Pan and Scan
Pan and scan is a method of adjusting widescreen film images so that they can be shown within the proportions of an ordinary video screen. During the "pan and scan" process, an operator selects the parts of the original filmed composition that seem to be significant and makes sure they are copied - "scanning." When the important action shifts to a new position in the frame, the operator moves the scanner to follow it, creating the effect of a pan shot. This method allows the maximum resolution of the image, since it uses all the available video scan lines. It also gives a full-screen image on analog television.
One modern alternative to pan-and-scan is to directly adjust the source material. This is very rare; the only known uses are computer-generated features, such as those produced by Pixar, who began the process with their film “A Bug's Life”. They call their approach reframing; while many scenes that are placed in their fullscreen versions are simple pans, many others have the full widescreen image extended with added image above and below. Another method is to keep the camera angle as tight as a pan shot, but move the location of characters or objects so that they all fit in the frame.
SOURCES:
http://en.wikipedia.org/wiki/Pan_and_scan