HDR displays have made video with the full tonal quality and brightness perceptible to the human eye a practical reality. CREDIT: Dolby.

(VANCOUVER) The glitzy CES 2014 – the world’s largest consumer electronics tradeshow – saw the unveiling of Dolby’s new High-Dynamic Range (HDR) imaging technology. Dubbed “Dolby Vision,” the experimental 1080p liquid-cooled display gave the public a dazzling preview of how HDR can bring video vividly to life. Thousands of tiny light-emitting diodes (LEDs) inside provide unparalleled contrast and crisp brightness to deliver a picture quality that matches real-world visual perception of depth, detail, and color.

The result is a dramatic improvement to image quality that arguably tops the extra resolution of new 4K UHD (Ultra-High Definition) TVs. Compared to the contrast ratio for a good flat-panel LCD of around 1,000:1 (the range between the lightest and darkest points on the screen), current HDR display technology offers a range of over 1,000,000:1, at 40 times the brightness of conventional TV - producing video images with the full tonal quality and brightness perceptible to the human eye.

Dolby Vision’s debut marks a commercial breakthrough for pioneering Canadian research that began over a decade ago and inaugurates an entirely new generation of display technology.

HDR displays emerged out of the rapidly growing field of computational photography. Intersecting computer graphics, machine vision, imaging, inverse methods, optics, and human perception, computational photography aims at improving on traditional digital images by optically encoding information about the real world.

“Unlike in traditional photography, computational photographs are not necessarily intended to be directly interpreted by a human observer. Instead they represent detailed information such as scene geometry, motion of solids and liquids, multispectral information, or high contrast (high dynamic range), which can then be computationally decoded.” explained Dr. Wolfgang Heidrich, a UBC computer science professor in GRAND who played a key role in developing the first HDR display.

Computational displays, likewise, decode these enhanced images using software jointly designed with the hardware (optics and electronics) to produce compelling visual experiences. The design furthermore takes into account what we know about human perception to reproduce those aspects of an image that make a difference to the visual experience of the viewer.

“The HDR display was one of the first technologies to successfully demonstrate this principle, both from an academic perspective and as a commercial application. Since then, the principle has inspired several important developments that are still in the early stages of commercialization, but show great promise.” noted Dr. Heidrich, citing examples such as glasses-free 3D displays and displays with spatial and temporal super-resolution.

Following adoption by leading manufacturers, televisions and monitors enhanced with Dolby Vision are expected to hit store shelves by the end of 2014, more than a decade after the initial research breakthroughs.

Interdisciplinary team behind HDR technology

The core technology arose from a prototype design created by UBC physicist Dr. Lorne Whitehead who had initiated and led a research program boasting a broad technology portfolio.

The first key patent arose from collaboration between himself, his student Helge Seetzen, Lawrence Berkeley, laboratory computer scientist Greg Ward, and York University computer science professor and GRAND researcher Dr. Wolfgang Stuerzlinger. Dr. Whitehead credits the research environment at UBC with enabling this development, which eluded researchers elsewhere in the world. 

“It wasn’t that any one aspect of our HDR solution is particularly difficult to understand once it’s described – the challenge was that the various insights we combined came from very different fields, between which traditionally there had been limited collaboration,” explained Dr. Whitehead. “Our success was assisted by UBC’s encouragement of interdisciplinary collaboration.”

Prior to HDR, the only way to extend the dynamic range of video images – the maximum range between the darkest and brightest parts – was through a process called “tonal mapping,” which fits the image data to the capabilities of the display. Standard displays, however, fall short of recreating the vast dynamic range of colours and contrasts that we experience in our daily environment. The dynamic range of the human eye spans from starlight to sunlight over at least an eight-orders-of-magnitude luminance range. Most displays cover a far narrower range. The result for the viewer is toned-down images that lack the vitality, depth, and realism of actual vision.

To make digital images look the same as in the real world required a significant expansion of the contrast or dynamic range of the display. To also make the new system commercially viable it had to fit within the current hardware and software infrastructure and market price points.

Building on this foundational work, Dr. Whitehead and the UBC Liaison Office solicited business investment and launched the UBC spin-off company Brightside Technologies (originally Sunnybrook Technologies) to devise a way to dramatically boost the dynamic range of LCD displays with off-the-shelf components. With Helge Seetzen as its CTO, Brightside continued to improve on the basic UBC design: two overlapping displays – one, a transparent LCD panel used as an optical filter to control a second high-intensity but low-resolution LED display. Demonstrations produced a dynamic range far beyond any commercially available video technology. 

A growing international body of expert consultants aided this development. Eventually, computer scientist Greg Ward joined the HDR commercial effort. Later, Dr. Wolfgang Heidrich, an acquaintance of Ward's who had been working independently on computational aspects of HDR, was also introduced to the project.

“Lorne, Helge, and Greg had early stage hardware when we were introduced and were looking for contributors on the software side, which is where my group and I came in,” said Dr. Heidrich. “Within a few months, we developed improved algorithms and calibration methods for a broad range of images, and they were compatible with real-time calculation on GPUs.”  (Dr. Heidrich also served as a co-supervisor, with Dr. Whitehead, of Helge Seetzen’s PhD studies on HDR technology.)

Key to the success of the HDR design was its enhancement of both the brightness of colours and darkness of shadows. This gave the picture a wider band of colours and contrasts. In comparison with the 300:1 range for standard screens at the time, the HDR prototype reached a vastly superior 50,000:1, coming much closer to the luminance range encountered in the real world. 

A prototype display was showcased at the Association for Computing Machinery (ACM) Special Interest Group Graphics (SIGGRAPH) 2003 conference in San Diego as one of 21 promising new technologies selected by conference organizers. The following year, the team published its groundbreaking 2004 SIGGRAPH paper describing the first authentic HDR display.

UBC spin-off first to introduce HDR display commercially

The business leadership of Brightside Technologies, including CTO Seetzen, was quick to develop the prototype technology into the first commercial HDR display. Makings its first entry into the world of image processing, U.S.-based Dolby Laboratories Inc. acquired Brightside in 2007 and transformed it into Dolby Canada, a research facility in Vancouver. As the HDR tech lead for Dolby, Dr. Seetzen went on to launch Dolby's first video products, having established HDR as a solid solution in the display industry.

In 2008, Dolby pledged $1.15 million in funding to continue research in HDR imaging technologies at UBC. The funds established UBC’s Dolby Research Chair in Computer Science for Dr. Heidrich’s research including psychophysical and perceptual studies of HDR and related technologies. The funding also supported UBC electrical and computer engineer / GRAND researcher Dr. Panos Nasiopoulos's investigations of devices capable of capturing, compressing and delivering HDR images.

Dr. Heidrich's research led to several new applications – displays, content authoring tools, and software for converting legacy standard-contrast video to HDR. It also led to fundamental research into how humans perceive extreme contrast and colour. The work has challenged some of the assumptions held by the imaging science community because of limitations in traditional display technology.

The next stage in Dr. Heidrich’s career will be as the Director of the KAUST (King Abdullah University of Science and Technology) Visual Computing Center in Thuwal, Saudi Arabia, starting in 2014. While on leave from UBC, Dr. Heidrich will continue his HDR research and collaborations with colleagues in the GRAND network and the Imager Computer Graphics Laboratory at UBC’s Department of Computer Science.

“We look forward to Wolfgang’s ongoing participation in our network,” said GRAND’s scientific director Dr. Kellogg Booth, “and to the additional international collaborations that he will be developing as part of his new role at KAUST.”

As for the future of HDR, advances in computational displays and cameras are likely to continue to be a hotbed for innovation and to make a major impact on digital media devices – from cell phones to digital cinema – in the coming years.

“HDR displays are a great example of the importance of basic research and the need for strong, multidisciplinary teams to tackle fundamental problems in digital media,” Dr. Booth commented. “It is also a reminder that innovation often comes only after a series of incremental steps and that strong ties with industry partners are necessary to fully realize the potential of new ideas.”

Dolby is a registered trademark of Dolby Laboratories.

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