Anamorphic widescreen

Anamorphic widescreen is a videographic technique utilising rectangular (wide) pixels to store a widescreen image to standard 4:3 aspect ratio. In its current definition as a video term, it originally was devised for widescreen 16:9 aspect ratio television sets; however, it has been used in regular film movies for decades.

DVD Video

DVDs using anamorphic widescreen are metaphorically similar to anamorphic format film negatives (although technically, the two formats are very different), wherein the rectangular image is optically-squeezed (horizontally) to fit inside the available negative area of standard filmstock. Anamorphic widescreen DVDs use a similar horizontal-squeezing technique to different purpose. When viewed on standard 4:3 televisions, without adjustment, the anamorphic DVD image will look compressed, such that the actors look exceptionally thin and tall (and a circle will appear as a vertical oval). Changing the DVD player's menu to the "4:3 letterbox" setting will digitally-insert black bars to the top/bottom of the image, thus eliminating the distortion and allowing the movie to be viewed in letterbox format. Alternatively, the viewer can replace the 4:3 television with a widescreen 16:9 television. The DVD needn't be changed, because the image is anamorphically encoded. However, the wider 16:9 screen will eliminate visual distortion and reduce or eliminate letterboxing.

Most video DVDs include a data marker that allows the player to automatically select whether the video should be presented with digitally-inserted black bars for 4:3 sets, or "as is" for 16:9 sets. If the source film is wider than the 16:9 (approximately 1.78:1) aspect ratio, then narrow black bars will be recorded on the top/bottom of the DVD's video, in order to preserve the proper appearance of the film (e.g. footage using as aspect ratio of 1.85:1 or 2.35:1 or whatever the director selected).

The DVD 720x480 standard was based upon the older analog NTSC and PAL standards which have a fixed 4:3 aspect ratio, but a variable horizontal resolution (approximately 200 up to 700) depending upon the quality of the received signal. The DVD specification was designed to capture this variable resolution, assuming an ideal lossless NTSC or PAL signal. Discussing the encoding of anamorphic DVD is somewhat difficult, because of the older analog formats which it depends upon. NTSC has approximately 720x480 visible pixels, but they are non-square pixels (see the discussion under pixel aspect ratio), so you cannot simply divide the horizontal resolution by the vertical resolution to get the aspect ratio. Similarly, PAL is approximately 720x576, but the pixels are again non-square (they are shaped rectangularly as well -- but in a different way than NTSC pixels). By measuring the dimensions of the physical screens on which both NTSC and PAL/SECAM signals are displayed, or alternatively by imagining perfectly square pixels in a grid of size 640x480, it turns out that the aspect ratio is 4:3 (approximately 1.33) when measured properly. To return to the DVD encoding, it is incorrect to say that the "720x480" pixels indicate that the DVD data has an aspect ratio of 1.5:1, because the pixels are (just like in NTSC) non-square.

A typical purely-non-widescreen DVD will (non-anamorphically) encode a 4:3 datasource into these 720x480 pixels with the assumption that they will be displayed in NTSC fashion on a display with a physical 4:3 aspect ratio, with the DVD player set in standard 4:3 viewing mode. Alternatively, a widescreen DVD will anamorphically encode 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 720x480 grid, but will appear to be in an optically distorted form when viewed under typical 4:3 NTSC/PAL/SECAM playback (again with the DVD player in standard 4:3 viewing mode). To view the compressed information properly on a 4:3 television, the DVD player can be placed into the 4:3 letterbox mode. To decompress the image data, the DVD player will shrink the image height appropriately (adding the black letterbox bars at the top and bottom of the 4:3 screen in the process). The benefit of the widescreen DVD is that you may load the same disc into a DVD player connected to a 16:9 television, put the DVD player into 16:9 mode, and "decompress" the anamorphic image data by spreading out the image width (grabbing the image by both ears and pulling outwards). If you stretched out a normal image that wasn't anamorphically encoded in this fashion, serious distortion would result, but because the image data was anamorphically encoded/compressed when the DVD was created, the stretching actually corrects the image data so that it faithfully reproduces the original cinematic format (including the correct aspect ratio). Note that a widescreen DVD doesn't mean that letterboxing will be entirely eliminated; this is only possible to accomplish without distortion when the original movie has an aspect ratio of 16:9. Movies that had an aspect ratio of 1.85:1 are very close to that number, however, and experience minimal letterboxing (less than 4% of the display height). Movies with 2.35:1 aspect ratios are further away from the 1.78:1 HDTV standard, which means that even when viewing the widescreen DVD there will still be clearly visible letterboxing.

Packaging

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:

*20th Century Fox: Enhanced for Widescreen TVs, Anamorphic Widescreen, sometimes not labeled, includes aspect ratio on newer titles.
*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).
*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.
*DreamWorks: 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.
*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 2.35:1 aspect ratio) are recorded onto standard 35mm ~4:3 aspect ratio film (accounting for the standard 1932 Academy ratio the true aspect ratio of the image data is actually 1.375 but this is close enough to 4:3 that the difference is often glossed over), 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 utilized in preference to pan-and-scan when producing 4:3 DVD releases, for example.

The essentially-digital anamorphic encoding onto DVD is only metaphorically related to the essentially-analog anamorphic filming technique (aka Cinemascope). 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 utilize 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 utilize the anamorphic encoding process. The point is that it doesn't matter whether the filming was done using the (analog) 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 channels in Europe (for example, the five major UK terrestrial 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.

ee also

* Anamorphosis
* Aspect ratio
* Letterbox
* Pan and scan

External links

* [http://www.dvdfile.com/news/special_report/production_a_z/anamorphic.htm Aspect ratios for DVD viewing]
* [http://www.thedigitalbits.com/articles/anamorphic/anamorphic185demo.html Anamorphic vs. Non-Anamorphic DVD]
* [http://gregl.net/videophile/anamorphic.htm World's Easiest Explanation of Anamorphic 16:9 Widescreen Enhancement]