IMAX CONTENTS

S.no. TITLE PAGE NO.

1. Abstract

2. Introduction

3. What is an IMAX

4. History of IMAX

5. Technical aspects

5.1 Intent

5.2 The Lens

5.3 The Projector

6. Sound in IMAX

6.1 Dome

7. Applications of IMAX

7.1 IMAX 3D

7.2 IMAX HD

7.3 IMAX Digital 3D

7.4 Technical Specifications

8. Conclusion

Abstract:

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 DOME (originally called OMNIMAX), is designed for projection on tilted

dome screens. Films can also be projected in 3D with IMAX 3D. 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 Sydney, Australia.

Introduction:

The difference between the IMAX sound system and the surround

systems in conventional theaters is that the typical IMAX screen is close

to a conventional 4:3 aspect ratio, but much, much bigger. So you have

a great deal of vertical, which gives you the opportunity to do a 'voice-

of-God' loudspeaker. IMAX system power varies depending on the size

of the room, but it is typically in the range of 12,500 watts. The power is

not there for the loudness; it's there for clarity and freedom from

distortion. The enclosures are three-way systems using components

custom-designed and manufactured to specifications and combines

four low-frequency loudspeakers in each cabinet with nested high- and

mid-frequency horns.

What is an IMAX:

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 22 meters (72 ft) wide and 16.1 meters (53

ft) high, 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.

History :

The IMAX system was developed by four Canadians: Graeme Ferguson,

Roman Kroitor, Robert Kerr and William C. Shaw. During Expo ‘67 in

ontreal, Quebec, 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

eatured 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 nouncement

of an SEC investigation, falling again when the announced third quarter

earnings were behind the previous year's.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.

Technical aspects:

Intent:

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.

The lens :

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 pressed

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

automatic 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.

The projector:

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-

hickness 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.

The sound in IMAX:

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 riginal

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. speakers directly behind the

Many IMAX theaters place screen as well as distributing the speakers

around the theater to create a three-dimensional effect.

The Dome:

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 ome

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 orizontally

, 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

MNIMAX 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. While the majority of

OMNIMAX theaters in museums focus on educational and documentary

films, on special occasions, as with the release of Charlie and the

Chocolate Factory at the Oregon Museum of Science and Industry,

major studio releases are also shown. 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.) 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.