Aspect ratio (image)

Five common aspect ratios
4:3
3:2
16:9
1.85:1
2.39:1

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"), with the latter particularly used for pixel dimensions, such as 640×480. Cinematographic aspect ratios are usually denoted as a (rounded) decimal multiple of width vs unit height, whilst photographic and videographic aspect ratios are usually defined and denoted by whole number ratios of width to height. In digital images there is a subtle distinction between the Display Aspect Ratio (the image as displayed) and the Storage Aspect Ratio (the ratio of pixel dimensions); see distinctions, below.

The most common aspect ratios used today in the presentation of films in movie theaters are 1.85:1 and 2.39:1.[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 for high-definition television and European digital television. Other cinema and video aspect ratios exist, but are used infrequently. As of 2010, nominally 21:9 (2.33) aspect TVs have been introduced by Philips and Vizio (the latter using an LCD from AU Optronics) as "cinema" displays, though the resolution is more precisely 2560×1080 = 2.37, and the aspect ratio is not standardized in HDTV.

In still camera photography, the most common aspect ratios are 4:3, 3:2, and more recently being found in consumer cameras 16:9[2]. Other aspect ratios, such as 5:4, 6:7, and 1:1 (square format), are used in photography as well, particularly in medium format and large format.

With television, DVD and Blu-ray, converting formats of unequal ratios is achieved by either: enlarging the original image (by the same factor in both directions) 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 (hence distorting) the image to fill the receiving format's ratio, by scaling by different factors in both directions, possibly scaling by a different factor in the center and at the edges (as in Wide Zoom mode).

Contents

Practical Limitations

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.[3]

With a space designated for the standard optical soundtrack, and the frame size reduced to maintain an image that is wider than tall (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.

Cinema terminology

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 in 1.66:1). 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 (up to 2.66:1), Todd-AO (2.20:1), and VistaVision (initially 1.50:1, now 1.66:1 to 2.00:1) 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.

Movie camera systems

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 is 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.

Current video standards

4:3 standard

The 4:3 ratio (generally named as "Four-Three", "Four-by-Three", or "Four-to-Three") for standard television has been in use since television's origins and many computer monitors employ the same aspect ratio. 4:3 is the aspect ratio used for 35 mm films in the silent era and used today for film production under the name Super 35. It is also very close to the 1.37:1 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 standard

16:9 (generally named as "Sixteen-Nine", "Sixteen-by-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, and 16:9 is the only widescreen aspect ratio natively supported by the DVD. DVD producers can also choose to show even wider ratios such as 1.85:1 and 2.39:1[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.

Why 16:9 was chosen by the SMPTE

Equal area comparison of the aspect ratios used by Dr. Powers to derive the SMPTE 16:9 standard.[4] TV 4:3/1.33 in red, 1.66 in orange, 16:9/1.78 in blue, 1.85 in yellow, Panavision/2.2 in mauve and CinemaScope/2.35 in purple.

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, shaped 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 1.77:1 and all of them also covered a smaller common inner rectangle with the same aspect ratio 1.77:1.[4] The value found by Powers is exactly the geometric mean of the extreme aspect ratios, 4:3 (1.33:1) and 2.35:1, which is coincidentally close to 16:9 (1.78:1). Note that applying the same geometric mean technique to 16:9 and 4:3 approximately yields the 14:9 aspect ratio, which is likewise used as a compromise between these ratios.[5]

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[6] 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 see such centrally framed information as distracting. However, audiences of 16:9 ratio scenes can find odd moving elements that are centrally framed. This has similarities to the effect a filming technique called Open matte can have. 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.

16:9 in Europe

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.

Country Channel
Albania Albania DigiGold
Austria Austria ORF1, ORF2, ORF Sport Plus, ORF1 HD, ATV, Puls 4, Servus TV
Belgium Belgium All channels, except TMF
Bulgaria 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 Czech Republic TV Nova, Česká televize, TV Nova HD, TV Prima, TV Barrandov
Denmark Denmark Almost all main channels as 16:9 is the national standard for television.
Finland Finland Almost all main channels as 16:9 is the national standard for television, including but not limited to YLE TV1, YLE TV2, MTV3, Nelonen
France France All nationwide channels on the French DVB-T (TNT) except NT1
And almost all pay channel via TNT, 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 and SD, National Geographic HD and SD, Ushuaia TV HD and SD, Disney Cinemagic HD and SD, MTV HD, NRJ 12 HD and SD, iConcert HD, HD1, Melody Zen HD, Sci Fi Channel HD and SD, 13ème Rue HD and SD, Orange cinemax HD...
Germany Germany ARD (Das Erste, EinsExtra, EinsFestival, EinsPlus; BR and BR-alpha, HR, WDR, SWR, RBB, RB), ZDF, 3sat, Arte, DW-TV, Phoenix; kabel eins, ProSieben, Sat.1; RTL, RTL II, Super RTL, VOX; and others (all main channels)
Greece Greece Skai TV[7], MTV Greece, ERT Digital
Hungary Hungary Magyar Televízió (m1, m2), Duna TV (both standard and HD)[8], Duna2, LifeNetwork*, OzoneNetwork, Viasat3, TV6, ATV, Spektrum TV, DigiSport
* 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.
Republic of Ireland Ireland RTÉ One, RTÉ Two, TV3, TG4, 3e, and Setanta Ireland
Italy Italy All the 10 SKY Cinema channels, all the 6 SKY Sport channels, all the 15 SKY Calcio channels, all the 30 SKY Prima Fila channels, Cult, MGM, Discovery Channel Italy, National Geographic Channel Italy, AXN Italy, E! (localized version), all the 6 dahlia TV channels, all the 6 Premium Calcio, all the 3 Premium Cinema channels, Studio Universal, Rai Sport 1, Rai Sport 2, QVC Italy.

Occasional 16:9 widescreen programming may be shown also on RAI, Mediaset and La7 networks and few local television networks. Some television networks do not set correctly the aspect ratio when broadcasting.
Luxembourg Luxembourg RTL Télé Lëtzebuerg, Luxe.tv
Montenegro Montenegro RTV Panorama
Netherlands Netherlands All nationwide channels (Netherlands Public Broadcasting, RTL, SBS), BravaHDTV. Only 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.
Norway Norway Almost all main channels as 16:9 is the national standard for television.
Poland Poland TVP1, TVP2, TVP Polonia, TVP HD, TVP Sport, TVP Kultura, TVP Historia, Polsat (in HD), Polsat 2, Polsat News, Polsat Sport, Polsat Sport Extra, Polsat Café, Polsat Film, Polsat Play, Canal+, Canal+ Film, Canal+ Sport, Ale Kino!, TVS, TVN (on DVB-T and in HD), TVN +1, TVN Siedem, Religia TV, TVN 24, TVN Meteo, TVN CNBC Biznes, TVN Style, TVN Turbo, TVN Warszawa, nSport, Mango 24, nFilm HD, nFilm HD 2, 4fun.tv, Eska TV, TV4, Orange Sport Info, Domo, Kuchnia.tv, MiniMini
Portugal Portugal RTP1 & RTP2 using letterbox PALplus, TVCine 1,2,3 & TVCine , Canal Q, Sony Entertainment Television, SportTV HD ; Golfe (SD & HD) & Liga Inglesa (HD-only channel).
Romania Romania Occasional 16:9 widescreen programming shown on The Romanian Public Broadcaster's channels (TVR 1, TVR 2, TVR Cultural), Sport.ro, B1 TV and DigiSport. SD version aired in 16:9-in-4:3 letterbox on PRO Cinema and MTV Romania. Full 16:9 widescreen programming aired on all HD channels: TVR HD, PRO TV HD and Sport.ro HD.
Serbia Serbia RTS Digital, RTS HD, Arena Sport 1, 2, 3 & 4 HD, Cinemania,
Slovakia Slovakia Markíza, Slovenská televízia, JOJ
Slovenia Slovenia Almost all main channels (Televizija Slovenija (TVS 1, TVS 2 and TVS 3), Info TV, POP TV, Kanal A, TV Pika, Sport TV 1, Sport TV 2, Sportklub+, Golfklub, HBO Slovenija, RTS Maribor*) and all HD channels (Televizija Slovenija HD, Info TV HD, RTS Maribor HD)
* Do not set the aspect ratio correctly when broadcasting in 16:9 and the image appears stretched on 4:3 TV sets.
Spain Spain Almost all main channels as 16:9 is the national standard for television.
Sweden Sweden Almost all main channels as 16:9 is the national standard for television.
Switzerland Switzerland All SRG SSR idée suisse channels
Turkey Turkey TRT Türk
Ukraine Ukraine English Club TV
United Kingdom UK All main digital channels and their sister 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.

16:9 in Asia

Country Channel
Qatar Qatar All Al Jazeera Sports channels, Excluding JSC Sport +8 and ESPN channels.
Israel Israel All main channels, including but not limited to Hot, Yes.
Japan Japan Japan pioneered in its analogue HDTV system (MUSE) in 16:9 format, started in 1980s. Currently all main channels have Digital terrestrial television channels in 16:9 while being simulcast in analogue 4:3 format. Many satellite broadcast channels are being broadcasted in 16:9 as well.
Thailand Thailand Channel 3 (only one 16:9 terrestrial TV) and satellite channels
Vietnam Vietnam Vietnam Multimedia Corporation (VTC): HD channels were made by VTC and bought out the rights (some channels were made by upscaling from SDTV)

Ho Chi Minh City Cable Television (HTVC): HD channels were bought out the rights (some channels were made by upscaling from SDTV)

Saigon Tourist Cable Television (SCTV): HD channels were bought out the rights (some channels were made by upscaling from SDTV)

KPlus (K+): Coming soon

16:9 in Oceania

Country Channel
Australia Australia All major stations since the introduction of DVB-T in 2001, now known as Freeview.
New Zealand New Zealand All major channels.

Obtaining height, width and area of the screen

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.

h=\frac{d}{\sqrt{r^2+1}} \qquad l=\frac{d}{\sqrt{\frac{1}{r^2}+1}} \qquad A=\frac{d^2}{r+\frac{1}{r}}

Distinctions

This article primarily addresses the aspect ratio of images as displayed, which is more formally referred to as the Display Aspect Ratio (DAR). In digital images, there is a distinction with the Storage Aspect Ratio (SAR), which is the ratio of pixel dimensions. If an image is displayed with square pixels, then these ratios agree; if not, then non-square, "rectangular" pixels are used, and these ratios disagree. The aspect ratio of the pixels themselves is known as the Pixel Aspect Ratio (PAR) – for square pixels this is 1:1 – and these are related by the identity:

SAR × PAR = DAR.

Rearranging (solving for PAR) yields:

PAR = DAR/SAR.

For example, a 640 × 480 VGA image has a SAR of 640/480 = 4:3, and if displayed on a 4:3 display (DAR = 4:3) has square pixels, hence a PAR of 1:1. By contrast, a 720 × 576 D-1 PAL image has a SAR of 720/576 = 5:4, but is displayed on a 4:3 display (DAR = 4:3), so by this formula it would have a PAR of (4:3)/(5:4) = 16:15.

However, because standard definition digital video was originally based on digitally sampling analog television, the 720 horizontal pixels actually capture a slightly wider image to avoid loss of the original analog picture. (In actual images these extra pixels are often partly or entirely black.) Hence the actual pixel aspect ratio for PAL video is a little different from that given by the formula, specifically 59:54 (approximately 1.09:1) for PAL and 10:11 (approximately 0.91:1) for NTSC. For consistency, the same effective pixel aspect ratios are used even for standard definition digital video originated in digital form rather than converted from analog. For more details refer to the main article.

In analog images such as film there is no notion of pixel, nor notion of SAR or PAR, and "aspect ratio" refers unambiguously to DAR. Actual displays do not generally have non-square pixels, though digital sensors might; they are rather a mathematical abstraction used in resampling images to convert between resolutions.

Non-square pixels arise often in early digital TV standards, related to digitalization of analog TV signals – whose horizontal and vertical resolutions differ and are thus best described by non-square pixels – and also in some digital videocameras and computer display modes, such as Color Graphics Adapter (CGA). Today they arise particularly in transcoding between resolutions with different SARs.

DAR is also known as Image Aspect Ratio and Picture Aspect Ratio, though the latter can be confused with Pixel Aspect Ratio.

Visual comparisons

Comparing two different aspect ratios poses some subtleties – when comparing two aspect ratios, one may compare images with equal height, equal width, equal diagonal, or equal area. More amorphous questions include whether particular subject matter has a natural aspect ratio (panoramas being wide, full-length images of people being tall), or whether a particular ratio is more or less aesthetically pleasing – the golden ratio (1.618) is seen as especially pleasing, though only the 16:10 format is close to it.

Given the same diagonal, the 4:3 screen offers more area, because it is closer to square (which maximizes area given a diagonal). 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 yields the same advertised diagonal but lower area, and hence is more profitable.

The following compares crops of a given image at 4:3 and 16:9, with different parameters equal; note that in terms of subject, the squarer aspect ratio emphasizes the public square, while the wider aspect ratio emphasizes the wide building.

4:3 (1.33:1)
16:9 (1.78:1)
4:3 (1.33:1)
16:9 (1.78:1)
4:3 (1.33:1)
16:9 (1.78:1)
4:3 (1.33:1)
16:9 (1.78:1)

Previous and presently used aspect ratios

See list of common resolutions for a listing of computer resolutions and aspect ratios.
See list of film formats for a full listing of film formats, including their aspect ratios.
Comparison between several film aspect ratios with the heights forced to be equal.
1.33 (4
3): 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 many personal video cameras today. It is the standard 16 mm and Super 35mm ratio.
1.37
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
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 (3
2): The aspect ratio of 35 mm film used for still photography when 8 perforations are exposed. Also the native aspect ratio of VistaVision.
1.56 (14
9): Widescreen aspect ratio sometimes used in shooting commercials etc. as a compromise format between 4:3 (12:9) and 16:9. When converted to a 16:9 frame, there is slight pillarboxing, while conversion to 4:3 creates slight letterboxing.
1.66 (15
9 = 5:3): 35 mm Originally a flat ratio invented by Paramount Pictures, now a standard among several European countries; native Super 16 mm frame ratio. (Sometimes expressed more accurately as "1.67".)
1.75
Early 35 mm widescreen ratio, primarily used by MGM and Warner Bros. between 1953 and 1955, and since abandoned.
1.78 (16
9): Video widescreen standard, used in high-definition television, one of three ratios specified for MPEG-2 video compression. Also used increasingly in personal video cameras.
1.85
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
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
70 mm standard. Originally developed for Todd-AO in the 1950s.
2.21
Specified in MPEG-2 for 2.20:1 movies, but hardly used.
2.33 (21
9 = 7:3),
2.37
As of 2010, nominally 21:9 aspect TVs have been introduced as "cinema" displays, though the resolution is 2560×1080 and the ratio more precisely 2.37:1, i.e. 64:27 not 63:27. The aspect ratio is not recognized by storage and transmission standards.
2.35
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,[1] 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,
2.40
35 mm anamorphic from 1970 onwards. 2.39:1 is sometimes rounded up to 2.40:1[1]. Often commercially branded as Panavision format or 'Scope.
2.55
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
Cinerama at full height (three specially captured 35 mm images projected side-by-side into one composite widescreen image).
2.66
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
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
Rare use of Polyvision, three 35 mm 1.33 images projected side by side. First used in 1927 on Abel Gance's Napoléon.

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 2.39:1 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 (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.

Problems in film and television

A windowboxed image

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.

Still photography

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. Many digital cameras offer user options for selecting image aspect ratio, but all this function does is reject the storage of rectangular edge pixel blocks from the native sensor resolution.

The reason for DSLR image sensors being the flatter 3:2 versus the taller point-and-shoot 4:3 is that DSLRs were designed to match the legacy 35mm SLR film, whereas the majority of digital cameras were designed to match the predominant computer displays of the time, with VGA, SVGA, XGA and UXGA all being 4:3. (Widescreen computer monitors did not become popular until the advent of HDTV, and when processor speeds got fast enough to smoothly handle higher definition video.)

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 horizontal and vertical orientation equally well. In contrast, digital projection technology typically supports vertically 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 horizontal orientation, but only 37.5% in vertical orientation.

See also

References

Cited references
  1. ↑ 1.0 1.1 1.2 1.3 The 2.39:1 ratio is commonly labeled 2.40:1, e.g., in the American Society of Cinematographers' American Cinematographer Manual, and is mistakenly referred to as 2.35:1 (only cinema films before the 1970 SMPTE revision used 2.35:1).
  2. ↑ Panasonic Introduces 2 New Cameras. India: Tech Tree. http://www.techtree.com/India/News/Panasonic_Introduces_2_New_Cameras/551-97953-893.html 
  3. ↑ Burum, Steped (2004). American Cinematographer Manual (9th ed.). ASC Press. ISBN 0-935578-24-2 
  4. ↑ 4.0 4.1 TECHNICAL BULLETIN: Understanding Aspect Ratios. The CinemaSource Press. 2001. http://www.cinemasource.com/articles/aspect_ratios.pdf#page=8. Retrieved 2009-10-24. 
  5. ↑ US 5956091, "Method of showing 16:9 pictures on 4:3 displays", issued September 21, 1999 
  6. ↑ I. Baker, BBC (1999-08-25). Safe areas for widescreen transmission. http://www.ebu.ch/en/technical/trev/trev_280-baker.pdf. Retrieved 2009-10-27. 
  7. ↑ "ΣΚΑΪ | Αρχική σελίδα (English: SKAI: Initial Page)". Skai.gr. http://www.skai.gr. Retrieved 2008-11-07. 
  8. ↑ http://www.dunatv.hu/footer/vetelilehetosegek
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