Durden wrote:

Variola wrote...

"How do you know the signature of the unaltered carrier-medium? E.g., have you measured the LSBit noise from my camera recently? Under which lighting conditions?"

Well, having done some optical signal processing (and getting a patent in that area, come to think of it), I imagined that most photos will naturally have some image noise in certain frequency bands...

You are *way* too FT based in your thinking. There are *many* other measurements and statistics and co-relations. And the noise I was referring to is in part electronic noise, not image noise in either the spatial freq. or poisson sense. The point being that there is info that is perceptually insignificant, that you can replace with compressed encrypted bits.