|Five common aspect ratios|
The aspect ratio of an image is the ratio of the width of the image to its height, expressed as two numbers separated by a colon. That is, for an x:y aspect ratio, no matter how big or small the image is, if the width is divided into x units of equal length and the height is measured using this same length unit, the height will be measured to be y units. For example, consider a group of images, all with an aspect ratio of 16:9. One image is 16 inches wide and 9 inches high. Another image is 16 centimeters wide and 9 centimeters high. A third is 8 yards wide and 4.5 yards high.
Aspect ratios are mathematically expressed as x:y (pronounced "x-to-y") and x×y (pronounced "x-by-y"). The most common aspect ratios used today in the presentation of films in movie theaters are 1.85:1 and 2.39:1. Two common videographic aspect ratios are 4:3 (1.33:1), universal for standard-definition video formats, and 16:9 (1.78:1), universal to high-definition television and European digital television. Other cinema and video aspect ratios exist, but are used infrequently. In still camera photography, the most common aspect ratios are 4:3, 3:2, and more recently being found in consumer cameras, previously only commonly seen in professional cameras, 16:9. Other aspect ratios, such as 5:4, 6:7, and 1:1 (square format), are used in photography as well.
With television, DVD and Blu-ray, converting formats of unequal ratios is achieved by either: enlarging the original image to fill the receiving format's display area and cutting off any excess picture information (zooming and cropping), by adding horizontal mattes (letterboxing) or vertical mattes (pillarboxing) to retain the original format's aspect ratio, or (for TV and DVD) by stretching (and sometimes distorting) the image to fill the receiving format's ratio. Cinematographic aspect ratios are usually denoted as a decimal multiple of width vs unit height, whilst videographic aspect ratios are usually defined and denoted by whole number ratios of width to height.
In motion picture formats, the physical size of the film area between the sprocket perforations determines the image's size. The universal standard (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×18.67 mm (0.980 in×0.735 in), leaving the de facto ratio of 4:3, or 1.33:1.
With a space designated for the standard optical soundtrack, and the frame size reduced to maintain an image that is wider than taller (mimicking human eyesight), this resulted in the Academy aperture of 22 mm × 16 mm (0.866 in × 0.630 in) or 1.37:1 aspect ratio.
The motion picture industry convention assigns a value of 1.0 to the image’s height; thus, an anamorphic frame (actually 2.39:1) is described (rounded) as 2.40:1 or 2.40 ("two-four-oh"). In American cinemas, the common projection ratios are 1.85:1 and 2.40:1. Some European countries have 1.66:1 as the wide screen standard. The "Academy ratio" of 1.37:1 was used for all cinema films until 1953 (with the release of George Stevens's Shane). During that time, television, which had a similar aspect ratio of 1.33:1, became a threat to movie audiences, Hollywood gave birth to a large number of wide-screen formats: CinemaScope, Todd-AO, and VistaVision to name just a few. The "flat" 1.85:1 aspect ratio was introduced in May, 1953, and became one of the most common cinema projection standards in the U.S. and elsewhere.
Development of various film camera systems must ultimately cater to the placement of the frame in relation to the lateral constraints of the perforations and the optical soundtrack area. One clever wide screen alternative, VistaVision, used standard 35 mm film running sideways through the camera gate, so that the sprocket holes were above and below frame, allowing a larger horizontal negative size per frame as only the vertical size was now restricted by the perforations. However, the 1.50:1 ratio of the initial VistaVision image was optically converted to a vertical print (on standard 4-perforation 35 mm film) to show in the projectors available at theaters, and was then masked in the projector to the US standard of 1.85:1. 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 (the native ratio of Super 16 mm 1.66:1 while 16:9 is 1.78:1). It also can be blown up to 35 mm for theatrical release and therefore is also used for feature films.
The 4:3 ratio (generally named as "Four-Three", "Four-by-Three", "Four-to-Three", or "Academy Ratio") for standard television has been in use since television's origins and many computer monitors use the same aspect ratio. 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. By having TV match this aspect ratio, films previously photographed on film could be satisfactorily viewed on TV in the early days of the medium (i.e. the 1940s and the 1950s). When cinema attendance dropped, Hollywood created widescreen aspect ratios (such as the 1.85:1 ratio mentioned earlier) in order to differentiate the film industry from TV.
16:9 (generally pronounced as "Sixteen-by-Nine"; alternates include "Sixteen-Nine" and "Sixteen-to-Nine") is the international standard format of HDTV, non-HD digital television and analog widescreen television (EDTV) PALplus. 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 transfers onto DVD horizontally squeeze the original widescreen image to store the information into a 4:3 aspect ratio DVD frame. If the TV has a feature to un-squeeze an anamorphic image, it will horizontally decompress the image to 16:9. If not, many DVD players can also reduce scan lines and add letterboxing bars above and below the image before sending it to the TV. This is made easier by the simple 4:3 aspect ratio between 4:3 and 16:9 (16:9 = 4:3 × 4:3). DVD producers can also choose to show even wider ratios such as 1.85:1 and 2.39:1 within the 16:9 DVD frame by hard matting or adding black bars within the image itself. Some films which were made in a 1.85:1 aspect ratio, such as the U.S.-Italian co-production Man of La Mancha, fit quite comfortably onto a 1.78:1 HDTV screen and have been issued anamorphically enhanced on DVD without the black bars. Note that, in order for this to work, the 'pixels' are assumed to not be square; but have a 1:1.094 ratio .
When the 16:9 aspect ratio was proposed by Dr. Kerns H. Powers, a member of the SMPTE Working Group On High-Definition Electronic Production, nobody was creating 16:9 videos. The popular choices in 1980 were: 4:3 (based on television standard's ratio at the time), 1.66:1 (the European "flat" ratio), 1.85:1 (the American "flat" ratio), 2.20:1 (the ratio of 70 mm films and Panavision) and 2.35:1 (the CinemaScope ratio for anamorphic widescreen films). Dr. Powers cut out rectangles with equal areas and shaped them to match each of the popular aspect ratios. When overlapped with their center points aligned, he found that all of those aspect ratio rectangles fit within an outer rectangle with an aspect ratio of 1.78:1 and all of them also covered a smaller common inner rectangle with the same aspect ratio 1.78:1. The geometric mean of the extreme aspect ratios, 4:3 (1.33:1) and 2.35:1, is also 1.77:1 which is coincidentally close to 16:9 (1.78:1).
While 16:9 (1.78:1) was initially selected as a compromise format, the subsequent popularity of HDTV broadcast has solidified 16:9 as perhaps the most important video aspect ratio for the future. Most 4:3 (1.33:1) and 2.39:1 video is now recorded using a "shoot and protect" technique that keeps the main action within a 16:9 (1.78:1) inner rectangle to facilitate HD broadcast.. Conversely it is quite common to use a technique known as center-cutting, to approach the challenge of presenting material shot (typically 16:9) to both a HD and legacy 4:3 audience simultaneously without having to compromise image size for either audience. Content creators frame critical content or graphics to fit within the 1.33 raster space. Audiences generally do not see such centrally framed information as distracting. However, audiences of 16:9 ratio scenes can find odd moving elements that are centrally framed. 4:3 content upconverted to a 16:9 standard is generally referred to as pillar boxed and many high definition television networks have adopted decoratively branded logos to fill the null area.
After the original 16:9 Action Plan of the early 1990s, the European Union has instituted the 16:9 Action Plan, just to accelerate the development of the advanced television services in 16:9 aspect ratio, both in PAL and also in HDTV. The Community fund for the 16:9 Action Plan amounted to €228 million.
In Europe, 16:9 is being adopted as the standard broadcast format for digital and high definition TV. Some countries have even adopted the format for analog television by means of the PALplus standard.
|Austria||ORF1, ORF2, ORF Sport Plus, ORF1 HD, ATV, PULS 4|
|Belgium||Flanders: all Flemish channels except TMF Flanders
Wallonia: La Une, La Deux, RTL TVI, Club RTL, Plug TV
|Bulgaria||The Voice TV, RE:TV, TV7*, RING.BG*, PRO.BG*
* Do not set the aspect ratio correctly when broadcasting in 16:9 and the image appears stretched on 4:3 TV sets. Such stations use mostly 4:3 programming.
|Czech Republic||TV Nova, Česká televize, TV Nova HD, TV Prima, TV Barrandov|
|Denmark||Almost all main channels|
|Finland||All main channels, including but not limited to YLE TV1, YLE TV2, MTV3, Nelonen|
|France||All nationwide channels on the French DVB-T (TNT) except NT1, BFM TV, I-Télé, Virgin 17, Gulli
Many more via ADSL, DVB-C and DVB-S;
Canal+ Décalé, Canal+ Family, Poker Channel, CinePlay, Ciné Cinéma Premier, OL TV, Motors TV, Disney Cinemagic, Disney Cinemagic + 1, NRJ Hits, Ciné Cinéma Premier HD, National Geographic HD, Ushuaia TV HD, Disney Cinemagic HD, MTV HD, NRJ 12 HD, iConcert HD, HD1, Melody Zen HD, Sci Fi Channel HD, 13ème Rue HD, Orange cinemax HD
|Germany||ARD (Das Erste, EinsExtra, EinsFestival, EinsPlus; BR and BR-alpha, HR, WDR, SWR, RBB, RB), ZDF, 3sat, Arte, DW, Phoenix; kabel eins, ProSieben, Sat.1; RTL, RTL II, Super RTL, VOX; and others (all main channels)|
|Greece||Skai TV, MTV Greece, ERT Digital|
|Hungary||Magyar Televízió (m1, m2), Life Network*, Ozone Network*
* Do not set the aspect ratio correctly when broadcasting in 16:9 and the image appears stretched on 4:3 TV sets. Such stations use mostly 4:3 programming.
|Ireland||RTÉ One, RTÉ Two, TV3, TG4, 3e, and Setanta Ireland|
|Italy||All the 10 SKY Cinema channels, all the 6 SKY Sport channels, all the 15 SKY Calcio channels, all the 60 SKY Prima Fila channels, Cult, MGM, Discovery Channel Italy, National Geographic Channel Italy, all dahlia TV channels, all Premium Calcio channels, Premium Cinema, Studio Universal, Rai Sport Più.|
|Luxembourg||RTL Télé Lëtzebuerg, Luxe.tv|
|Netherlands||Almost all nationwide channels (Netherlands Public Broadcasting, RTL, SBS), BravaHDTV|
|Norway||Almost all main channels|
|Poland||Polsat 2 International, Polsat News, Polsat Sport, Polsat Sport Extra, Canal+, Canal+ Film, Canal+ Sport, Ale Kino!, TVN (on DVB-T and in HD) TVN Siedem, Religia TV, TVN 24, TVN Meteo, TVN CNBC Biznes, TVN Style, TVN Turbo, TVP Kultura, TVP Historia, TVP1, TVP2, TVP Polonia, TVP HD, TVP Sport|
|Portugal||RTP1, RTP2 (both letterbox PALplus), TVCine 1, TVCine 2, TVCine 3, TVCine and in 2010, SIC.|
|Serbia||Cinemania, RTS Digital|
|Slovakia||Markíza, Slovenská televízia|
|Slovenia||RTS Maribor, RTS Maribor HD, Radiotelevizija Slovenija HD, INFO TV HD (occasionally 16:9: Radiotelevizija Slovenija 1, 2 and 3, POP TV, Kanal A, TV Pika) (16:9 Letterbox INFO TV, Sport Klub, TV3,)|
|Spain||Nationally: All HD channels, all Digital + Taquilla PPV channels, GOL TELEVISIÓN SD simulcast, Aragón Sat, Canal + Liga, Canal + Acción, Canal + DCine, Canal + Acción 30, Canal + Comedia, Canal + Comedia 30, Canal + Fútbol, Canal + 2, Golf +, Canal +, Canal + ...30, Canal + Eventos, Dcine Español, Canal + Deportes, Sportmanía, Mezzo, infoMeteoº, Viajar, Caza y Pesca, ETB SAT, AXN, TV3CAT and Teledeporte (on all channels all the time), antena.neox, antena.nova, La Sexta, Telecinco, La Siete, Galicia TV, antena 3, FactoríaDeFicción, Cuatroº, Extremadura TV and Canal 24 horas (on all channels most or some of their programs), Disney Channel, VEO, TV Canaria sat and Intereconomía (some programs are aired in anamorphic 4:3 aspect ratio but without been signalized or flagged as widescreen). Regionally and Locally: All HD channels, esMADRIDtv, Aragón Televisión, Més tv, MARESMEDIGITAL TV, ETB 3, ETB 1, ETB 2, TV3, 33, Súper3/300 and 3/24 (on all channels all the time), IB3, giralda tv, Telemadrid, TVG, G2, Canal 9, Canal Sur 2, Canal Sur, CyL7, 9laLoma, Punt 2, Canal Extremadura, laOtra, TV Almansa, Infocanal, 8madrid, BTV, MDC TELEVISIÓN and CMT 2 (on all channels most or some of their programs), Ver-T, Onda 6, lasprovincias tv, Popular TV, Kiss TV, CyL8, TV Canaria, TV Canaria dos, LDTV, 25tv and telebilbao and other channels owned by Local Media TV and INTERECONOMÍA BUSINESS (on all these channels a few programs are aired in anamorphic 4:3 aspect ratio but without been signalized or flagged as widescreen).
Since Cuatro began with 16:9 on DTT on some programs, on analog simulcast those programs are matted in a 16:9 letterbox and signalized in a way that widescreen TV sets automatically do a zoom in and cropping so only what is in the letterbox is viewable. Right now is the only channel to do so, the rest just do a 16:9 or 14:9 letterboxing or just anamorphic.
|Sweden||Almost all main channels|
|Switzerland||All SRG SSR idée suisse channels|
|UK||All main digital channels (BBC One, BBC Two, ITV, Channel 4 and Five), and a majority of minor channels. Older programmes filmed in 4:3 are usually transmitted in their original format, as cropping a 4:3 picture for 16:9 TVs has proved unpopular. However, confusingly some 4:3 programmes are still broadcast in a 16:9 format with widescreen signals, such as the BBC's recent broadcast of the strictly 4:3 show The Wire.|
|Israel||All main channels, including but not limited to Hot, Yes.|
|Australia||All main channels, known as Freeview.|
|Thailand||Channel 3 (only one 16:9 terrestrial TV) and satellite channels|
Often, screen specifications are given by their diagonal length. Here are some formulae that can help in the finding of height, width and area, where r stands for ratio and d for diagonal length.
Comparing two different aspect ratios is arguably difficult. Given the same diagonal, the 4:3 screen offers more area. For CRT-based technology, an aspect ratio that is closer to square is cheaper to manufacture. The same is true for projectors, and other optical devices such as cameras, camcorders, etc. For LCD and Plasma displays, however, the cost is more related to the area, so producing wider and shorter screens with the same advertised diagonal is more profitable.
|1.33:1||35 mm original silent film ratio, commonly known in TV and video as 4:3. Also standard ratio for MPEG-2 video compression. This format is still used in most personal video cameras today. It is the standard 16 mm and Super 35mm ratio.|
|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. Rarely used in theatrical context nowadays, but occasionally used for other context.|
|1.43:1||IMAX format. Imax productions use 70 mm wide film (the same as used for 70 mm feature films), but the film runs through the camera and projector sideways. This allows for a physically larger area for each image.|
|1.50:1||The aspect ratio of 35 mm film used for still photography when 8 perforations are exposed. Usually called 3:2. Also the native aspect ratio of VistaVision.|
|1.56:1||Widescreen aspect ratio 14:9. Often used in shooting commercials etc. as a compromise format between 4:3 (12:9) and 16:9, especially when the output will be used in both standard TV and widescreen. When converted to a 16:9 frame, there is slight pillarboxing, while conversion to 4:3 creates slight letterboxing.|
|1.66:1||35 mm Originally a flat ratio invented by Paramount Pictures, now a standard among several European countries; native Super 16 mm frame ratio. (5:3, sometimes expressed more accurately as "1.67".)|
|1.75:1||Early 35 mm widescreen ratio, primarily used by MGM and Warner Bros. between 1953 and 1955, and since abandoned.|
|1.78:1||Video widescreen standard (16:9), used in high-definition television, one of three ratios specified for MPEG-2 video compression. Also used in some personal video cameras.|
|1.85:1||35 mm US and UK widescreen standard for theatrical film. Introduced by Universal Pictures in May, 1953. Projects approximately 3 perforations ("perfs") of image space per 4 perf frame; films can be shot in 3-perf to save cost of film stock.|
|2.00:1||Original SuperScope ratio, also used in Univisium. Used as a flat ratio for some American studios in the 1950s, abandoned in the 1960s, but recently popularized by the Red One camera system.|
|2.20:1||70 mm standard. Originally developed for Todd-AO in the 1950s. 2.21:1 is 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, but often referred to as 2.35 anyway, due to old convention. (Note that anamorphic refers to the compression of the image on film to maximize an area slightly taller than standard 4-perf Academy aperture, but presents the widest of aspect ratios.)|
|2.39:1||35 mm anamorphic from 1970 onwards. Sometimes rounded up to 2.40:1 Often commercially branded as Panavision format or 'Scope.|
|2.55:1||Original aspect ratio of CinemaScope before optical sound was added to the film in 1954. 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).|
|2.66:1||Full frame output from Super 16 mm negative when an anamorphic lens system has been used. Effectively, an image that is of the ratio 2.66:1 is squashed onto the native 15:9 aspect ratio of a Super 16 mm negative.|
|2.76:1||MGM Camera 65 (65 mm with 1.25x anamorphic squeeze). Used only on a handful of films between 1956 and 1964, such as Ben-Hur (1959).|
|4.00:1||Rare use of Polyvision, three 35 mm 1.33 images projected side by side. First used on Abel Gance's Napoléon (1927).|
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 2.39:1 aspect ratio. It was filmed in Super 35 and, in addition to being presented in cinemas and television in the Original Aspect Ratio of 2.39:1, it was also broadcast without the matte altering the aspect ratio to the television standard of 1.33:1. Because of the varied ways in which films are shot, IAR (Intended Aspect Ratio) is a more appropriate term, but is rarely used.
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.
Multiple aspect ratios create additional burdens on filmmakers and consumers, and confusion among TV broadcasters. It is common for a widescreen film to be presented in an altered format (cropped, letterboxed or expanded beyond the Original Aspect Ratio). It is also not uncommon for windowboxing to occur (when letterbox and pillarbox happen simultaneously). For instance, a 16:9 broadcast could embed a 4:3 commercial within the 16:9 image area. A viewer watching on a standard 4:3 (non-widescreen) television would see a 4:3 image of the commercial with 2 sets of black stripes, vertical and horizontal (windowboxing or the postage stamp effect). A similar scenario may also occur for a widescreen set owner when viewing 16:9 material embedded in a 4:3 frame, and then watching that in 16:9. Active Format Description is a mechanism used in digital broadcasting to avoid this problem. It is also common that a 4:3 image is stretched horizontally to fit a 16:9 screen to avoid pillar boxing.
Both PAL and NTSC have provision for some data pulses contained within the video signal used to signal the aspect ratio (See ITU-R BT.1119-1 - Widescreen signaling for broadcasting). These pulses are detected by television sets that have widescreen displays and cause the television to automatically switch to 16:9 display mode. When 4:3 material is included (such as the aforementioned commercial), the television switches to a 4:3 display mode to correctly display the material. Where a video signal is transmitted via a European SCART connection, one of the status lines is used to signal 16:9 material as well.
Common aspect ratios in still photography include 4:3 (1.33) used by most digital point-and-shoot cameras, Four Thirds system cameras and medium format 645 cameras; 3:2 (1.5) used by 35mm film, APS-C ("classic" mode) and most DSLRs; 1.81:1 (close to 16:9) used by APS-H high definition mode and some Panasonic multi‐aspect Four Thirds and compact cameras; 3:1 used by APS‐P panoramic mode; and 1:1 (square) in a variety of cameras.
Common print sizes in the U.S. (in inches) include 4×6 (1.5), 5×7 (1.4), 4×5 and 8×10 (1.25), and 11×14 (1.27); large format cameras typically use one of these aspect ratios. Medium-format cameras typically have format designated by nominal sizes in centimeters (6×6, 6×7, 6×9, 6×4.5), but these numbers should not be interpreted as exact in computing aspect ratios.
For analog projection of photographic slides, projector and screen use a 1:1 aspect ratio, supporting landscape and portrait orientation equally well. In contrast, digital projection technology typically supports portrait oriented images only at a fraction of the resolution of landscape oriented images. For example, projecting a digital still image having a 3:2 aspect ratio on a 16:9 projector, employs 84.3% of available resolution in landscape orientation, but only 37.5% in portrait orientation.
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