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Anamorphic widescreen is a videographic process that horizontally squeezes a widescreen image so that it can be stored into a standard 4:3 aspect ratio DVD image frame. Compatible playback equipment can then re-expand the horizontal dimension to show the original widescreen image. In its current definition as a video term, it was originally devised for widescreen 16:9 aspect ratio television sets.

DVD Video

While DVD using anamorphic widescreen are conceptually similar to the anamorphic format used by film negative, the two formats are implemented with different techniques. In film, an anamorphic camera lens optically squeezes the image horizontally to fit a wide image onto the rectangular area of a standard 35mm film frame. The theater projectionist then uses another lens to un-squeeze the image on playback.

Anamorphic widescreen DVDs are also recorded using a horizontal-squeezing technique. If they are played on standard 4:3 television without adjustment, the anamorphic image will look horizontally squeezed; the actors will look thin and tall and a circle will be squashed to appear as a vertical oval. Changing the playback equipment to use the "fill" or "4:3 letterbox" setting will stretch the image horizontally to exactly reverse the squeezing used during recording. This allows the movie to be viewed in its original widescreen format. If the playback screen has a 4:3 physical format, typically black letterbox bars will be inserted above and below the image to fill the empty space. If the screen has a 16:9 physical format, stretching the image back to its original rectangle shape will typically fill the screen.

Most video DVDs include widescreen signaling to allow the player to automatically select whether the video should be horizontally stretched. If the source film's aspect ratio is wider than the standard 16:9 aspect ratio, then the DVD producer may choose to hard matte, or record narrow black bars above and below, the DVD's video to preserve the original artistic appearance of the film.

The DVD 720×480 standard was based upon the older analog NTSC and PAL standards which have a fixed 4:3 aspect ratio and tolerate a variable horizontal resolution (approximately 200 up to 700) depending upon the quality of the received signal. The DVD specification was designed to capture the highest detail of this variable horizontal resolution by assuming an ideal loss-less NTSC or PAL signal.

Describing the encoding of anamorphic DVDs is made somewhat more difficult because of the older analog formats that they depend on. While NTSC has approximately 720×480 visible pixels, these are non-square pixels (see the discussion under pixel aspect ratio) and so dividing the horizontal pixels by the vertical pixels does not result in the right aspect ratio. Similarly, PAL is approximately 720×576, but the pixels are again non-square (they are also rectangular but are different from NTSC pixels). Measuring the dimensions of a standard physical screens on which either NTSC or PAL/SECAM signals are displayed gives an aspect ratio of 4:3 (approximately 1.33). In DVD encoding, the "720×480" pixels do not imply that the DVD data is intended to be displayed using square pixels and an aspect ratio of 1.5:1; instead, a typical non-widescreen DVD encodes a 4:3 datasource into these 720×480 pixels with the assumption that they will be displayed in an NTSC fashion on a display with a physical 4:3 aspect ratio using non-square NTSC pixels. A widescreen DVD, on the other hand, anamorphically encodes a widescreen datasource (i.e. one with a large aspect ratio such as 1.85:1 or 2.35:1) by digitally compressing the visual information so that it will reside in the same 720×480 grid, but will be adjusted wider by the playback equipment for proper widescreen display.

Packaging

Pre-2001 MGM Anamorphic DVD Packaging Sample.
Pre-2004 Universal Anamorphic DVD Packaging Sample.
Now same graphic used by Sony Pictures Home Entertainment


DVDs with a 16:9 aspect ratio are typically labeled "Anamorphic Widescreen", "Enhanced for 16:9 televisions", "Enhanced for widescreen televisions", or similar, although currently there is no labeling standard. Otherwise, the movie will only support the standard full-frame display and will simply be letterboxed.

There has been no clear standardization for companies to follow regarding the advertisement of anamorphically enhanced widescreen DVDs. Some companies, such as Universal and Disney, include the aspect ratio of the movie. Below are how various companies advertise their anamorphic DVD movies on their packaging:

  • Anchor Bay: Enhanced for 16:9 TVs, includes aspect ratio in most cases.
  • Artisan Entertainment: 16:9 Fullscreen Version, or Enhanced for 16:9 Television (since it became part of Lions Gate, the newer reissues include aspect-ratio information on many titles). Note that this is a misuse of the term "fullscreen", which refers to a normal 4:3 ratio.
  • Buena Vista: Enhanced for 16:9 Televisions, includes aspect ratio.
  • Columbia TriStar: Anamorphic Video, sometimes not labeled, includes aspect ratio.
  • Criterion: Enhanced for Widescreen Televisions, or 16:9, always includes aspect ratio.
  • DreamWorksmarker: Widescreen format, enhanced for 16:9 televisions since acquisition by Paramount; aspect ratio included on formerly Universal-distributed titles.
  • Image Entertainment: Enhanced for 16:9 TVs, some titles include aspect ratio.
  • MGM: Enhanced for 16:9 TVs or Enhanced for Widescreen TVs, includes aspect ratio on 2001–present titles; uses Fox’s format since 2004.
  • New Line Cinema: Enhanced for Widescreen TVs.
  • Paramount Pictures: Enhanced for 16:9.
  • Trimark Pictures: Widescreen (letterboxed means non-anamorphic) Since it became part of Lions Gate, the newer reissues include aspect-ratio information on many titles.
  • 20th Century Fox: Enhanced for Widescreen TVs, Anamorphic Widescreen, sometimes not labeled, includes aspect ratio on newer titles.
  • Universal: Anamorphic Widescreen (widescreen means non-anamorphic) (Gives aspect ratio of film).
  • Warner Bros.: Enhanced for Widescreen TVs, says scope or matted instead of giving aspect ratio.


Film

Many commercial cinematic presentations (especially epics – usually with the CinemaScope 2.35:1 aspect ratio) are recorded onto standard 35 mm ~4:3 aspect ratio film , using an anamorphic lens to horizontally compress all footage into a ~4:3 frame. Another anamorphic lens on the movie theatre projector ultimately corrects (optically decompresses) the picture. See anamorphic format for details. Other movies (often with aspect ratios of 1.85:1 in the USA or 1.66:1 in Europe) are made using the simpler matte technique, which involves both filming and projecting without any expensive special lenses. The movie is produced in 1.375 format, and then the resulting image is simply cropped in post-production (or perhaps in the theater's projector) to fit the desired aspect ratio of 1.85:1 or 1.66:1 or whatever is desired. Besides costing less, the main advantage to the matte technique is that it leaves the studio with "real" footage (the areas that are cropped for the theatrical release) which can be used in preference to pan-and-scan when producing 4:3 DVD releases, for example.

The anamorphic encoding onto DVD is related to the anamorphic filming technique (aka Cinemascope) only by name. For instance, Star Wars (1977) was filmed in 2.35:1 ratio using an anamorphic camera lens, and shown in theaters using the corresponding projector lens. Since it is a widescreen film, when encoded to a widescreen-format DVD the studio would almost certainly use the anamorphic encoding process. Monty Python and the Holy Grail was filmed in 1.85:1 ratio without using an anamorphic lens on the camera, and similarly was shown in theaters without the need for the decompression lens. However, since it is also a widescreen film, when encoded to a widescreen-format DVD the studio would probably use the anamorphic encoding process.

It doesn't matter whether the filming was done using the anamorphic lens technique: as long as the source footage is intended to be widescreen, the digital anamorphic encoding procedure is appropriate for the DVD release. As a sidenote, if a purely-non-widescreen version of the analog-anamorphic Star Wars was to be released on DVD, the only options would be pan-and-scan or hardcoded 4:3 letterboxing (with the black letterboxes actually encoded as part of the DVD data). If you were to release a purely-non-widescreen version of Monty Python, you would have those options, as well as the additional option of an "open-matte" release, where the film footage that was never visible in theaters (due to use of the matte technique in post-production or in the theatrical projectors) is "restored" to the purely non-widescreen DVD release.

Television

Major digital television channel in Europe (for example, the five major UK terrestrial TV channels) carry anamorphic widescreen programming in standard definition. In almost all cases, 4:3 programming is also transmitted on the same channel. The SCART switching signal can be used by a set-top-box to inform the television which kind of programming (4:3 or anamorphic) is currently being received, so that the television can change modes appropriately. The user can often elect to display widescreen programming in a 4:3 letterbox format instead of pan and scan if they do not have a widescreen television.

TV stations and TV networks can also include Active Format Description (AFD) just as DVDs can. Many ATSC tuners (integrated or set-top box) can be set to respond to this, or to apply a user setting. This can sometimes be set on a per-channel basis, and often on a per-input basis, and usually easily with a button on the remote control. Unfortunately, tuners often fail to allow this on SDTV (480i-mode) channels, so that viewers are forced to view a small picture instead of cropping the unnecessary sides (which are outside of the safe area anyhow), or zooming to eliminate the windowboxing that may be causing a very tiny picture, or stretching/compressing to eliminate other format-conversion errors. The shrunken pictures are especially troublesome for smaller TV sets.

Many modern HDTV sets have the capability to detect black areas in any video signal, and to smoothly re-scale the picture independently in both directions (horizontal and vertical) so that it fills the screen. However, some sets are 16:10 (1.6:1) like a computer monitor, and will not crop the left and right edges of the picture, meaning that all programming looks slightly (though usually imperceptibly) tall and thin.

ATSC allows two anamorphic widescreen SDTV formats (interlaced and progressive scan) which are 704×480 (10% wider than 640×480), though it is unclear why this does not match the 720×480 of DVD. The format can also be used for fullscreen programming, and in this case it is anamorphic with pixels slightly taller (10:11, or 0.91:1) than their width.

See also



Notes

1. The standard 1932 Academy ratio changed the true aspect ratio of the image data to 1.375 when they made space for audio tracks, however, this is close enough to 4:3 that the difference is often glossed over.

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