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Aspect Ratio

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For other uses see Aspect Ratio (disambiguation).

The Aspect Ratio of an Image is its displayed width divided by its height (usually expressed as "x:y"). For instance, the aspect ratio of a traditional television screen is 4:3, or 1.33:1. High definition television uses an aspect of 16:9, or about 1.78:1. Aspect ratios of 2.39:1<ref name="anamorphic">NOTE: The 2.39:1 ratio is more commonly referred to as 2.40:1. The ratio was 2.35:1 prior to SMPTE revision in 1970, and is still often mistakenly referred to as 2.35:1 although only anamorphic films photographed prior to 1970 are in the 2.35:1 aspect ratio. The American Society of Cinematographers' American Cinematographer Manual uses only 2.40:1 not 2.39:1.</ref> or 1.85:1 are frequently used in cinematography, while the aspect ratio of a sync-sound 35 mm film frame is 1.37:1 (also known as "Academy Aperture" ratio). Silent films, which used the full frame, were shot in 1.33:1.

Contents

The evolution of film and TV aspect ratios

Comparison of three common aspect ratios constrained by the screen diagonal size (the black circle). The smaller box (blue) and middle box (green) are common formats for cinematography. The largest box (red) is the format used in standard television.
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Comparison of three common aspect ratios constrained by the screen diagonal size (the black circle). The smaller box (blue) and middle box (green) are common formats for cinematography. The largest box (red) is the format used in standard television.

The 4:3 ratio for standard television has been in use since television's origins and many computer monitors use the same aspect ratio. Since 4:3 is the aspect ratio defined by the Academy of Motion Picture Arts and Sciences as a standard after the advent of optical sound-on-film. Matching this aspect ratio meant that films previously photographed on film could be satisfactorily viewed on TV in the early days of the medium. When cinema attendance dropped, Hollywood created widescreen aspect ratios to immerse the viewer in a more realistic experience and, possibly, to make the cinema experience more of a spectacle that could not be achieved at home on a regular TV set.

16:9 is the international standard format of HDTV as used in Australia, Japan and America, as well as in Europe on satellite and non-HD widescreen television (EDTV) PAL-plus. Japan's Hi-Vision originally started with a 5:3 ratio but converted when the international standards group introduced a wider ratio of 5⅓ to 3 (=16:9). Many digital video cameras have the capability to record in 16:9. Anamorphic DVD transfers store the information in 16:9 vertically stretched to 4:3; if the TV can handle an anamorphic image the signal will be de-anamorphosed by the TV to 16:9. If not, the DVD player will unstretch the image and add letterboxing before sending the image to the TV. Wider ratios such as 1.85:1 and 2.40:1<ref name="anamorphic" /> are accommodated within the 16:9 DVD frame by adding some additional masking within the image itself.

Within the motion picture industry, the convention is to assign a value of 1 to the image height, so that, for example, an anamorphic frame is described as 2.40:1 or just "2.40" (pronounced "two four oh"). The most common projection ratios in American theaters are 1.85:1 and 2.40:1. Some European countries use 1.66:1 as a widescreen standard. 1.33:1 was used for all theatrical films up until the 1950s when 1.85:1 became the standard for US theatrical projection. The size of the image in motion picture formats is dictated by the physical size of the film area between the perforations. The universal standard, as established by William Dickson and Thomas Edison in 1892, is a frame that is four perforations high. The film itself is 35 mm wide (1.38 in), but the area between the perforations is 24.89 mm by 18.67 mm (.980 in by .735 in)<ref name="asc">Burum, Stephen H. (ed) (2004). American Cinematographer Manual (9th ed). ASC Press. ISBN 0-935578-24-2</ref>. With a space designated for the standard optical soundtrack, and the frame size reduced to maintain a picture that was wider than taller (more mimicing human vision), this resulted in the Academy aperture of 22 mm by 16 mm (.866 in by .630 in) or 1.37:1.

Development of various camera systems must therefore ultimately cater to the placement of the frame in relation to these lateral constraints of the perforations and the optical soundtrack area. One clever widescreen alternative, VistaVision, used standard 35 mm film running sideways through camera gate, so that the sprocket holes were above and below frame, resulting in a larger horizontal negative size per frame as the vertical size was now restricted by the peforations. However, the 1.5 ratio of the initial VistaVision image needed to be cropped down to 1.85 and optically converted to a vertical print (on standard 4-perforation 35 mm film) for projection. Though the format was briefly revived by Lucasfilm in the 1970s for special effects work that required larger negative size due to image degradation from the optical printing steps necessary to make multi-layer composites, it went into obsolescence largely due to better cameras, lenses, and film stocks available to standard 4-perforation formats, in addition to increased lab costs of making prints in comparison to more standard vertical processes. (The horizontal process was later adapted to 70 mm film by IMAX.)

Super 16 mm film is frequently used for television production due to its lower cost, lack of need for soundtrack space on the film itself (as it is not projected but rather transferred to video), and aspect ratio similar to 16:9 (Super 16 mm is natively 1.66 whilst 16:9 is 1.78). It also can be blown up to 35 mm for theatrical release and therefore is also used for feature films.

Visual comparisons

Two aspect ratios compared with images using the same horizontal size.
4:3 (1.33:1)
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16:9 (1.78:1)
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Two aspect ratios compared with images using the same vertical size.
4:3 (1.33:1)
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16:9 (1.78:1)
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Comparisons of computer display resolutions.
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Comparisons of computer display resolutions.

Historic and commonly used aspect ratios

See List of film formats for a full listing of film formats, including their aspect ratios.
  • 1.19:1: "Movietone" - early 35 mm sound film ratio used in the late 1920s and early 1930s, especially in Europe. The optical soundtrack was placed on the side of the 1.33 frame, thus reducing the width of the frame. The Academy Aperture frame (1.37) fixed this by making the frame lines thicker. The best examples of this ratio are Fritz Lang's first sound films: M and The Testament of Dr. Mabuse. This is roughly the frame size used for anamorphic photography today.
  • 1.25:1: Commonly used computer resolution of 1280x1024. Native aspect ratio of many LCDs. Also the aspect ratio of 4x5 film photos. The British 405 line TV system used this aspect ratio from its beginning in the 1930s until 1950 when it changed to the more common 4:3 format.
  • 1.33:1: 35 mm original silent film ratio, common in TV and video as 4:3. Also standard ratio for IMAX and MPEG-2 video compression.
  • 1.37:1: 35 mm full-screen sound film image, nearly universal in movies between 1932 and 1953. Officially adopted as the Academy ratio in 1932 by AMPAS. Still occasionally used. Also standard 16 mm.
  • 1.43:1: IMAX 70 mm horizontal format.
  • 1.5:1: The aspect ratio of 35 mm film used for still photography. Wide-aspect computer display (3:2). Used in Apple PowerBook G4 15.2" displays with resolutions of most recently 1440x960. Also the native NTSC DVD-Video resolution, 720x480, although most videos use non-square pixels for a 4:3 ratio.
  • 1.56:1: Widescreen aspect ratio 14:9. Often used in shooting commercials etc. as a compromise format between TV 4:3 (12:9) and Widescreen 16:9, especially when the output will be used in both standard tv and widescreen. When converted to a 16:9 frame, only a small portion of the picture is lost, and when converted to 4:3 there is only slight letterboxing.
  • 1.6:1: computer display widescreen (8:5, commonly referred to as 16:10). Used in WSXGAPlus, WUXGA and other display resolutions. Historically also the aspect ratio of CGA (320×200).
  • 1.66:1: 35 mm European widescreen standard; Super 16 mm. (5:3, sometimes expressed more accurately as "1.67".)
  • 1.75:1: early 35 mm widescreen ratio, since abandoned.
  • 1.78:1: video widescreen standard (16:9). Also used in high-definition television One of 3 ratios specified for MPEG-2 video compression.
  • 1.85:1: 35 mm US and UK widescreen standard for theatrical film. Uses approximately 3 perforations ("perfs") of image space per 4 perf frame; films can be shot in 3-perf to save cost of film stock. Also known as "flat".
  • 2.2:1: 70 mm standard. Originally developed for Todd-AO in the 1950s. 2.21:1 specified for MPEG-2 but not used.
  • 2.35:1 : 35 mm anamorphic prior to 1970, used by CinemaScope ("'Scope") and early Panavision. The anamorphic standard has subtly changed so that modern anamorphic productions are actually 2.39<ref name="anamorphic" />, but often referred to as 2.35 anyway, due to old convention. No recent anamorphic films are 2.35. (Note that anamorphic refers to the print and not necessarily the negative.)
  • 2.39:1: 35 mm anamorphic from 1970 onwards. Sometimes rounded up to 2.40<ref name="anamorphic" />. Sometimes referred to as 'Scope.
  • 2.55:1: Original aspect ratio of CinemaScope before optical sound was added to the film. This was also the aspect ratio of CinemaScope 55.
  • 2.59:1: Cinerama at full height (three specially captured 35 mm images projected side-by-side into one composite widescreen image).
  • 2.76:1: MGM Camera 65 (65 mm with 1.25x anamorphic squeeze). Only used on a handful of films between 1956 and 1964, such as Ben-Hur (1959).
  • 4:1: Polyvision, three 35 mm 1.33 images projected side by side. Only used on Abel Gance's Napoléon (1927).

Aspect ratio releases

Original aspect ratio (OAR)

Original Aspect Ratio (OAR) is a home cinema term for the aspect ratio or dimensions in which a film or visual production was produced — as envisioned by the people involved in the creation of the work. As an example, the film Gladiator was released to theaters in the 2.40:1 aspect ratio. It was filmed in Super 35 mm film and, in addition to being presented in cinemas and television in the Original Aspect Ratio of 2.40:1, it was also broadcast without the matte altering the aspect ratio to the television standard of 1.33:1.

Modified aspect ratio (MAR)

Modified Aspect Ratio is a home cinema term for the aspect ratio or dimensions in which a film was modified to fit a specific type of screen, as opposed to original aspect ratio. Modified aspect ratios are usually either 1.33:1 (historically), or (with the advent of widescreen television sets) 1.78:1 aspect ratio. 1.33:1 is the modified aspect ratio used historically in VHS format. A modified aspect ratio transfer is achieved by means of pan and scan or open matte, the latter meaning removing the cinematic matte from a 1.85:1 film to open up the full 1.33:1 frame.

Criticism

Multiple aspect ratios create additional burdens on filmmakers, consumers and confusion among TV broadcasters. It is not uncommon for a widescreen film to be presented in an altered format (cropped or expanded beyond the Original Aspect Ratio). It is also not uncommon for a 16:9 broadcast to embed a 4:3 commercial within the 16:9 image area. A viewer watching on a standard 4:3 (non-widescreen) television would see an 4:3 image of the commercial with 2 sets of black stripes, vertical and horizontal (matchboxing). A similar scenario may also occur for a widescreen set owner when viewing 16:9 material embedded in a 4:3 frame. It is also not uncommon that a 4:3 image is stretched horizontally to fit a 16:9 screen and avoid pillarboxing.

For many artists, however, aspect ratio is determined not by the constraints of the technology or medium, but by the content or the story. Indeed, as long ago as the early 20th century, film directors such as D. W. Griffith, one of the early giants in film, would sometimes change the picture aspect ratio within the film. In "Intolerance", for example, a single shot where a character falls from a high wall has the sides of the vista greatly cropped to enhance the dramatic height of the fall. Today, Directors of Photography are often forced to compose the shot to keep the essential subjects in the "sweet spot" of the frame as a compositional compromise between the intended aspect ratio and the potenial furture alternate ratios to be presented.

References

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See also

External links

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