(Image courtesy: good3dtv.com)

Everybody likes 3D—be it in signage, movies, television or games—but nobody likes those gauche glasses, despite sincere efforts by manufacturers to make them fashionable and creative. Apparently, Look3D, along with Warner Bros and RealD, has designed special, Middle-Earth inspired, collectible glasses with a folding arm frame and hammer-forged steel look for Peter Jackson’s 3D movie The Hobbit. Despite all the excitement and hype around 3D movies like Avatar, many refrain from watching these due to the sheer irritation of wearing 3D glasses.

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Understandably, several R&D labs are researching various glasses-free alternatives for 3D viewing. At the Consumer Electronics Show (CES)earlier this year, Toshiba and Nintendo grabbed the viewers’ attention with auto-stereoscopic 3D technologies—making some trend-watchers wonder whether 2012 would be the year of 3D without glasses. Unfortunately, it has not unfurled that way.

Will Greenwald, a consumer electronics trend-watcher, writes in one of his columns: “There hasn’t been much word on the glasses-free 3D HDTVs since CES, and there’s a reason for that: glasses-free 3D isn’t happening any time soon. 3D glasses can offer a solid 3D picture across a wide viewing angle depending on the HDTV and 3D technology used (passive 3D glasses tend to display more crosstalk when watched from the sides). Glass-free 3D requires users to keep their heads in the sweet spot where the two images align to their respective eyes… We might see a lot of promise in what the technology could be given time and resources, but for now it simply is unworkable for most users.”

Toshiba has not spoken about the glasses-free HDTVs since the demo at CES. Nintendo 3DS, despite its merits, has not caught on at any feverish pace. Other companies like Sony claim that they are focusing on glasses-free 3D only in small-screen gadgets like handycams as of now. In fact, many major 3D players in India avoided speaking about glasses-free 3D when approached, saying it is still slotted as future-tech and nowhere near widespread implementation yet.

Nonetheless, the quest for 3D without glasses continues, and one day the researchers will hit the bull’s-eye. If not on the product front, 2012 appears to have been a notable year for glasses-free 3D in terms of R&D. Here we take a quick look at six interesting auto-stereoscopic alternatives that have been announced in the recent past.

1. Nintendo 3DS – Are you game for 3D?
Nintendo 3DS is an auto-stereoscopic 3D version of the popular gaming device that operates without glasses. It employs the parallax barrier technique (refer the box on next page). The handheld gaming device has two screens—one on top and the other on bottom—both containing multiple LCD layers. The bottom screen shows only dark and light bands, while the top screen shows two offset images representing the perspectives of both eyes. The light is blocked from the top screen using the dark bands on the bot-tom screen so that the users see the images for each eye at the right time.


Nintendo 3DS

The user can vary the intensity of 3D using a slider, or toggle between 2D and 3D modes as desired. Overall, the 3D performance is decent. However, the 3DS, like most parallax barrier based devices, requires the user to be seated at a sweet spot in front of the screen. Viewing from an angle can be unnerving. Understandably, many gamers have admitted on their blogs and reviews that they prefer to play games with 3D switched off, as sitting stock still while playing games defeats the purpose of it all!


Traditional Glassy 3D

Commonly, 3D products are based on techniques of stereoscopy, inspired by the working of our eye. Our eyes are like two lenses, each capturing the same image from different angles. The brain processes and merges the two images, creating a 3D image for us. Similarly, 3D systems rely on telecasting slightly different images to each eye, and letting the brain combine these into a 3D image. Shutter glasses or polarised glasses may be used to achieve this.

Shutter glasses use lenses which are actually small liquid-crystal display (LCD) screens, and alternately shut off the right and the left eye. The television, in turn, alternately telecasts images meant for the left and right eye (stored in the even and odd fields respectively of its video signal). The brain processes these into a 3D image for the viewer. However, this effectively reduces the television’s refresh time by half, and could cause headache in some viewers. Brands such as Panasonic, LG and NVIDIA use this technology.

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Some movie houses like IMAX use polarised glasses. Here, the two lenses of the glass are polarised differently, thereby showing different images to each eye. However, in this case, the movie has to be shot using two cameras, or a single camera with two lenses. Correspondingly, two projectors fitted with polarising filters on their lenses are required to show the movie. When viewed through the polarised glasses, the left eye sees only those images which the left projector is screening, while the viewer’s right eye sees only those images which the right projector is screening. As both the images are taken from different angles, the viewer’s brain combines the two to come up with a single 3D image.

2. Toshiba’s ‘Naked Eye’ 3D TV – Playing hide- and-seek
Last year Toshiba unveiled a 140cm (55-inch) glasses-free 3D TV, model Regza 55X3. The TV employs integral imaging—a technique that uses a two-dimensional array of many small lenses or holes to create 3D effects. According to the company, the integral imaging technology applied to this model uses lenticular lenslets to generate nine parallax images in 3D mode, which create multiple wide-angle viewing zones in front of the television. The model runs on Toshiba’s Cevo-Engine.

The television includes face tracking technology to automatically make adjustments and ensure optimal experience at suitable 3D viewing positions. Apparently, up to nine users can comfortably enjoy glasses-free 3D. However, reviews suggest that moving from the sweet spot can cause the 3D effects to collapse.

Users can easily switch between 2D and 3D. In 2D mode, they can enjoy a resolution four times that of a normal full high-definition (HD) television, making the 55X3 the world’s first quad full HD model. Despite its grand entrance, the model is still available only sparsely and at a scary price point of above $7000!


Glasses-free auto-stereoscopic options

Auto-stereoscopic 3D technology does not require any special glasses. There are two well-known ways to achieve this, and there are several prototype and demo models based on these—not to forget a few commercial ones as well. However, it is not yet in the mainstream and most companies are still working on making this technology practicable.

Lenticular. The first technique involves the use of special LCD screens, the display surface of which is pasted with an array of tiny cylindrical plastic lenses called lenticules. These lenticules magnify the image shown to the viewer, and provide an effect similar to what you get when you view a cylindrical image—that is, your left eye and right eye would see two different 2D images. The brain combines these to form one 3D image. However, lenticular lenses are dependent on where you sit, and even budging a little from the sweet spot would result in distorted images. A television would generally have more than one such spot, so that multiple people can view the show.

Parallax barrier. Companies like Sharp, LG and Nintendo are, however, pursuing the parallax barrier method, as it is more viewer-friendly, and allows for both 3D and regular 2D viewing. Devices that use this method have a fine layer of liquid crystals placed in front of the screen. This layer, known as the parallax barrier, has slits in appropriate positions to enable the transmission of alternating images to each eye of the viewer when a slight voltage is applied to it. These images are slightly different from each other, and can be combined by the brain to form a 3D image. However, this method also requires the viewers to sit at preferred spots. This parallax barrier can be easily switched on or off using the television’s controls, thereby enabling the TV to juggle between 3D and 2D viewing.

3. Korean Research: 3D using ‘Venetian Blinds’ on screen

A team of researchers led by Byoungho Lee, professor at the School of Electrical Engineering, Seoul National University, has developed a new technology for watching 3D movies in theatres without wearing clumsy goggles. Apparently, this technology will also be much cheaper than options like parallax barrier and even the goggle-based technology currently being used in theatres. According to press reports, the researchers wish to take 3D viewing to the next level with a method that, if validated by further research, might constitute a simple, compact and cost-effective approach to producing widely-available 3D cinema, while also eliminating the need for wearing polarising glasses.

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In layman terms, the team is trying to produce a 3D effect by using something like Venetian blinds—because the slats in such blinds generally create a 3D effect by limiting the image that each eye sees.

The team’s setup uses a single front projector against the screen. Polarisers are attached in strips to the screen to stop the passage of light after it reflects off the screen, giving a Venetian Blinds slat effect. To block the necessary portion of light, the researchers have added a specialised coating known as a quarter-wave retarding film to the screen. This film changes the polarisation state of light so it can no longer pass through the polarisers. As the light passes back either through or between the polarising slates, the offset effect is created, producing the depth cues that give a convincing 3D effect to the viewer, without the need for glasses.

The technology is being tried in-house by the team, in small screens. It might take a few years for it to be fine-tuned sufficiently for commercial use. Going forward, the team hopes to refine the method and apply it to developing other single-projector, frontal methods of 3D display, using technologies such as passive polarisation-activated lens arrays and the lenticular lens approach.

4. 3D Analyser: Making 3D content creation easier
3D television is catching on here and there in the world, but not as fast as manufacturers would like. One reason is the lack of good-quality content. This shortage is often attributed to the cost and time involved in creating 3D content—especially the post-production processes. A new technology has been devised that makes it possible to generate 3D content in real time—that too for viewing without glasses.


Polarisers are attached in strips to the screen, which gives a Venetian blinds’ ‘slat’ effect to create 3D (Image courtesy: www.dailymail.co.uk)


Multi-camera content creation (Image courtesy: hhi.fraunhofer.de)

The cost, weight, power consumption and bandwidth requirements of auto-stereoscopic videos are too much. To create high-quality auto-stereoscop-ic content, numerous camera angles of each shot are needed. However, it is costly and impracticable to place 10-20 cameras on a set. This led to the 3D Analyser project at the Fraunhofer Heinrich Hertz Institute.

In the past, the team had developed a stereoscopic analyser called STAN that corrects standard 3D images in real time to make live broadcasts possible. The new tool builds upon STAN to generate up to 25 views of the same scene from slightly different viewpoints—thereby making glasses-free 3D possible. The tool works well when tested offline in the lab, but a lot of work needs to go into making it suitable for real-time broadcasting.

5. MIT’s Tensor Display – More life to 3D
The actual 3D view that we get of life around us is very different from what we see on 3D screens today. When we move, our perspective of an object changes in real time. However, when we move in front of a 3D screen, we see only a distortion! To create a realistic image without distortions would require hundreds of perspectives and screens with fantastic refresh rates—a challenge that continues to daunt the 3D industry.

That said, the Massachusetts Institute of Technology, Boston, has recently developed a wide field-of-view LCD technology that can, they claim, display 3D in a more life-like way than other standard 3D displays, without the need for glasses. Called a Tensor Display, it comprises stacks of light-attenuating layers, such as multi-layer LCDs. Rapid temporal modulation of the layers is exploited, in concert with directional back-lighting, to allow large separations between viewers. Tensor displays support smooth motion parallax and binocular disparity at a high resolution for a large depth of field over a wide range of viewpoints.

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To help you understand the technology better, let me draw a parallel with the double-screened Nintendo 3DS, which is also made up of multiple LCD layers. However, the Tensor Display consists of three screens, rather than the two used in the gaming device, since MIT’s technology is meant for larger screens. To make a TV or a larger display that presents highly realistic 3D images would require hundreds of perspectives and a refresh rate of over 1000 Hz, if only two screens are used. Using a third display pulls down the refresh rate requirement to 360 Hz because it displays yet another pattern, which has a whole new set of algorithms to help cut the amount of information sent to LCD screens.


MIT’s Tensor Display uses multi-layer LCDs and directional backlighting to present realistic 3D views without glasses

6. Ultra-D: Setting new standards for 3D quality
An Indian-led company called Stream TV Networks in Philadephia is creating waves in countries like Germany, China, UK and France, with its new glasses-free 3D technology called Ultra-D. Mathu Rajan, CEO of Stream TV Networks, summed it up neatly in a recent press report: “Ultra-D is the first 3D-without-glasses solution that has been able to eliminate viewing angles and offer the high-quality, glasses-free 3D experience we all have been waiting for. We have received positive feedback that Ultra-D is the only 3D-without-glasses solution developed that is ready for the consumer market.”

Ultra-D has been demoed at various expos and seems to have received a warm welcome by the market. Recently, Stream TV Networks announced a technology partnership with Hisense to create a line of televisions and other products featuring its Ultra-D technology. To begin with, they will be launching a 107cm (42-inch) 1080p auto-stereoscopic 3D display.

You would have realised by now that most of the parallax barrier based displays require the user to sit still in a sweet spot to get the desired effect. While this is okay for smart phones and even gaming devices to some extent, it is a huge drawback in devices like TVs. Ultra-D uses a different technology to overcome this problem. It uses a microlens that covers the standard display and, with the aid of their proprietary software and firmware, shows viewers up to nine images—each with a slightly different angle on the scene. This way each eye will see four images, for example, and as you move around to different viewing angles, you see a slightly different image that retains the 3D effect. The best part is that the technology package includes an auto-converter box called SeeCube that can seamlessly convert 2D and 3D stereoscopic media into a glasses-free 3D format in real time.


Ultra-D screen

Ultra-D technology can be used with PCs, digital photo frames, tablets, TVs, set-top boxes and so on—not to forget its applications in non-commercial spaces like military, medicine, research and therapy. It also supports numerous video feed formats including cable and satellite TV channels, Blu-ray, XBOX, PS3, and media websites such as Netflix, Hulu and YouTube. It can also convert content from iPad, iTunes, Appstore and Apple TV. So users can plug any source into the box and watch glasses-free 3D content on their Ultra-D displays. Reviewers say that Ultra-D’s resolution is not as high as other 3D TVs’, but this problem can be overcome with a bit of fine-tuning.

In short, there is a lot of activity on the auto-stereoscopic 3D front. Companies like Tridelity AG have glasses-free displays that can be used for signage, etc. Industry leaders like LG, Samsung, Sony and Philips have prototypes and niche models. Sony, for instance, is known to have filed a patent application related to this in May this year. The patent pertains to an auto-stereoscopic display that adjusts the separation of the two images (for both eyes) automatically according to a viewer’s distance from the screen, to ensure optimal viewing from many several positions and viewing angles. While no such product has been announced by the company yet, this goes to show that almost all industry majors have their eyes on glassless-3D. While it might take months or even years, surely viewers will prefer to watch 3D without glasses once the wrinkles in the technology are ironed out.