as an amatuer photographer, i can tell you pixels are pixels. no matter what you do, it is very difficult to enhance an digital image or video without losing detail. And it is this lack of detail that will make it obvious. Take DTSV sports channels, especially the football ones. on a large tv screen, you can immediately tell as the pixles are flying all over the screen. I dont know how they do it in the movies.

 

please look at this fake image. http://www.worldsfamousphotos.com/tag/fake