|Comparison of three common aspect ratios. The outer box (blue) and middle box (red) are common formats for cinematography. The inner box (green) is the format used in standard television.|
Comparison of three common aspect ratios. The outer box (blue) and middle box (red) are common formats for cinematography. The inner box (green) is the format used in standard television.Within the motion picture industry, the convention is to assign a value of 1 to the image height, so that, for example, a Cinemascope frame is described as 2.35:1 or just "2.35". This way of speaking comes about because the width of a film image is restricted by the presence of sprocket holes and, usually, an optical sound track on the projection print. Development of various camera systems therefore centers on the placement of the frame in relation to these lateral constraints; the height of image can be adjusted freely, so the ingenuity goes into getting different widths. One clever widescreen process, VistaVision, used standard 35mm film running sideways through camera gate, so that the sprocket holes were above and below frame and the width was not restricted. The most common projection ratios in American theaters are 1.85 and 2.35.
The term is also used in the context of computer graphics to describe the shape of an individual pixel in a digitized image. Most digital imaging systems use square pixels--that is, they sample an image at the same resolution horizontally and vertically. But there are some devices that do not, so a digital image scanned at twice the horizontal resolution to its vertical resolution might be described as being sampled at a 2:1 aspect ratio, regardless of the size or shape of the image as a whole.
WidescreenA widescreen image is a film image with a greater aspect ratio than the ordinary 35 millimeter frame.
The aspect ratio of a standard 35 millimeter frame is around 1.37:1, although cameramen may use only the part of the frame which will be visible on a television screen (which is 1.33:1 for standard television). Viewfinders are typically inscribed with a number of frame guides, for various ratios.
Note that aspect ratio refers here to the projected image. There are various ways of producing a widescreen image of any given proportion.
- Anamorphic: used by Cinemascope, Panavision and others. Anamorphic camera lenses compress the image horizontally so that it fits a standard frame, and anamorphic projection lenses restore the image and spread it over the wide screen. The picture quality is reduced because the image is stretched to twice the original area, but improvements in film and lenses have made this less noticeable.
- Masked: the film is shot in standard ratio, but the top and bottom of the picture are masked off by mattes in the projector. Alternatively, a hard matte in the camera may be used to mask off those areas while filming. Once again the picture quality is reduced because only part of the image is being expanded to full height. Sometimes films are designed to be shown in cinemas in masked widescreen format but the full unmasked frame is used for television. A low-budget movie called Secret File: Hollywood, often ridiculed as a collection of bloopers, is actually an example of a film that is always projected wrong. All the lights and microphone booms visible above the actors should be concealed by a projection matte, creating an image that would fill a wide screen for little money.
- Multiple camera/projector: the Cinerama system originally involved shooting with three synchronized cameras locked together side by side, and projecting the three resulting films on a curved screen with three synchronized projectors. Later Cinerama movies were shot in super anamorphic (see below), and the resultant widescreen image was divided into three by optical printer lenses to produce the final threefold prints. The technical drawbacks of Cinerama are discussed in its own article.
- Big film format: a 70mm film frame is not only twice as wide as a standard frame but also has greater height. Shooting and projecting a film in 70mm therefore gives more than twice the image area of non-anamorphic 35mm film with no loss of quality.
- Super anamorphic: 70mm with anamorphic lenses creates an even wider high-quality picture.
LetterboxLetterboxing is the practice of copying widescreen film to video formats while preserving the original aspect ratio. Since the video display is most often a more square aspect ratio than the original film, the resulting master must include masked-off areas above and below the picture area (these are often referred to as "black bars", resembling a letterbox slot). The term takes its name from the similarity of the resulting image to a horizontal opening in a postal letter box. The resulting video master utilizes only a portion of the display screen, the technique offers an alternative to the older pan and scan method of copying that cropped the image to suit the 4:3 (or 12:9) ratio of the television screen and preserves the original composition of the film as seen in the theater.
Some filmmakers state a preference for letterboxed videos of their work. Woody Allen's insistence on a letterboxed release of Manhattan probably inspired this treatment of other films. One exception to the preference is Milos Forman, who finds the bands distracting. However, most video releases are made without consultation with either the director or director of cinematography of the film. The letterboxing is often careless, and the common 16:9 ratio does not precisely correspond to aspect ratios of the most common widescreen systems.
HDTV, a newer digital video system, uses video displays with a wider aspect ratio than standard television and, is becoming the broadcast standard in the United States. The wider screen will make it easier to make an accurate letterbox transfer. Some contemporary television programming is being produced in letterbox format. This is done both to give a "classier" look to the image (particularly in the case of advertising), and to facilitate the production of widescreen programming for later syndication in HDTV.
16:9 widescreen television is also becoming common on European digital television systems. Although this is not true HDTV it uses the same aspect ratio, and the majority of programming in countries like Britain and France is now made in letterbox format. Of course, on a true widescreen television set the "letterboxed" 16:9 picture is no longer letterboxed since it fills the entire screen. However, movies made in even wider aspect ratios are letterboxed to some extent even on 16:9 sets.
Sometimes, by accident or design, a standard-ratio image is presented in the central portion of a letterboxed picture, resulting in a black border all around. This is referred to as "matchboxing" and is generally disliked because it wastes a lot of screen space and reduces the resolution of the original image. This can for instance be seen on some of the DVD editions of the Star Trek movies whenever the widescreen documentaries included as extras use footage from the original TV series. The alternative would be to crop the original 4:3 TV images horizontally to fit the 16:9 ratio.
Pan and ScanPan and scan is a method of adjusting widescreen film images so that they can be shown within the proportions of an ordinary video screen.
Until High Definition Television came onto the scene, television images had approximately the shape of a frame of 35mm film: a width 1.33 times the height (in the industry, referred to as "4:3 aspect ratio"). By contrast, a film image typically has a more rectangular final projected image with an aspect ratio greater than 16:9, often as wide as 2.35 times the height of the image. To broadcast a widescreen film on television, or create a videotape or DVD master it is necessary to make a new version from the original filmed elements. One way to do so is to make a "letterbox" print, which preserves the original theatrical aspect ratio, but produces an image with black bars at the top and bottom of the screen. Another way to turn the 16:9 aspect ratio film into a 4:3 aspect ratio television image is to "pan and scan" the negative.
During the "pan and scan" process, an operator selects the parts of the original filmed composition that seem to be significant and makes sure they are copied"scanning." When the important action shifts to a new position in the frame, the operator moves the scanner to follow it, creating the effect of a pan shot.
This method allows the maximum resolution of the image, since it uses all the available video scan lines. It also gives a full-screen image on analog television. But it can also severely alter compositions and therefore dramatic effectsfor instance, in the film Jaws, the shark can be seen approaching for several seconds more in the widescreen version than in the pan and scan version. In some cases, the results can also be a bit jarring, especially in shots with significant detail on both sides of the frame: the operator must either go to a two-shot format (alternating between closeups in what was previously a single image), lose some of the image, or make several abrupt pans. In cases where a film director has carefully designed his composition for optimal viewing on a wide theatrical screen, these changes may be seen as changing that director's vision to an unacceptable extent.
Once television revenues became important to the success of theatrical films, cameramen began to work for compositions that would keep the vital information within the "TV safe area" of the frame. For example, the BBC suggests program producers frame their shots in a 14:9 aspect ratio to minimize the effects of converting film to television. In other cases film directors reverse this process, creating a negative with information that extends above and below the widescreen theatrical image (this is sometimes referred to as a "full frame" composition). Often pan-and-scan compositors make use of this full-screen negative as a starting point, so that in some scenes the TV version may contain more image content than the widescreen version while in other scenes where such an "opened" composition is not appropriate a subset of the widescreen image may be selected. In some cases (notably many of the films of Stanley Kubrick) the original 1.33:1 aspect ratio of the negative is transferred directly to the video master (although these versions also represent a new aspect ratio compared to the original theatrical release these are not properly "pan and scan" transfers at all but are often called "full-frame" or "open matte" transfers).
Yet some directors still balk at the use of "pan and scan" version of their movies; for instance Steven Spielberg initially refused to release a pan and scan version of Raiders of the Lost Ark, but eventually gave in; Woody Allen refused altogether to release one of Manhattan and the letterboxed version is in fact the only version available on VHS and DVD.
CinemaScopeCinemascope, or more strictly CinemaScope, was a widescreen movie format used in the US from 1953 to 1967. Using anamorphic lenses and 35 mm film it could project film at a 2.66:1 ratio, twice as wide as conventional lenses could achieve.
It was developed by 20th Century Fox to supplant the complex, multi-projector Cinerama process, first shown in 1952. The actual anamorphic process, initially called Anamorphoscope, was developed by Henri Chétien around 1927 using lenses he called hypergonar. Chétien had been attempting to sell his process to Hollywood since the 1930s but with little interest, until the advent of Cinerama. Another factor was the rise of television, which meant that the studios saw the need for a spectacle to compete.
The hypergonar lens patents were acquired by 20th Century Fox in 1952 and the system was renamed Fox CinemaScope. The advantage over Cinerama was that all the system needed was an additional lens unit fitted to the front of ordinary cameras and projectors, although stereo sound could be carried on separate 35mm tracks. It was first demonstrated in 1953 and the first film shot was The Robe (September 1953). The technology was licensed by Fox to MGM and Disney and shortly afterwards to Columbia, Universal and Warner. However, initial uncertainty meant that a number of films were shot simultaneously with anamorphic and regular lenses. Also only the 'biggest' films were made in Cinemascope, around a third of the total produced.
Although Cinemascope was capable of producing a 2.66:1 image, the addition of stereo information could reduce this to 2.55:1. A change in the base 35 mm film aperture eventually reduced Cinemascope to 2.35:1. Often cinemas with smaller screens would further crop the format to make it fit. A general problem with expanding the visible image meant that there could be visible grainyness and brightness problems, so to combat this larger formats were developed; initially an unsuccessful 55 mm, and later 65 and 70 mm.
Since the actual anamorphic process was not patentable (it had been known for centuries and had been used in paintings such as "The Ambassadors" by Hans Holbein), some studios sought to develop their own systems rather than pay Fox - RKO used Superscope, Republic used Naturama, Warner developed Warnerscope. Other systems developed included Panatar, Vistarama, Technovision and Euroscope. Cinemascope itself was called Regalscope when used by the Fox adjunct Regal Films for black-and-white features.
Many US studios adopted the cheaper, non-Fox, but still anamorphic Panavision system and by the mid-1960s even Fox had abandoned Cinemascope for Panavision. The initial problems with grain and contrast were eventually solved thanks to improvements in film stock and lenses.