Anamorph: Refers to the display process in which a widescreen image is distorted into a narrower format in order to obtain maximum image quality. During playback, this image is rectified again and a full-surface wide image is created. PAL For example, uses this technique to convert images in 4:3 format to 16:9 format. In order to avoid "eggheads", the image height is reduced in the same scale as the width, but this leaves black borders at the top and bottom.
