Open matte is a filming technique that involves matting out the top and bottom of the film frame in the movie projector (known as a soft matte) for the widescreen theatrical release and then scanning the film without a matte (at Academy ratio) for a full screen home video release.
Usually, non-anamorphic 4-perf films are filmed directly on the entire full frame silent aperture gate (1.33:1). When a married print is created, this frame is slightly re-cropped by the frame line and optical soundtrack down to Academy ratio (1.37:1). The movie projector then uses an aperture mask to soft matte the Academy frame to the intended aspect ratio (1.85:1 or 1.66:1). When the 4:3 full-screen video master is created, many filmmakers may prefer to use the full Academy frame ("open matte") instead of creating a pan and scan version from within the 1.85 framing. Because the framing is increased vertically in the open matte process, the decision to use it needs to be made prior to shooting, so that the camera operator can frame for 1.85:1 and "protect" for 4:3; otherwise unintended objects such as boom microphones, cables, and light stands may appear in the open matte frame, thus requiring some amount of pan and scan in some or all scenes. Additionally, the un-matted 4:3 version will often throw off an otherwise tightly-framed shot and add an inordinate amount of headroom above actors (particularly with 1.85:1).
Open-matte doesn't happen as often with most films that are presented in 2.20:1 or 2.39:1. Instead those employ pan and scan or reframing using the well-protected areas. Many films over the years have used this technique, the most prominent of which include Back to the Future, Schindler's List, Titanic, and Top Gun as well as many films that have been specially formatted for the IMAX expanded aspect ratio of 1.90:1. Stanley Kubrick also used this technique for his last three films The Shining (1980), Full Metal Jacket (1987) and Eyes Wide Shut (1999).) James Cameron's Terminator 2: Judgment Day (1991) is also an example of open-matte.
The rise new film exhibition technologies in 1950s like Cinerama, and anamorphic lenses, shooting wide aspect ratios for theatrical films. This coincided with the rise of television and home media with a much different, narrow aspect ratio of 4:3. To avoid letterboxing for broadcast releases, films were therefore reframed and cropped shot by shot to fit appropriately, and full screen with the 4:3 aspect, with a process called Pan and Scan. Hence, only a cropped small portion of the theatrical frame was broadcast.
Difference between Open Matte and Pan and ScanEdit
Pan and Scan deals with only the 2.39:1 master of a film. For HDTV, the sides are cropped to fit the 16:9 frame.
If footage with taller ratios were shot (digitally or on film), for example IMAX scenes for various films, then the screen real-estate is cropped in accordance to the deliverable ratio. This helps in preserving headroom and composition for the film beyond the theatrical release.
Open matte on LaserDisc is very confusing and is typically explained by YouTube film expert Sam Hatch, colloquially known as CultureDog. Sam Hatch is frequently annoyed by the misuse of the term "Open Matte" and has made it his personal mission to educate and inform new LaserDisc collector's about the proper use of the term. Sam Hatch has been the world's foremost LaserDisc collector and archivist for 20+ years.