(v., adj.) To crop the top and bottom of the screen while displaying video. Programs recorded in the original aspect ratio of film, which is proportionately wider than the aspect ratio of a computer or television monitor, will often appear with black bands above and below the viewing area. These bands are called the letterbox effect. The two formats whose framing shares a native aspect ratio of 16:9 are film and digital video. When high-definition television (HDTV) signals are viewed on a standard television tube with an approximate aspect ratio of 4:3, the letterbox effect results, unless a considerable amount of the picture is cropped from the sides.

letterbox effect