I work on a television show that does that sort of effect all the time. Our graphic artist is well-versed in computer technology and knows this isn't possible. So do our directors.
However, in real forensics, there is a certain amount of tweaking and enhancing you can do to get information out of an image. The way it's done on television is an exageration of ability and time it takes to do it, just to keep the plot moving along.