The CAYOM Format and Camera Guide

[Xillix]

IMAX MEGAPOST 2021! PART TWO - TECHNICAL DETAILS!

 

What is the IMAX screen shape/aspect ratio?

Forgive me if this shakes you to your core, but IMAX does not now have, nor has it ever had, a standardized aspect ratio for projection. IMAX focuses on providing an image that fills as much of the audience's field of view as they can get away with and isn't terribly fussed with the specific shape, and their mass-market move into multiplexes has only exacerbated this. In the USA alone, the shapes of IMAX screens range from as wide as 2.18:1 to as tall as 1.17:1. They just install the biggest-looking screen they can squeeze in given the architectural constraints of the individual location. That also means the sizes of their screens vary hugely - from as high as 75 feet to as short as 23 feet. The only standard is that an IMAX screen, contractually, must always be the biggest screen in its multiplex.

 

However, the original IMAX film format has a maximum, full-frame aspect ratio of 1.435:1, variously stated either as the mathematically-correct 1.44:1 or 1.43:1 for... some reason. IMAX film projection is more or less dead now, but IMAX with Laser dual-4K projector systems are capable of projecting a full-height 1.44:1 image. But those systems are hard to find, and the overwhelming majority of IMAX locations use either the 2K IMAX Digital projection system or the single-projector variant of the 4K IMAX with Laser system, both of which have a maximum aspect ratio of 1.90:1. As such, most people now think of 1.90:1 as the "IMAX ratio," and it is usually the shape that is used when specially-formatted films feature an expanded image in IMAX presentations. Regardless of the projection system, though, only a handful of IMAX screens actually adhere to the 1.90:1 or 1.44:1 maximum ratios, and most need to either crop, letterbox, or pillarbox these images. That's why IMAX's advertising says "up to 26% more image" - there's a good chance you're not getting it all at your local IMAX.

 

A comparison of two IMAX screens, based on real-world measurements, with a 6 foot human to scale. Both use the same 2K projection system.
 

What are the details of IMAX's different projection systems?

 

IMAX 70mm Film

The original IMAX exhibition format, introduced in 1971 at the World's Fair in Osaka, Japan. More technically referred to as 15-perf 70mm film prints, or 15/70 for short. Based directly on the 15-perf 65mm negatives used for shooting in "real" IMAX on film, these gigantic film prints run horizontally through the projectors instead of vertically as in most systems. The film strips are 70mm high (including space for sprocket holes and the soundtrack), and each individual frame is 15 sprocket holes - or perforations, or perfs - wide. Like the film negatives, this gives IMAX film prints a maximum image area with an aspect ratio of 1.44:1. IMAX used to boast about how the theoretical equivalent resolution of an IMAX film print was ludicrously high, well above 4K, and many enthusiasts and purists still echo these claims, though real-world testing has never borne this out and IMAX shut up about that real quick once they went all-in on digital projection. Film does have a distinct "look" different from digital projection systems that many still prefer, though.

The last Hollywood film to be released in IMAX 3D on 70mm film prints was 2013's The Hobbit: The Desolation of Smaug. Since then, IMAX releases have only been made available in 3D digitally. The last reasonably wide release of a feature film on IMAX 70mm was 2014's Interstellar. Since then, the only features released on IMAX film prints - in very limited quantities - have been 2015's Star Wars Episode VII: The Force Awakens, 2016's Batman v Superman: Dawn of Justice and Rogue One, 2017's Dunkirk (37 film engagements worldwide) and Star Wars Episode VIII: The Last Jedi (11 film engagements in the US & Canada), a 2018 re-release of 2001: A Space Odyssey (5 film engagements in the US & Canada), and 2020's Tenet (8 film engagements worldwide).

 

IMAX Digital

IMAX Digital, introduced in 2008, is the primary form which IMAX takes today. It uses two side-by-side 2K (2048x1080) projectors to increase image brightness and allow projection on very large screens. There is no resolution boost from the use of two projectors. That was a step down from 70mm film in sharpness even in 2008, and the low resolution and lack of any HDR or deep-color capability means the system is really showing its age at this point.

 

One advantage IMAX Digital has at least over "regular" 2K digital projection is that IMAX allows use of the full 2048x1080 pixel area for image without having to adhere to the Scope or Flat DCI standard ratios, giving it a maximum image aspect ratio of 1.90:1. Most movies that have an expanded image in IMAX will expand up to this ratio, screen size and shape permitting.

 

IMAX Digital supports full-color 3D using linear polarization in projection and the 3D glasses. Unlike the more common circular polarization used by RealD, linear polarization means that if you tilt your head off-axis, the 3D effect falls apart as the glasses can no longer ensure that only one image is reaching each of your eyes. IMAX Digital also supports HFR projection, though IMAX likes to play their specs close to their chests so I can't say for certain what their specific HFR capabilities are. Peter Jackson's Hobbit trilogy was released in IMAX 3D at 48fps in select IMAX Digital locations.

 

IMAX with Laser - Dual Projectors

Intended for the largest, "traditional" IMAX screens and introduced in 2014, this uses a proprietary system of two side-by-side projectors with 4K resolution (4096x2160) and a laser light source that allows for HDR (high dynamic range) images with darker shadows, brighter highlights, and deeper colors. It's also capable of projecting a full-height 1.44:1 IMAX image in theaters with the screens to support it via an anamorphic lens.

 

IMAX with Laser supports full-color 3D via a different 3D system than IMAX Digital, involving color spectrum separation as opposed to polarization - the same tech used for Dolby 3D. It also maintains support for HFR projection, though that support is oddly limited - it maxes out at 48fps, and can only project HFR in 2K resolution, not 4K.

 

IMAX with Laser - Single Projector

The second, more common version of IMAX with Laser was introduced in 2018 and uses only a single 4K laser projector. Intended for installation in multiplexes and conversions of existing IMAX Digital auditoriums, it only supports the shorter 1.90:1 ratio and offers less potential image brightness than the dual-projector setup. It probably features the same 3D and HFR support as the dual-projector system, although I have not found solid confirmation that the specs are identical.

 

What are the details of IMAX's sound systems?

IMAX's basic surround system is nearly identical to the standard 5.1 surround layout, except that instead of a separate LFE channel, all of the speakers in the auditorium are full-range and can produce deep bass. There is also an extra height channel behind the screen near the ceiling.

Many IMAX auditoriums that are newer or have been converted to a laser projection system use IMAX's proprietary 12-channel sound layout. This, effectively, is IMAX's weird compromise between prior "3D sound" systems Dolby Atmos and Auro. It can't use each speaker individually the way that Dolby Atmos and (theoretically) DTS:X can. However, the layout is different than Auro's - it's got the same three front and four surround channels as a 7.1 system, plus the weird behind-the-screen height channel from standard IMAX audio, and four additional overhead channels aimed down at the audience from different spots on the ceiling, allowing sounds to move around above viewers, albeit with less nuance and precision than Atmos.

 

What are the technical details of IMAX film negatives and the IMAX certified digital cameras?

Check the first page! That's covered in the posts on cameras and film formats overall.

 

What is IMAX Digital Media Remastering (DMR)?

The majority of movies released in IMAX undergo what the company calls its "DMR" process, which they claim improves image quality with some vague series of sharpness and noise reduction tweaks. Originally it was used as part of the process for transferring movies shot on smaller film formats to be enlarged for IMAX film prints. Today it's just post-production processing done to a movie's digital master for release in IMAX theatres. Frankly it's almost definitely bullshit, and in fact Oscar-winning cinematographer Roger Deakins refused to allow his IMAX-released films Skyfall and Blade Runner 2049 to go through DMR because, after viewing tests, he felt it made them look worse.

Edited September 2, 2021 by Xillix

[Xillix]

 IMAX MEGAPOST 2021! PART THREE - USEFUL INFO FOR THE GAME!

How many IMAX screens or theatres are there? How many full-sized ones?

As of this writing (September 2, 2021), based on the latest data from LF Examiner, there are 401 IMAX screens in the US & Canada (the domestic box office market) that show commercial Hollywood films, as opposed to just IMAX documentaries. This includes screens which are temporarily closed as of this writing due to COVID-19, but are expected to reopen. These screens are in 398 separate venues, with four such venues - the Pacific Science Center in Seattle, Washington, and three Mega-Plex multiplexes in Quebec province, Canada - having two IMAX screens each that both show commercial films.

 

Of the 401 total IMAX screens:

349 rely primarily or entirely on the IMAX Digital 2K bulb-based projection system

39 rely primarily or entirely on the IMAX with Laser 4K single-projector system

36 allegedly still have IMAX 70mm film projection equipment, though this number is the most likely to be outdated

13 have the IMAX with Laser 4K dual-projector system
1 - at the McWane Science Center in Birmingham, Alabama - is an OMNIMAX dome theatre which isn't exactly suited to narrative films but shows them anyway; it uses the single-projector 4K laser system

 

39 can properly show a full-height 1.44:1 ratio IMAX image while using the full screen width:

   -27 can achieve this only with their 70mm IMAX film projectors

   -7 can achieve this only with their dual laser projectors

   -5 can achieve this with both film and laser projectors

 

For convenience, here is the list of those 39 screens in the spoiler below, along with their projection technologies and maximum uncropped image size:

Spoiler

FULL HEIGHT VIA 70MM FILM ONLY (MAY NOT HAVE 3D CAPABILITY):
Brenden Theatres at The Palms - Las Vegas, Nevada - 56 feet wide by 39 feet tall
Celebration Cinema Grand Rapids North - Grand Rapids, Michigan - 70 feet wide by 49 feet tall
Cinema Banque Scotia Montréal - Montréal, Québec, Canada - 82 feet wide by 57 feet tall
Cinema Cineplex aux Galeries de la Capitale - Québec City, Québec, Canada - 93 feet wide by 65 feet tall
Cinemark 17 - Dallas, Texas - 71 feet wide by 49 feet tall
Cinemark at Seven Bridges - Woodridge, Illinois - 70 feet wide by 49 feet tall
Cinemark Tinseltown USA - Rochester, New York - 70 feet wide by 49 feet tall
Cineplex Cinemas Langley - Langley, British Columbia, Canada - 70 feet wide by 49 feet tall
Cineplex Cinemas Missisauga - Missisauga, Ontario, Canada - 71 feet wide by 49 feet tall
Cineplex Cinemas Vaughan - Vaughan, Ontario, Canada - 72 feet wide by 50 feet tall
Esquire IMAX Theatre - Sacramento, California - 76 feet wide by 53 feet tall
Harkins Theatres Arizona Mills 18 - Tempe, Arizona - 80 feet wide by 56 feet tall
IMAX Theatre at the Indiana State Museum - Indianapolis, Indiana - 84 feet wide by 59 feet tall
Providence Place Cinemas 16 - Providence, Rhode Island - 81 feet wide by 56 feet tall
Regal Edwards Boise - Boise, Idaho - 70 feet wide by 49 feet tall
Regal Edwards Fresno - Fresno, California - 70 feet wide by 49 feet tall
Regal Edwards Ontario Palace - Ontario, California - 89 feet wide by 62 feet tall
Regal Hacienda Crossings - Dublin, California - 76 feet wide by 53 feet tall
Regal Pointe Orlando - Orlando, Florida - 85 feet wide by 59 feet tall
Scotiabank Theatre Chinook - Calgary, Alberta, Canada - 70 feet wide by 49 feet tall
Scotiabank Theatre Edmonton - Edmonton, Alberta, Canada - 70 feet wide by 49 feet tall
Scotiabank Theatre Halifax - Halifax, Nova Scotia, Canada - 72 feet wide by 50 feet tall

FULL HEIGHT VIA DUAL 4K LASER PROJECTION ONLY:
Boeing IMAX Theater at the Pacific Science Center - Seattle, Washington - 80 feet wide by 56 feet tall
Branson's IMAX Entertainment Complex - Branson, Missouri - 84 feet wide by 59 feet tall
Bullock Museum IMAX Theatre - Austin, Texas - 82 feet wide by 57 feet tall
The Palms Theatres - Waukee, Iowa - 86 feet wide by 60 feet tall
Scotiabank Theatre Toronto - Toronto, Ontario, Canada - 78 feet wide by 54 feet tall
Sunbrella IMAX Theatre at Jordan's Furniture Reading - Reading, Massachusetts - 84 feet wide by 59 feet tall
Tennessee Aquarium IMAX Theater - Chattanooga, Tennessee - 87 feet wide by 61 feet tall

FULL HEIGHT VIA 70MM FILM (POSSIBLY 2D ONLY) AND DUAL 4K LASER PROJECTION:
AMC Lincoln Square 13 - New York City, New York - 101 feet wide by 70 feet tall
AMC Metreon 16 - San Francisco, California - 98 feet wide by 68 feet tall
AutoNation IMAX Theater at the Museum of Discovery and Science - Fort Lauderdale, Florida - 80 feet wide by 56 feet tall
Cinesphere Theatre at Ontario Place - Toronto, Ontario, Canada - 80 feet wide by 56 feet tall
Universal Cinema AMC at CityWalk Hollywood - Universal City, California, 79 feet wide by 55 feet tall

 

An additional 3 screens have film projectors and screen aspect ratios significantly taller than 1.90:1, and can show part of the additional image of a 1.44:1 release while using the full screen width if using the film projectors. They are listed below in the spoiler along with their maximum possible image sizes and how much of the image is cropped to fill the screen:

Spoiler

PARTIAL EXPANDED RATIO FOR 1.44:1 IMAX VIA FILM PROJECTION (MAY NOT HAVE 3D CAPABILITY):
PACCAR IMAX Theater at the Pacific Science Center - 58 feet wide by 35 feet tall - 1.68:1 ratio (15% crop from 1.44:1)
Regal Lone Star - Tomball, Texas - 71 feet wide by 45 feet tall - 1.58:1 ratio (9% crop from 1.44:1)
Regal UA Colorado Center - Denver, Colorado - 71 feet wide by 42 feet tall - 1.69:1 ratio (15% crop from 1.44:1)

 

The other 359 screens are only equipped with either the 2K digital projection or single-projector 4K laser systems, both of which have a maximum image ratio of 1.90:1, even if their screens are much taller.

 

LF Examiner has a website with a browsable database of IMAX theatres, technical details and screen measurements. You can find it here: https://lfexaminer.com/theaters/

 

I also keep a spreadsheet with this information for US & Canadian theatres, and you can PM me if you have questions and can't be bothered to look them up yourself.