Surveillance cameras that notice aberrations

From John Twelve Hawks’s “ How We Live Now” (2005):

And everywhere we go, there are surveillance cameras – thousands of them – to photograph and record our image. Some of them are “smart” cameras, linked to computer programs that watch our movements in case we act differently from the rest of the crowd: if we walk too slowly, if we linger outside certain buildings, if we stop to laugh or enjoy the view, our body is highlighted by a red line on a video monitor and a security guard has to decide whether he should call the police.