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. A standard IMAX
screen is 22m wide and 16.1m high (72.6ft x 52.8ft), but can be larger. Currently, 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 percent of
these are located in the United States and Canada). Half
of these are commercial theatres and half are in educational venues. The biggest "IMAX Dome" is in the Liberty Science Center in Jersey City, New
Jersey. 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.
Precursors
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 joints between the screens were difficult to hide.
History
The IMAX system was developed by four Canadians: Graeme Ferguson, Roman Kroitor, Robert Kerr and William C.
Shaw. [1]
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 very much in use, as it is situated 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[2], 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 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. 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. Mr. 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 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.
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 likely to 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.
Another use of IMAX Dome technology is to provide an immersive visual experience to go with a ride simulator, as in
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
An IMAX 3D camera.
To create the illusion of 3-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 about 64 mm/2.5 in., 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 very cumbersome, weighing over 113
kg/250 pounds. This makes it extremely 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 in Prasads IMAX located in Hyderabad,
India.[3]
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, but 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 their theme park ride 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.
Viewer experience
For the viewer, these technical differences result in a more immersive, engaging experience than conventional film projection.
The large screen and close seating mean that much of the viewer's field of vision is
filled with the image, and the high resolution and positional stability of the film format imparts a sense of reality and detail.
IMAX film can be overwhelming at times, with some viewers experiencing motion sickness
during scenes with significant motion, especially if the action cuts between moving and still scenes. One of the movies that
caused this effect was the 3D version of Superman Returns, since the 3D scenes
were spread throughout the film. Current 3D adaptations of popular movies have the 3D scenes all at once, such as
Harry Potter and the Order of the Phoenix. In
scenes where the motion on the screen moves downwards, a "free-fall" sensation is felt (like going down on a roller coaster).
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.[citation needed]
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, which had a successful run in 1998 and Haunted
Castle, released in 2001 (both of these were IMAX 3-D 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 2-D 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 Re-mastering) process that allowed conventional films to be "up" converted into IMAX format.
Other theatrically-released films, would subsequently be re-released 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. It was previously reported
that Star Wars Episode III: Revenge of the Sith was
released with an IMAX DMR version, however it never underwent the DMR process. Venues that showed this film in an IMAX screen
used standard 35 mm projection.
In 2003 a notable IMAX re-release, again using the DMR process, was The Matrix
Reloaded. Later in 2003, the sequel The Matrix Revolutions was
the first live action film to be released simultaneously in IMAX and conventional theaters, the first feature film being
Treasure Planet.
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. In 2005 WB also released Batman Begins simultaneously in IMAX,
which buoyed the film's strong legs helping it reach $200 m 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 four action scenes in the film to show in
3D). The film was a disappointment at the box office in light of its huge budget and perceived large fanbase. 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.
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
INHD channels.
Other Uses for IMAX
In July 2005 the BFI IMAX Cinema in London
became the first to host live music concerts. IMAX theater 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: 70.41 mm (2.772″) by 52.63 mm (2.072″)
- projection aperture: at least 20.3 mm (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 9.4 mm (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
The black structure seen in this photo is the Luxor IMAX Theater, situated in the
Luxor
Hotel.
-
Notable IMAX venues include:
- The Cinesphere at Ontario Place in
Toronto, Ontario, Canada – the first permanent IMAX
theatre.
- IMAX in Canada Place in Vancouver,
British Columbia, Canada – the first IMAX 3D theatre.
- Futuroscope, France – theme park, only place containing
all versions of IMAX theatres. (Normal, Dome, 3D, 3D Dome ("Solido") and IMAX Magic
Carpet.)
- The Reuben H. Fleet Science Center in San Diego, California, USA – the first IMAX Dome installation.
- Liberty Science Center, Jersey
City, New Jersey - the largest IMAX dome theatre in the world.
- LG IMAX, Sydney, Australia, the largest cinema screen in
the world.[1]
- Prasads IMAX in Hyderabad, India - the world's largest 3D-IMAX and India's 3rd IMAX theatre.[4]
References
External links
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