IMAX

IMAX theatre at the Melbourne Museum complex, Australia

BFI London IMAX by night

IMAX (short for Image Maximum) is a film format created by Canada's IMAX Corporation that has the capacity to display images of far greater size and resolution than conventional film display systems available at the time. A standard IMAX screen is 22 m wide and 16.1 m high (72.6 ft x 52.8 ft), but can be larger. As of 2008, IMAX is the most widely used system for large-format, special-venue film presentations. As of March 2007, there were 280 IMAX theatres in 38 countries (60% of these are located in Canada and the United States). Half of these are commercial theatres and half are in educational venues. A variation of IMAX, IMAX DOME (originally called OMNIMAX), is designed for projection on tilted dome screens. Films can also be projected in 3D with IMAX 3D. The Hyderabad, India IMAX has the world's largest display screen. The biggest "IMAX Dome" is in the Liberty Science Center in Jersey City, New Jersey. The world's largest IMAX 3D cinema screen is located in Melbourne, Australia.

The desire to increase the visual impact of film has a long history. In 1929, Fox introduced Fox Grandeur, the first 70 mm movie format, which quickly fell from use. In the 1950s, CinemaScope and VistaVision widened the projected image from 35 mm film, and there were multi-projector systems such as Cinerama for even wider presentations. While impressive, Cinerama was difficult to set up, and the seams between adjacent projected images were difficult to hide.

History

The IMAX system was developed by four Canadians: Graeme Ferguson, Roman Kroitor, Robert Kerr and William C. Shaw.

During Expo 67 in Montreal, Canada, In the Labyrinth, their multi-projector giant-screen system had a number of technical difficulties that led them to design a single-projector/single-camera system. Tiger Child, the first IMAX film, was demonstrated at Expo '70 in Osaka, Japan. The first permanent IMAX system was set up in Toronto at Ontario Place in 1971, and is still in operation. During Expo '74 in Spokane, Washington, a very large IMAX screen that measured 90 x 65 ft (27.3 x 19.7 m) was featured in the US Pavilion (the largest structure in the expo). About 5 million visitors viewed the screen, which covered a person's total field of vision when looking directly forward. This easily created a sensation of motion for nearly everyone, and motion sickness in a few viewers. However, it was only a temporary screen for the six-month duration of the Expo. Several years later, a standard size IMAX screen was installed, and is still in operation at the renamed "Riverfront Park IMAX Theatre."

The first permanent IMAX Dome installation, the Reuben H. Fleet Space Theater and Science Center, opened in San Diego's Balboa Park in 1973. The first permanent IMAX 3D theatre was built in Vancouver, British Columbia for Transitions at Expo '86, and is still in use. It is located at the tip of Canada Place, a Vancouver landmark.

Over the summer of 2006, IMAX's stock fell markedly (by as much as 60%) with the announcement of an SEC investigation, falling again when the announced third quarter earnings were behind the previous year's.

Technical aspects

A comparison between 35 mm and 15/70 mm negative areas

An IMAX camera inside a display case

The 15 kW Xenon short-arc lamp used in IMAX projectors

The intent of IMAX is to dramatically increase the resolution of the image by using much larger film stock at a resolution comparable to about 10000 x 7000 pixels (70 megapixels). To do this, 70 mm film stock is run "sideways" through the cameras. While traditional 70 mm film has an image area that is 48.5 mm wide and 22.1 mm tall (for Todd-AO), in IMAX the image is 69.6 mm wide and 48.5 mm tall. In order to expose at standard film speed of 24 frames per second, three times as much film needs to move through the camera each second.

Drawing the large-format film through the projector was a difficult technical problem to solve; conventional 70 mm systems were not steady enough for the 586x magnification. IMAX projection involved a number of innovations. William Shaw of IMAX adapted an Australian patent for film transport called the "rolling loop" by adding a compressed air "puffer" to accelerate the film, and put a cylindrical lens in the projector's "block" for the film to be vacuumed up against during projection (called the "field flattener" because it served to flatten the image field). Because the film actually touches the "field flattener" lens, the lens itself is twice the height of the film and is connected to a pneumatic piston so it can be moved up or down while the projector is running. This way, if a piece of dust comes off the film and sticks to the lens, the projectionist can switch to the clean side of the lens at the push of a button. The lens also has "wiper bars" made of a felt or brush-like material which can wipe the dust off the lens as it moves up or down to keep the show clean. IMAX projectors are pin stabilized, meaning 4 registration pins engage the sprockets at the corners of the projected frame to ensure perfect alignment. Shaw added cam-controlled arms to decelerate each frame to eliminate the microscopic shaking as the frame "settled" onto the registration pins. The projector's shutter is also open for around 20% longer than in conventional equipment and the light source is brighter. The largest 12-18 kW xenon arc lamps have hollow, water-cooled electrodes. An IMAX projector is therefore a substantial piece of equipment, weighing up to 1.8 tonnes and towering at over 70" [178 cm] tall and 75" [195 cm] long. The xenon lamps are made of a thin layer of quartz crystal, and contain xenon gas at a pressure of about 25 atmospheres; because of this, projectionists are required to wear protective body armor when changing or handling these lamps because the flying shards of crystal (should the lamp fall and crash) could be deadly when combined with the high pressure of the gas within.

IMAX uses a stronger "ESTAR" (Kodak's trade name for PET film) base. The reason is not for strength, but precision. Developing chemicals do not change the size or shape of Estar, and IMAX's pin registration (especially the cam mechanism) is intolerant of either sprocket-hole or film-thickness variations. The IMAX format is generically called "15/70" film, the name referring to the 15 sprockets per frame of 70 mm stock. The bulk of the film requires large platters rather than conventional film reels.

In order to use more of the image area, IMAX film does not include an embedded soundtrack. Instead the IMAX system specifies a separate six-channel 35 mm magnetic tape synchronized to the film. (This original system--35 mm mag tape locked to a projector--was commonly used to "dub" or insert studio sound into the mixed soundtrack of conventional films.) By the early '90s, a separate digital 6-track source was synchronized using a more precise pulse generator as a source for a conventional SMPTE timecode synchronization system. This development presaged conventional theatrical multichannel sound systems such as Dolby Digital and Digital Theater System. This digital source came in the form of a unit called a DDP (Digital Disc Playback) in which the soundtrack was recorded onto multiple CD-ROM discs which would play the sound which was recorded to the discs as a digital audio file. This DDP system has been replaced in almost all theaters with the newer DTAC (Digital Theater Audio Control) system which utilizes a computer running the IMAX's proprietary DTAC software. The software works in a similar style as the DDP except that instead of the audio file being based on discs, it is instead played directly off a hard drive in the form of a single uncompressed audio file containing the 6 channels which are distributed directly to the amplifiers rather than using a decoding method such as Dolby Digital. Many IMAX theaters place speakers directly behind the screen as well as distributing the speakers around the theater to create a three-dimensional effect.

IMAX theater construction also differs significantly from conventional theaters. The increased resolution allows the audience to be much closer to the screen; typically all rows are within one screen height. (Conventional theaters seating runs 8 to 12 screen heights) Also, the rows of seats are set at a steep angle (Up to 23 degrees in some domed theaters) so that the audience is facing the screen directly.

IMAX Dome/OMNIMAX

The frame layout of the IMAX Dome film.

The Control room of an IMAX Dome Theatre.

In the late 1960s the San Diego Hall of Science (now known as the Reuben H. Fleet Science Center) began searching North America for a large-format film system to project on the dome of their planned 76-foot tilted dome planetarium. One of the front-running formats was a double-frame 35 mm system, until they saw IMAX. The IMAX projector was unsuitable for use inside a dome because it had a 12-foot-tall lamp house on top. However, IMAX Corporation was quick to cooperate and was willing to redesign its system. IMAX designed an elevator to lift the projector to the center of the dome from the projection booth below. Spectra Physics designed a suitable lamphouse that took smaller lamps (about 18 inches long) and placed the bulb behind the lens instead of above the projector. Leitz of Canada developed a fisheye lens that would project the image onto a dome instead of a flat screen.

The dome system, which the San Diego Hall of Science called OMNIMAX, uses a fisheye lens on the camera that squeezes a highly distorted 180 degree field of view onto the 70 mm IMAX film. The lens is aligned below the center of the frame and most of the bottom half of the circular field falls beyond the edge of the film. The part of the field that would fall below the edge of the dome is masked off. When filming, the camera is aimed upward at an angle that matches the tilt of the dome. When projected through a matching fisheye lens onto a dome, the original panoramic view is recreated. OMNIMAX wraps 180 degrees horizontally, 100 degrees above the horizon and 22 degrees below the horizon for a viewer at the center of the dome. OMNIMAX premiered in 1973 at the Reuben H. Fleet Space Theater and Science Center showing two OMNIMAX features, Voyage to the Outer Planets (produced by Graphic Films) and Garden Isle (by Roger Tilton Films) on a double bill.

IMAX has since renamed the system IMAX Dome. Many theaters continue to call it OMNIMAX.

OMNIMAX theaters are now in place at a number of major American museums, particularly those with a scientific focus, where the technical aspects of the system may be highlighted as part of the theme interest. The projection room is often windowed to allow public viewing and accompanied by informational placards like any exhibit. Inside the theatre, the screen may be a permanent fixture, such as at the St. Louis Science Center (which also plays a short educational video about the OMNIMAX system just before the feature film); or lowered and raised as needed, such as at the Science Museum of Minnesota (where it shares an auditorium with a standard IMAX screen). Before the feature begins, the screen is backlit to show the speakers and girders behind the screen. IMAX Dome screens may also be found at several major theme parks.

The OMNIMAX experience is quite different from that of a regular IMAX theater. The image wraps around both sides of the viewer and upwards as well, which can give the impression one is actually inside the scene being projected. (A plain IMAX screen is large but does not create such a natural feeling of immersion because the viewer is aware that the scene ends where the rectangular walls and ceiling begin.)

But despite their impressive capabilities and unique experience, the system seems might remain a novelty rather than a widespread commercial phenomenon. Relative to their size, OMNIMAX theaters are very expensive to build and maintain, and have a relatively small seating capacity. To make matters worse, only those seats closest to the center of the theater provide the full effect of the immersive view. Museums are able to run the theaters at a profit only because they are able to subrogate the construction expenses through grants and public fundraising and then show relatively inexpensive documentary films, often while still being able to keep admission prices lower than those of standard cinemas. In this way, OMNIMAX theaters have become a "cash cow" for financially strapped public institutions.

It would take a tremendous amount of financial dedication to make OMNIMAX movies commercially viable, but the recipe is there. Many analysts predict it is only a matter of time before this phenomenal format becomes the norm. As more and more people choose to stay home rather than go to the theatres, many movie executives are being forced to think outside the box. Some say this format could be the thing that brings wonder back to the cinema, providing an experience that no home theatre could ever hope to match.

Another use of IMAX Dome technology is to provide an immersive visual experience to go with a ride simulator, as in The Simpsons Ride (replacing the older Back to the Future: The Ride). IMAX Dome was also used in the former EPCOT attraction Horizons and another Disney attraction, Soarin' Over California. "Soarin'" Featured at Disney's California Adventure and EPCOT.

IMAX 3D

IMAX 3D theatre in Eilat, Israel

To create the illusion of three-dimensional depth, the IMAX 3D process uses two camera lenses to represent the left and right eyes. The two lenses are separated by an interocular distance of 64mm/2.5", the average distance between a human's eyes. By recording on two separate rolls of film for the left and right eyes, and then projecting them simultaneously, we can be tricked into seeing a 3D image on a 2D screen. The IMAX 3D camera is cumbersome, weighing over 113kg/250lbs. This makes it difficult to film on-location documentaries.

There are two methods to creating the 3D illusion in the theatre. The first involves polarization. During projection, the left and right eye images are polarized perpendicular to one another as they are projected onto the IMAX screen. By wearing special eyeglasses with lenses polarized in their respective directions to match the projection, the left eye image can be viewed only by the left eye since the polarization of the left lens will cancel out that of the right eye projection, and the right eye image can be viewed only by the right eye since the polarization of the right lens will cancel out that of the left eye projection. Another method for 3D projection involves LCD shutter glasses. These glasses contain LCD panels which are synchronised to the projector which alternates rapidly at 96 frames per second between displaying the left and right images which are momentarily viewed by the appropriate eye by allowing that eye's panel to become transparent while the other remains opaque. While the panels within these active-shutter 3D glasses alternate at 96 frames per second, the actual film is displayed at 24 frames per second.

One particular problem that 3D movies face is that the 3D effect does not extend past the boundaries of the physical screen. It is for this reason that the screen must be large enough to cover as much of the viewer's peripheral vision as possible. Another problem with IMAX 3D movies is due to an inherent difference between our eyes and the film format. Because of the large negative, depth of field is dramatically reduced, causing an often distracting depiction of the scene. Computer-generated imagery films do not have this problem as they are able to control the depth of field in the images to allow everything to be in focus. While some may argue that this is less artistic than regular 2D films that purposefully employ shallow depth of field for aesthetic reasons, IMAX screens take up more of the viewer's vision than regular 2D films, and therefore the viewer can be disoriented by seeing images that are out of focus. The biggest 3D IMAX screen is located in Melbourne, Australia. The largest 3D IMAX screen in Asia is the San Miguel-Coca Cola IMAX Theatre and is located at the SM Mall of Asia.

Improvements in the sound systems have included a 3D sound system and the elliptical pattern speaker clusters.

IMAX HD

Further improvements and variations on IMAX include the possibility of a faster 48 frames per second rate, known as IMAX HD. This system was tested in 1992 at the Canada Pavilion of the Seville Expo '92 with the film Momentum. It was deemed too costly and abandoned but not before many theaters were retrofitted to project at 48 frames, especially in Canada.

A theme park in Germany also used IMAX HD for a film in the mid-1990s. Soarin' Over California, originally built at Disney's California Adventure before being replicated at Epcot, features a modification of both IMAX HD and IMAX Dome, projecting in 48 frames per second.

IMAX Digital 3D

A new IMAX projection system slated for use in mid-2008 simulates a 3D view and uses new digital technology. This will alleviate the need for the use of bulky film reels and facilitate inexpensive distribution of IMAX features. Deals have already been signed with Hollywood studios for such features, such as "Shrek Goes Forth 3D" .

IMAX is negotiating with Texas Instruments to use TI's Digital Light Processing technology as part of IMAX's proprietary system. Originally, the company had been considering using two Sony 4K projectors.

IMAX recently signed a deal with AMC to start utilizing this new technology beginning July 2008.

Content

Although IMAX is an impressive format from a technical perspective, its popularity as a motion picture format has traditionally been limited. The expense and logistics of producing and presenting IMAX films has dictated a shorter running time compared to conventional movies for most presentations (typically around 40 minutes). The majority of films in this format tend to be documentaries ideally suited for institutional venues such as museums and science centers. IMAX cameras have been taken into space aboard the Space Shuttle, to Mount Everest, to the bottom of the Atlantic ocean, and to the Antarctic to film such documentaries. Although IMAX documentaries have been praised for their technical quality, critics have also complained that many have banal narration.

Some IMAX theaters had shown conventional films (using conventional projection equipment) as a sideline to the native IMAX presentations. In the late 1990s there was a wave of interest in broadening the use of IMAX as an entertainment format. A few pure entertainment IMAX short films have been created, notably T-Rex: Back to the Cretaceous (directed by Brett Leonard), which had a successful run in 1998 and Haunted Castle, released in 2001 (both of these were IMAX 3D films). In 1999, The Old Man and the Sea became the first fully-animated film to be released on IMAX screens and proceeded to win an Oscar. The same year, Disney produced Fantasia 2000, the first full-length animated feature released exclusively in the IMAX format (the film would later have a conventional theatrical release). Disney would also release the first 2D live action native IMAX entertainment film, Young Black Stallion, in late 2003.

In the fall of 2002, IMAX and Universal Studios released a new IMAX-format of the 1995 theatrical film Apollo 13. This release marked the first use of the IMAX proprietary "DMR" (Digital Remastering) process that allowed conventional films to be upconverted into IMAX format. Other theatrically released films, would subsequently be rereleased at IMAX venues using the DMR process. Because of a technical limitation on the size of the film reel, these early DMR releases were edited to conform to a two-hour length limitation. Later releases did not have this limitation. Current IMAX platters allow a run length of up to 150 minutes. Some films, such as Star Wars Episode III: Revenge of the Sith, have been shown on IMAX screens using the standard 35 mm projection, but have not undergone the DMR process.

Reviewers have generally praised the results of the DMR blowup process, which have superior visual and auditory impact to the same films projected in 35 mm. Many large format film industry professionals point out, however, that DMR blowups are not comparable to films created directly in the 70 mm 15 perf IMAX format. They note that the decline of Cinerama coincided roughly with the supersession of the original process with a simplified, reduced cost, technically inferior version, and view DMR with alarm. IMAX originally reserved the phrase "the IMAX experience" for true 70 mm productions, but now allows its use on DMR productions as well. However, IMAX DMR versions of commercial Hollywood films are generally popular with audiences, with many people choosing to pay more than standard admission to see the IMAX version.

Since 2002 many other Hollywood films have been remastered for IMAX. Warner Brothers has especially embraced the format with the aforementioned Matrix sequels and since 2004 has been releasing its Harry Potter film franchise in IMAX to strong financial success. Also in 2004 the company also released the animated movie The Polar Express to IMAX in 3-D. Express became the most successful movie ever to be released in IMAX theaters, making at least a quarter of the film total worldwide gross of $302 million from less than 100 IMAX screens; because of its success, it has been re-released each holiday season since. In 2005 WB also released Batman Begins simultaneously in IMAX, which buoyed the film's strong legs helping it reach $200M at the domestic box office, and before the fourth Harry Potter film was released in IMAX format in November had claimed the record for most box office by a DMR movie. In summer 2006 WB released the highly anticipated Superman Returns remastered for IMAX and partially digitally transformed into 3D (director Bryan Singer chose the only four action scenes in the film to show in 3D). An IMAX exclusive film about the enormous, surprising success of the Mars Exploration Rovers was released in 2006, titled Roving Mars and used exclusive data from the Rovers. Spider-Man 3 broke the IMAX gross record in 2007 by a huge margin.

In 2008, the Rolling Stones released a concert film, Shine a Light,directed by Martin Scorsese, in IMAX format.

The July 2008 Batman Begins sequel The Dark Knight features six sequences shot using IMAX technology, which the movie's press notes describe as the "first time ever that a major feature film has been even partially shot using IMAX cameras".

Up to 2002, eight IMAX format films have received Academy Awards nomination with one win, the animated short, The Old Man and the Sea in 2000.

Many IMAX films have been remastered into HDTV format for the MOJO HD channel with limited commercial interruption. They can also occasionally be shown commercial free on HDNet and with limited commercials on HD Theater

Other Uses for IMAX

In July 2005 the BFI IMAX Cinema in London became the first to host live music concerts. IMAX theatre owners increasingly look to use the venue at varying times for alternatives to films.

The Science Museum London and BFI IMAX Cinema have also hosted computer game tournaments using digital projectors on the large IMAX screen. Other IMAX Theatres have also followed suit with game tournaments on their screens as well.

Technical specifications

IMAX (15/70)

• spherical lenses
• 70 mm film, 15 perforations per frame
• horizontal pulldown, from right to left (viewed from base side)
• 24 frames per second
• camera aperture: 70.41mm (2.772″) by 52.63mm (2.072″)
• projection aperture: at least 20.3mm (0.80″) less than camera aperture on the vertical axis and at least 0.016″ less on the horizontal axis
• aspect ratio: 1.34:1

IMAX Dome/OMNIMAX
Same as IMAX except:

• special fisheye lenses
• lens optically centered 9.4mm (0.37″) above film horizontal center line
• projected elliptically on a dome screen, 20 degrees below and 110 degrees above perfectly centered viewers

IMAX venues

Main article: List of IMAX venues

Gallery

• 
  Cinesphere,the world's first permanent IMAX theatre, at Ontario Place in Toronto, Ontario, Canada
• 
  L'Hemisferic (Ciutat de les Arts i les Ciències) Valencia, Spain
• 
  The black structure seen in this photo is the Luxor IMAX Theatre, situated in the Luxor Hotel

See also

• List of IMAX films
• List of IMAX DMR films
• List of IMAX-based rides

External links

• IMAX, the official Web site
• The-Numbers.com, IMAX box office figures
• [1], Bibliotheca Alexandrina Planetarium Science Center
• [2], Liberty Science Center: Home of the Nation's Largest IMAX Theater