What would be neat is a polite discreet social signal that politely discreetly signaled this to people with a camera. If you did it right, you might also get rich in a Pet Rock sort of way.
If you politely asked, I would generally delete the picture, depending on whether or not there was a reason that I felt I wanted the picture and whether or not there was a way to reproduce the picture without you in it. For example, if Bigfoot had run through the frame while I was taking the picture, I'd be less likely to delete it.
If you purposefully made a picture of me and refused to delete it things could get interesting.
I'd be very interested to learn what "things could get interesting" means - as would the police, depending on the definition of "interesting."