Immersive Picture and Sound: Immersive Format: Dolby Vision
Dec 29, 2014 10:57 AM, By Jon Silberg
Filmmakers who have worked with Dolby’s High Dynamic Range (HDR) Vision format say they notice a higher contrast range, with more detailed, brighter highlights and shadows, and more scale in between.
As stakeholders and standards organizations continue to expand visual storytelling and sell new display technology, the discussions have focused mostly on resolution—spatial resolution, as in 4K, 8K and beyond, or temporal resolution as in high frame rate (HFR) of 60p or greater. A third way to increase the amount of image detail is high dynamic range—which we’ll call HDR, even though other names, such as extended dynamic range have been used.
Dolby, through its Dolby Vision product, is among the companies most advanced in developing HDR video technologies. People in various aspects of production and post have viewed material mastered for Dolby Vision on the company’s prototype monitor and many have reported significantly increased contrast range, more detailed and brighter highlights, as well as shadows, more pronounced differences throughout the gray scale and wider color gamut.
Dolby Vision refers to HDR mastering and display approaches proprietary to that company and for the moment its nuances can only be perceived on Dolby monitors. So interestingly, Dolby is a potential leader in the future of display technology. The company is in talks with TV manufacturers to employ the Dolby IP in hardware in future televisions. This would allow material mastered to Dolby Vision specs to be presented accurately on the Dolby monitors now, while the TV industry gradually develops consumer sets capable of displaying the super bright whites. (At the moment, there is no practical, energy efficient way for a TV that could sell at Best Buy to come close to taking full advantage of content mastered to Dolby Vision specs, so the roll-out must be incremental).
For cinema screens, Dolby recently announced a deal with Christie, to offer the theatrical version of Dolby Vision. Two Christie 4K laser projection heads used in tandem put out the necessary brightness needed to display HDR on multiplex screens; with this system a theater can display 3D content at the standard 2D brightness level of 14 foot lamberts and 2D content at an impressive 31 foot lamberts.
Among those involved in HDR testing is former Disney technology executive Howard Lukk, who decided to make a live-action short, Emma, with HDR. Produced by Pannon Entertainment’s Andrea Dimity, Emma was designed to work within the dynamic range of current HD display and theatrical projection, but also to benefit from HDR.
“We picked dark colors that other productions avoid,” Dimity said. “We have a dark car in low light with bright taillights. It’s the kind of situation that filmmakers would either stay away from or use lighting techniques so the differences from light to dark aren’t so extreme. But this was exactly the kind of scene our cinematographer, Daryn Okada wanted to experiment with.”
Lukk said, “We will still be able to make the scenes work with traditional displays but we’ll have to do what you always do in the color grading process and tone map the images to ‘fit’ within the contrast range of the display. So you always either ‘flatten’ them out a bit or you use windows to bring particular portions into the range that you’re going to be able to display. For Emma, we also did a second grading pass that can take advantage of a higher dynamic range display.”
It is important here to make a key distinction between the HDR display and HDR image capture. The latter is an expression of how many stops of information a sensor (or piece of film neg) can record. Cameras such as the ARRI Alexa, Sony F65 and Red Epic boast advances in dynamic range through sensor and processing technology. But when those images are mastered for display, they all still need to be tone mapped to “fit” into the dynamic range of the display. This will still be the case no matter what the dynamic range is of the display.
Mankind may never see a panel that can display the true brightness of the Sahara Desert at noon, but a higher dynamic range gets us that much closer than today’s HD spec and therefore gives us images that look closer to reality.
Dolby has developed monitor technology to display images at a wider color space and greater bit-depth than the .rec 709 standard. Companies including Adobe and color corrector manufacturers FilmLight and SGO, among others, have embraced Dolby Vision technology, as have Netflix, Amazon and other content distributors.
On the TV set side, manufacturers, including Sharp and TCL are also working with Dolby Vision as the technology develops. At this point it is not clear to what extent the .rec 2020 (UHD) spec would be involved.
Although Dolby plans to sell their IP to set manufacturers, they have in the meantime built a prototype monitor themselves. The proprietary processing technology, “will soon be available to manufacturers to enhance the contrast ratio of their displays,” said Roland Vlaicu, Dolby Laboratories vice president of Consumer Imaging. “It is important not just to make displays better but to make the signal going into the displays better than that 20-year-old .rec 709 signal that is limited to 8-bits [per channel] and has such low fidelity in terms of dynamic range and color.
“We are working on this HDR concept by changing the delivery mechanism itself,” Vlaicu said. “We are building an entire ecosystem, similar to what we’ve done with surround sound audio.”
While he admits that it would be completely impractical for any manufacturer to attempt to mass produce a display with the dynamic range of Dolby’s very power-hungry prototype monitor, Vlaicu emphasized that future developments could change that. Furthermore, Dolby Vision is designed to be scalable so that a TV with less dynamic range than their prototype but significantly more than today’s HD panels, could ingest the images mastered for the highest dynamic range and tone map it on the fly (through internal circuitry designed by Dolby) to work for that screen.
This scalability could allow programming mastered for the highest possible display dynamic range to provide the benefits of increased display dynamic range—say on next year’s sets, or on the multiplex screen in two years. That same signal could make use of the even greater dynamic range in three years if and when newer, more efficient and powerful light-emitting technologies are available.
Dolby is taking a chance on playing an aggressive, disruptive role in the future of imaging capture and display. The company is taking their case to display manufacturers, standards bodies, and content creators in a hands-on way, deploying working prototypes that are practical now, and building consensus for a longer-term play.
WHAT IS DOLBY CINEMA?
Last month Dolby and Christie Digital announced Dolby Cinema, a branded premium cinema offering that delivers a turnkey theater optimized for image, sound, acoustics, and design. As envisioned by Dolby, Christie, and multiplex partner JT Cinemas, the experience starts with a custom entrance (pictured) designed to signal that audiences are entering into a signature experience, much like the way a theme park attraction starts at the door. Inside, the theater is designed as an optimized sound and imaging environment. The sound side deploys Dolby’s immersive, dynamic Atmos format, in this case played back through Christie’s Vive Audio Class D amps and speakers. On the picture side, the projection system co-developed with Christie seeks to maintain the contrast, high brightness and color range that many filmmakers have identified as characteristic of the Dolby Vision format. The projection system employs new proprietary HDR technology for enhanced color processing, Christie’s 6P modular laser light sources, and two newly designed HFR-capable 4K laser projection heads with a unique light path. The resulting spec is up to 14 foot lamberts in 3D and up to 31 foot lamberts for 2D Dolby Vision content--numbers that quite dramatically exceed the current industry standard for ultra-brightness. The first Dolby Cinema sites will be located at the newly constructed JT Cinemas complex in Eindhoven, Netherlands, and the UCI/Cinesa La Maquinista complex in Barcelona, Spain.