Thursday, June 12, 2008

3-D Viewing without Goofy Glasses

Philips's new displays bring high-quality, 3-D images a step closer to your living room.

By John Borland

With the release of a new set of 3-D video screens next week, Philips Electronics is bringing a sci-fi cinema standby a little closer to everyday use. Philips' WOWvx displays--which allow viewers to perceive high-quality 3-D images without the need for special glasses--are now beginning to appear in shopping malls, movie-theater lobbies, and theme parks worldwide.

The technology uses image-processing software, plus display hardware that includes sheets of tiny lenses atop LCD screens. The lenses project slightly different images to viewers' left and right eyes, which the brain translates into a perception of depth. For now, the screens are expensive and not yet marketed for home use. But Philips, which first released the technology in 2006, is working on technical improvements that will make the screens better suited for the home.

"We think this is a huge leap," says Wolf-Nils Malchow, production manager for the Munich-based Kuk Filmprodukion, an early producer of content for the displays and of promotional films for clients such as Deutsche Telekom. "It is a bit like a few years ago, when [high-definition video] kicked in. Everyone is excited about it."

Small-screen 3-D: This is an artistic rendering of WOWvx 3-D screens, which are coated with lenses that project slightly differing images, allowing viewers to perceive depth without wearing 3-D glasses.
Credit: Courtesy of Philips

A planned deployment of about 50 screens in U.S. theater lobbies has begun at the Bridge Theater in Los Angeles. South African shopping malls have ordered about 350 of the screens. Other rollouts include malls and coffee shops in Russia, European casinos, and theme parks, the company says. And at next week's Infocomm trade fair in Las Vegas, new 52-inch and 22-inch options will be added to the existing 42-inch model.

This isn't the first time that 3-D has made a splash. The early 1950s and early 1980s each saw their own fads. The 3D movies from the 1950s were filmed with two cameras, with the separate images then projected simultaneously. The familiar red-and-blue-lensed glasses were used to trick the eyes into interpreting color differences as distance. Modern 3-D movies employ more-sophisticated approaches, such as projecting the separate images in polarized light and using glasses with polarized lenses that filter out one image on each side.

But a combination of advances in computer image processing and industrial optics has allowed companies like Philips to develop their glasses-free technique.

As with earlier techniques, the illusion requires specially-created content to start with. In this case, a digital movie file effectively has two frames for each ordinary movie frame. The first is an ordinary color image, identical to what would be seen on a two-dimensional screen. A second frame, rather than showing a second offset view, encodes information about how viewers should perceive depth in the first frame. It appears as a grayscale version of the first, with white indicating foreground objects, black denoting deep background, and shades of gray indicating points in between.

Capturing 3-D: Philips's WOWvx screens require specially created videos that record two frames for each scene. The first frame contains ordinary color information. The second frame contains depth information for each pixel, with white denoting foreground and black indicating deep background. Software and hardware built into the screens then use this information to create differing versions of images as the video plays and send them to the display. In a final step, lenses atop the screen project these slightly-differing images so that the left and right eyes see different versions, creating the illusion of depth.
Credit: Courtesy of Philips

Then, special PC-based hardware and software--housed in the display itself--processes the pair of images as the video is played. The information in the second frame is used to transform the original color frame into nine separate images, each slightly offset from the last, as though the camera had been moved a few inches to the side each time. All nine are then sent to the screen.

To allow viewers to perceive these images, the LCD screens are overlaid with three-pixel-wide cylindrical lenses that direct the different images into side-by-side paths. A nearby viewer will see one of these images with each eye--the first and third, or third and fifth, for example--thus producing the illusion of image depth.

The multiple images allow viewers to walk around the viewing area--a cone about 20 degrees wide--without disturbing the 3-D illusion, says Philips product manager Erik van der Tol. This cone is duplicated several times on each screen, further widening the 3-D viewing area.

The number of content producers working with the format is small, but growing. Kuk creates live-action stereoscopic films, using two cameras to film. Others, such as the London-based SquareZero, work primarily with computer graphics, which requires a less specialized production process.

"You do get really good depth perception," says SquareZero head of animation Olly Tyler. "The image seems to go into the screen and come out of it."

As with any new technology, there are glitches. With the company's 42-inch screens, the 3-D effect works most effectively only up to a distance of about 12 feet, and if you view the screen at the boundary between the three "cones," you experience garbled images. In addition, the quality of ordinary two-dimensional images on the screens is diminished. Finally, a 42-inch screen will set you back $12,000 (prices on the new 52-inch and 22-inch models being released next week have not yet been specified).

Still, while today the company is focusing squarely on the advertising and display market, it does have its eye on the consumer market. Researchers are working on expanding and smoothing the viewing area and on improving the two-dimensional viewing quality in order to make the screens entirely backward-compatible with ordinary video.

"Look a couple of years ahead, and I think this will be an acceptable technology for the home," says van der Tol. "The Hollywood scene is definitely interested." Philips is not alone; Sharp Electronics, along with a handful of small companies such as Dimension Technologies and Alioscopy, offer competing products.