See mask.

A portion of the screen which is blackened or otherwise covered to change the aspect ratio of an image being presented on a monitor or television screen. A matte is typically applied to the top and bottom of the screen when using the letterbox format in DVD-Video playback.

(also mask): Early filmmakers created in-camera composites by covering part of the lens with a mask while filming, or placing a sheet of glass with a blacked-out area between the camera and the scene, to prevent a portion of the film from being exposed. The cameraman would then rewind the film, and shoot again with the mask removed and the previously exposed area covered, thus combining two images in one shot. In "The Playhouse," (1921), Buster Keaton used this method to put himself on-stage as nine different characters. A stationary matte marks off a static defined area; a travelling matte follows the silhouette of a moving character or object and changes shape from frame to frame.

A mask layer is sometimes called a matta or alpha matte. Commonly used to make a certain colour background transparent.

A means of covering up part of an image. In motion picture photography and video it (as plural) generally refers to the aperture plates or other means of hiding from view the top and bottom edges, leaving what will ultimately be a wide screen movie picture. Whereas without the mattes the displayed image would be taller with extra material at the top and bottom that is really not part of the presentation.

The process of using an electronic mask to cover part of a video image and replace it with another image.

store matte channel if the image has one

In rendering, information that defines the transparency of each pixel (opaque, partly transparent, completely transparent). The unused pixels of an image (black space) have a completely transparent matte.

A separate [usually] black and white signal that is used to separate parts of the image during compositing.

The black bars used to change a screen’s ratio from standard TV (4:3) to widescreen (16:9).

Mattes are used in photography and special effects filmmaking to combine two or more image elements into a single, final image. Usually, mattes are used to combine a foreground image (such as actors on a set, or a spaceship) with a background image (a scenic vista, a field of stars and planets).