Tech InDepth: Understanding IMAX and what makes it so good

If you’ve ever been to an IMAX movie, you likely need no introduction on how different the experience feels compared to watching the same movie on a regular cinema screen. IMAX screens are bigger than most conventional cinema screens, but there’s also a lot more to it than just the size.
In today’s edition of Tech InDepth, we will be looking at the technology that goes behind IMAX screens and how it changes the experience for viewers, in terms of visuals and acoustics.
Let us begin with the basics.
What is IMAX?
IMAX is a standard of high-resolution cameras, film formats, projectors and yes, cinemas. The name is believed to be derived from “Maximum Image” which is quite fitting given how much . IMAX movie screens are known for their instantly recognisable tall aspect ratio, which is usually 1.43:1 or 1.90:1. These screens also feature steeper stadium seating in the cinema hall itself, which lead to a better audio experience.

When one refers to an IMAX screening of a particular movie, there are multiple layers of technology used, both in the film-making process as well as the viewing aspect of it. What this means is for a movie to be enjoyed in true IMAX, it needs to be screened on an IMAX-specification screen and also shot on high-res IMAX cameras.
IMAX cameras
IMAX movies are shot using cameras that can record using a larger frame, usually three times the theoretical horizontal resolution of a conventional 35mm film. These cameras are capable of capturing footage with a very high amount of detail and clarity.
Popular IMAX cameras include the Arri Alexa LF and Arri Alexa Mini LF, both of which are 4K cameras. There is also the Arri Alexa 65 camera (6.5K camera) that was used to shoot movies like Captain America: Civil War, Avengers: Infinity War and Avengers: Endgame.
IMAX uses special cameras to shoot, which capture footage at high resolutions. (Image Source: IMAX)
Others include Sony’s Venice cameras (6K), Red Ranger Monstro (8K) and the Panavision Millennium DXL2 (8K). For 2017’s Transformers: The Last Knight, two ARRI Alexa IMAX cameras were combined in a rig to provide native 3D. The final film contained 93 per cent IMAX footage.

It doesn’t end at shooting on high-res cameras. IMAX also processes the captured footages and uses proprietary image enhancement through every frame in a movie, allowing you to see the clearest and sharpest picture quality, closest to what the movie’s director wants you to experience. DMR or Digital Media Remastering is also used to scale traditional 35mm films to IMAX. Popular examples of this are the IMAX re-release of 1995’s Apollo 13 or Star Wars: Episode II – Attack of the Clones.
IMAX projectors
Once the footage is captured and the movie is edited using powerful software, you still need the right projectors to operate the movie at a theatre near you. IMAX uses two variations here – the digital projection system and the laser projection system.
Digital projection is used for shorter 1.89:1 aspect ratio screens. It implements two 2K projectors that can project 2D/3D content. Output from these two projectors superimpose upon each other perfectly to create the visuals we see during an IMAX movie.
IMAX commonly uses uses twin projectors to get a better overall image quality in the cinema. (Image Source: IMAX)
Laser projection is used for both 1.43:1 aspect ratio and the wider 1.89:1 aspect ratio. The newer system, which has been in development since 2012, replaces the xenon arc lamp of a traditional digital projector with a laser light source.
This translates to visuals with almost 50 per cent more brightness and twice the contrast ratio compared to digital projection systems. Also, laser projection supports 60fps.
IMAX Audio
We don’t probably give this enough thought, but half the experience of any movie in a cinema is the audio. For the IMAX standard, sound isn’t just about being loud and clear, but a lot more. IMAX delivers a very high dynamic range of sound, which means that the lowest whispers in a horror movie can be heard with extreme precision while an impactful soundtrack in the same film can be just as powerful.
IMAX also uses unique designs in its theatres along with materials on the wall surfaces. These are capable of absorbing unwanted sound from the audience while enhancing sound from the movie.
IMAX audio is designed to provide a wide dynamic range and a uniform experience to everyone in the theatre. (Image Source: YouTube/ IMAX)
The IMAX screens also use custom loudspeakers and subwoofers, with the latter being able to go as low as 23Hz comfortably while a traditional system can go down till about 40Hz frequency. The loudspeakers which are hand-built also use a technology called PPS (Proportional Point Source technology) which allows people sitting close to the speakers to get the same experience as others sitting closer to the centre.

Theatre and seats
Finally, IMAX puts all of this together to create a completely customised environment that is designed to enhance your experience. This includes seats spaced away from the screen just enough to open your eyes to a 70-degree FOV (field of view). Every single seat is also positioned accordingly to get the same experience, which is why you will see seat-rows curving from end-to-end in some larger IMAX screens.
Now that you know how much time, effort and technology goes behind an IMAX screening, you’ll be able to enjoy your next movie even more.