Also Known As: Letterboxed, Letterbox. As the aspect ratio of movies are rarely the same as the aspect ratio of a television screen, when showing movies on TV it is necessary to make sacrifices. "Letterboxing" is a video mastering process whereby a film source with an aspect ratio greater than that of the video master (4:3 for NTSC/PAL and 16:9 for HDTV) is transferred to the video master in such a way that no film image is cut off to the left or the right, requiring the addition of (usually) black bars at the top and at the bottom of the image so that it entirely fills the screen--in other words, the technique of shrinking the image just enough so that its entire width appears on screen, with black areas above and below the image. The advantage of this technique is that the film images are shown as originally intended by the film's creators, not interfering with their shot composition and artistic intentions. The disadvantage is that the entire image must be shrunk, which makes viewing on smaller TVs more difficult. Contrast with pan and scan (for DVD, also anamorphic widescreen).