Matte (filmmaking)

Mattes are used in photography and filmmaking to insert part of a foreground image onto a background image, which is often a matte painting, a background filmed by the second unit, or computer generated imagery. In modern use, the foreground element is often also computer generated.

The original technique was to shoot an actor on a small set through a hole in a sheet of transparent glass or plastic plate bearing a painted background. The camera would be carefully positioned so that the background painted on the plate would appear to blend with the set as seen from the camera, giving the impression that the actor was in a large space without having to actually build that space. A similar effect, using models and a mirror, is called the Schüfftan process.

A later development, called the travelling matte, allowed the shape and position of the matte to be altered from frame to frame, enabling greater freedom of composition and movement as the actors did not have to remain within a set portion of the image. If the matte were made exactly the same size and shape as the image of the actor, it was even possible to replace the entire background.

Bluescreen techniques, originally invented by Petro Vlahos as a film optical process, are commonly used to extract travelling mattes without using either rotoscoping or multiple motion control passes. Bluescreens are now commonly generated entirely digitally, as part of a digital compositing process.

Mattes and Widescreen Filming

Another use of mattes in filmmaking is to create a widescreen effect. In this process, the top and bottom of a standard frame are matted out, or masked, with black bars, i.e. the film print has a thick frame line. Then the frame within the full frame is enlarged to fill a screen when projected in a theater.

Thus, in "masked widescreen" an image with an aspect ratio of 1.85:1 is created by using a standard, 1.33:1 frame and matting out the top and bottom. If the image is matted during the filming process it is called a "hard matte." In contrast, if the full frame is filled during filming and the projectionist is relied upon to matte out the top and bottom in the theater, it is referred to as a "soft matte."

In video, a similar effect is often used to present widescreen films on a conventional, 1.33:1 television screen. In this case, the process is called letterboxing.

See also

• Compositing
• In-camera effect
• Bipack
• Difference matte
• Gash matte
• Widescreen
• Anamorphic widescreen