Anamorphic widescreen

Anamorphic widescreen is a video technique that utilizes rectangular (wide) pixels to store a widescreen picture into standard 4:3 aspect ratio. In its current understanding as a video term, it was originally devised for widescreen television sets with a 16:9 aspect ratio, however it has been used in regular film movies for decades. DVD using anamorphic widescreen are very similar to anamorphic film negatives, where the rectangular image is optically-squeezed (horizontally) to fit inside the almost-square storage space. When viewed on standard 4:3 televisions without adjustment, the anamorphic image will look compressed, such that the actors look exceptionally thin or tall (and a circle will appear as a vertical oval). Changing the DVD player's menu to the "4:3 letterbox" setting will digitally-insert black bars to the top/bottom of the image, thus eliminating the distortion and allowing the movie to be viewed in letterbox format. (Alternatively, the viewer can disconnect the 4:3 set... full article at wikipedia