What is Dolby Cinema?

"Yes, the projector is still on..."

by Steve Withers Aug 31, 2016 at 9:44 AM

  • It would seem that Dolby aren't content with just revolutionising the television industry at the moment, they plan to do the same at your local multiplex.
    Dolby Cinema is a premium cinema concept created by Dolby Laboratories, that is intended to bring movie houses into the 21st century through a combination of cutting-edge but uncompromising design, high dynamic range and immersive audio. Dolby Cinema is designed to be nothing short of the perfect cinema-going experience, from the moment you buy your ticket until the last credit has rolled. Dolby Cinema combines proprietary technologies like Dolby Vision and Dolby Atmos with signature entrance and intrinsic design features. These new cinemas are designed to compete with other premium large format systems like IMAX.
    Your Dolby Cinema experience will begin as soon as you arrive outside the auditorium, with a specially designed and branded entrance that uses a curved video wall entrance displaying content related to the feature film you are about to see. This content is specifically generated by the film studio and is intended to immerse viewers in the movie experience before the film has even started. This theme is extended as you walk down the corridor leading into the actual auditorium, with film-related content displayed on the side walls. The video is generated using multiple short throw high definition projectors in the entrance and corridor ceilings, using proprietary software to pixel map the different images together along the walls. similarly, the audio is generated using speakers placed in the ceiling of the entrance and corridor.

    Once in the cinema itself, the first thing you'll notice is that the entire auditorium is black – the walls, the ceiling the floor and the seating – this is to maintain the superior contrast performance of their laser projectors. As anyone who has ever built their own home cinema will know, the darker you can make the environment the less reflected light on the screen and the better the contrast of the projected image. We've never understood why so many professional home cinema installations have light coloured walls because that ruins the projected image. If you want the contrast performance of your projector to be optimal, make the viewing environment as dark as possible. In Dolby's case the only light in the auditorium will be the legally mandated exit signs and the reflections off the audience themselves. There's nothing the company can do about the first and, aside from issuing everyone black clothes and balaclavas as they walk into the cinema, there isn't much they can do about the latter either.

    The other important aspect to the design of the auditorium is ensuring that all the speakers, and there are a lot of them, can't be seen. This is an important element in creating a transportive and immersive sound experience. By making the auditorium completely dark and ensuring the speakers can't be seen, the walls and ceiling simply disappear, and instead the audience is surrounded by the environment of the film. It's another useful tip for anyone designing their own home cinema and if you can hide the front speakers behind an acoustically transparent screen and use in-wall and in-celing speakers or simply hide them behind black acoustically transparent material, the effect can be quite remarkable. Dolby might well be applying their design ethos to professional cinemas but it's an uncompromising and highly sensible approach. It is also an approach that is equally as applicable in the domestic environment, so if you're designing a dedicated home cinema – hide the speakers and make it black!
    The dual 4K laser projector system supports Dolby Vision with high dynamic range and a Rec. 2020 colour gamut
    After designing the perfect auditorium in which to watch a movie, Dolby then moved on to developing the best possible projected image. The biggest weaknesses of any projected image are the black levels and contrast ratios because if you are physically taking the light from a bulb and shining it through a piece of film or reflecting it off an imaging chip then the absolute level of black is inherently limited. Under Digital Cinema guidelines, a cinema image should have a brightness of 14-16 foot-lamberts and a contrast ratio of around 2,000-2,500:1. Dolby have developed an in-house projection system in conjunction with Christie Digital that is based around Dolby Vision and dual laser projectors.

    The system consists of dual Christie 4K primary colour laser projectors featuring a customised design developed by Dolby themselves. The system is capable of a level of performance far in excess of traditional projectors with xenon bulbs and when using both projectors in 2D the system is capable of delivering 31 foot-lamberts. The ability of the laser projectors to deliver absolute black, combined with the completely blacked-out auditorium, means that the system can also deliver a vastly superior contrast ratio that Dolby rate at 1,000,000:1.

    The increased brightness of laser projection is important for another reason as well, it allows films to be graded in Dolby Vision for theatrical presentation with High Dynamic Range (HDR). A Dolby Vision grade for a theatrical presentation can deliver a peak brightness of up to 108 nits for 2D and 48 nits for 3D thanks to the laser projectors. This means that cinema-goers can enjoy an HDR experience in much the same way as they can at home with a Dolby Vision television; although Dolby Vision for TV, with its much higher peak brightness, is currently graded at 4,000 nits.

    Dolby Vision uses the standard D65 colour temperature for white but thanks to the use of lasers it is capable of delivering a wider colour gamut that can get to Rec. 2020, which is much bigger than the DCI-P3 standard used for normal digital cinema projection. This means that when grading films in Dolby Vision for a Dolby Cinema release, the colourist has the option to push the colour gamut wider than DCI-P3, something that was done for both Inside Out and The Jungle Book. The projectors can also handle Higher Frame Rates (HFR) should that be necessary, although HFR hasn't really made much impact in the filmmaking community to date.

    Finally the increased brightness of the dual laser system also allows for a superior 3D experience when compared to a normal DCI bulb-based projector. Unlike at a regular cinema, where the recommended brightness is around 4 foot-lamberts, in a Dolby Cinema it is 14 foot-lamberts. This significantly higher brightness also allows Dolby to use a unity-gain (1:1) matte-white screen, as opposed to the highly reflective silver screens used in regular cinemas, and as result there is absolutely no hot-spotting. There is also absolutely no crosstalk thanks to the dual laser projectors and wavelength multiplex glasses, which filter using the wavelengths of the three primary colours rather than polarising filters, thus producing more accurate colours.

    The final aspect in Dolby's quest for the perfect projected image is the use of a constant height screen. That means the screen is the width of the auditorium and uses an aspect ratio of 2.35:1. When projecting films made in a 1.85:1 aspect ratio there is masking at the sides but when switching to a widescreen film the projector zooms, shifts and refocuses to the full width of the screen and the side masking moves out to reveal the 2.35:1 aspect ratio. There is nothing that says cinema better than watching side masking move out to reveal a full 2.35:1 widescreen image and, once again, it's a philosophy that translates to home cinemas as well. If you have the space and budget for a constant height 2.35:1 screen and side masking, along with a projector with a lens memory, it is well worth considering.
    The final element in Dolby's ambition to create the ideal cinema experience is the part of the film-viewing experience they are most famous for – sound. Dolby has become synonymous with film sound over the last fifty years, so it's no surprise to discover that a Dolby Cinema boasts the very latest in immersive audio technology. Dolby Atmos is an object and channel based hybrid sound format developed by Dolby, initially for the cinema but it is now also available for home use. The cinema system is capable of reproducing ten bed channels and 128 objects, through 64 individual speakers in order to seamlessly pan sound around and through the auditorium. There are four subwoofers, one in each corner, speakers behind the screen, speakers that run from the screen all the way along the side walls and the rear wall and two arrays of speaker that go overhead.

    As mention previously all these speakers are hidden from view, so as not to ruin the illusion of being completely immersed in the film's soundtrack, and the auditorium is acoustically treated to ensure the optimal sound quality. Dolby Atmos allows recreation of effects such as thunder or flyovers thanks to the ceiling channels, whilst the object-based approach allows for pinpoint effects like bullets to be positioned precisely within a 360º sound field. Dolby Atmos is of course used by many cinema chains these days but it's the combination of uncompromising design, Dolby Vision and Dolby Amos that makes Dolby Cinema such a unique experience. The filmmaker's intent is perfectly replicated in terms of both image and sound, whilst the overall experience is both compelling and utterly immersive.
    Dolby Atmos uses ten bed channels and 128 objects with 64 individual speakers to seamlessly pan sound throughout the auditorium
    Of course as impressive as all this technology is, the real question what is the experience like in practice? We recently visited Dolby's private screening room in the their Soho Square offices and were lucky enough to have a one-on-one demonstration of Dolby Cinema with Nick Watson, their Technical Director for Content Relations. Since the screening room is private and not intended for the public, there is no signature entrance or video wall as you enter and the speakers are visible but aside from that it is a fully specified Dolby Cinema. We took a seat in the sweet spot, centre of the screen and half way back and settled down for a truly remarkable experience.

    The demonstration started with a representation of a normal projection experience based on a regular bulb-based projector. So there was a black screen with a white circle in the middle and the white circle was 14 foot-lamberts and the contrast ratio was around 2,500:1. The image looked good but clearly the blacks were more of a very dark grey and the white circle didn't exactly pop. Then the image switched to the full potential of the dual laser projector system and immediately the blacks were truly black and the white circle was now 31 foot-lamberts and really popped off the screen. Suddenly that 1,000,000:1 contrast ratio seemed quite realistic and when projecting a completely black screen, you understood why Dolby use the tagline "yes, the projector is still on." The nature of a projected image means there will always be small amount of light reflected off the screen but these were still the deepest blacks we have seen projected anywhere.

    After that the demo moved on to two scenes from The Revenant; the first was from the start of the film as Leonardo DiCaprio is hunting in the woods and the combination of the Dolby Vision image and the Dolby Atmos soundtrack completely immersed the viewer. The detail in the native 4K image was staggering, whilst the light shining through the leaves was realistically bright and the shadows among trees retained all their detail. The colours were wonderfully realistic and the sounds of the forest surround the viewer, placing you right next to DiCaprio's trapper. The next scene showed a search party moving through a wood at night, their flaming torches the only source of illumination. The Revenant was famously shot almost entirely with natural light and this sequence really showed the full potential of HDR, laser projection and Dolby Vision.

    After that we moved on to a scene from Batman v Superman: Dawn of Justice which was shown in 3D. The brightness of the 3D was incredible, it was like watching a 2D film in a normal cinema. There was no hot-spotting or crosstalk and the colours appeared completely natural. Zak Snyder's deliberately contrasty visuals certainly lent themselves to Dolby Vision and the brightness of the policeman's torches in one scene really showed the impact of Dolby Vision. The increased resolution meant that it was obvious when a scene switched between 35mm and IMAX footage during the battle between Batman and Superman. The soundtrack was simply thunderous, hammering the viewer into submission with incredible bass and immersive effects. The only issue we had was that because the image is so much brighter we were getting reflections inside the 3D glasses as light bounced off our eyelids and cheeks. Dolby are aware of the issue and the company is working on a solution.

    The next scene was from Inside Out and this time it demonstrated how the animators at Pixar deliberately widened out the colour gamut in the Dolby Vision grade in order to make a certain scene appear more saturated and dreamlike. The affect was quite noticeable, with the combination of Dolby Vision and Dolby Atmos adding greater impact to the emotion of the scene and supporting the filmmaker's intentions. We then watched a sequence from The Jungle Book in 3D and were hugely impressed by the animation, the detail, the dynamic range, the sound mix and the 3D, it was quite simply a technological tour-de-force. The quality of images that we can watch at home is improving exponentially at the moment but this demo of Dolby Vision and Dolby Atmos proved that the cinema-going experience isn't standing still either.

    So far there have been 53 films graded in Dolby Vision and mixed in Dolby Atmos for a Dolby Cinema release, stating with Tomorrowland and leading up to recent titles like Captain America: Civil War. The only real problem is actually getting to visit a Dolby Cinema. Although there are currently 32 locations in the US, Europe and China, sadly there are none in the UK yet to compete with IMAX Laser. Hopefully that will change soon and everyone in the UK will have the opportunity to visit a state-of-the-art Dolby Cinema and experience picture and sound that perfectly compliments the filmmaker's creative intentions

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