Blu-ray 3D without the goggles

Scientists at the Heinrich Hertz Institute (HHI) in Berlin have developed a system to make Blu-ray 3D movies compatible with a new generation of glasses-free, autostereoscopic television sets.

In order for the future to become 3D, it will probably have to become glasses-free. Whilst 3D television sets have been on the market for some years now, many believe that the need for viewers to wear specialised eyewear to see the stereoscopic displays, has inhibited sales. In light of this, television manufacturers are keen for autostereoscopic devices – 3D displays that require no eyewear – to reach store shelves as soon as possible.

Blu-ray Discs containing 3D movies show two images – one for the left eye and one for the right. This technology is ideal for the current crop of 3D televisions as specialised eyewear is used to make the 3D images viewable. However, a new generation of autostereoscopic television sets is due to hit the market within the next couple of years. In order to negate the need for 3D glasses, these systems emit anything upwards of five images simultaneously. As a result, traditional 3D content on Blu-ray Discs is incompatible with the new devices.

In order to avoid a dearth of material suitable for use with this new generation of 3D televisions, a team of German-based researchers has developed a system to translate Blu-ray movies into content that is compatible with autostereoscopic displays. Christian Riechert and his colleagues at the HHI’s Fraunhofer Institute for Telecommunications were able to overcome incompatibility issues by developing a system capable of automatically generating ‘depth maps’. I spoke to Riechert to find out more about the system that he has helped to develop. I began by asking him to outline the problem that he and his colleagues were trying to overcome.

"Standard 3D displays – the kind that are currently on the market – emit one image for each eye," he explained. "In order for their 3D images to be intelligible, specialised glasses must be worn by the viewer. These glasses separate the image intended for the left eye from that intended for the right. The glasses allow each eye to see a different image and thus help to create the 3D effect.

"A new generation of autostereoscopic displays will negate the need for viewers to wear glasses by emitting greater numbers of images simultaneously. By placing filters in front of these displays, manufacturers are able to send light from different pixels in separate directions. This means that viewers will actually see different images from different positions around the screen."

One potential problem with autostereoscopic technology is a lack of compatible content. The need to emit more than two images at once means that traditional 3D material, such as that contained on Blu-ray Discs, will be inadequate. Through the use of depth maps, however, Riechert and his team have managed to overcome this problem.

"Our system is quite simple," he explained. "Imagine that you have a camera capturing an arbitrary scene. A person might be standing in front of a background, for example. The depth map assigns a distance from the camera for each pixel. The person is standing in front of the background so the pixels comprising the person have values lower than those comprising the background. Our system is able to estimate these distances, and in doing so, generates a sufficient number of images for an autostereoscopic display. The system only requires two images, and from these, it can produce a depth map."

At present, autostereoscopic displays – which haven’t even reached the market yet – use between five and 10 images to produce 3D pictures. However, it is thought that as the technology advances, the number of images emitted by these displays will increase. I asked Riechert whether the system that he has developed will be able to keep pace with the advancement of 3D displays.

"Actually, it will," he replied. "This is one of the big advantages of our system. It can calculate any number of differences within a certain range, and so it can handle any number of images. At our laboratory, we use a variety of screens that emit different numbers of images. Our system works with all of these screens."

Riechert and his colleagues plan to present their system at the IFA trade show in Berlin between 31^st August and 5^th September 2012. I asked him when he thought that this technology might reach the market.

"I think that it will take at least one year – maybe two – but it should be fairly soon," he replied. "At present, numerous manufacturers are interested in autostereoscopic devices because whilst 3D is interesting to many people, the glasses are off-putting. Manufacturers are therefore really trying to push glasses-free technology to the market. I would guess that we will see these televisions in stores within the next couple of years."

If events transpire as Riechert predicts, his system could be ready for use within a similar timeframe as the glasses-free displays themselves. I concluded our interview by asking whether or not the system is likely to need updating as autostereoscopic devices improve.

"There is always room for improvement," explained Riechert. "I have already mentioned that our system will be able to deal with increased numbers of images, but what might not be so straightforward are the enhanced resolutions. In order to allow displays to emit more images, their resolutions will need to be increased. As the number of images displayed increases, the resolution of each individual image is reduced. Autostereoscopic displays will therefore profit from higher base resolutions. One must remember that this technology is still in its infancy. Currently, these displays have fairly low resolutions – perhaps standard definition (SD) resolutions for each image. In the future, however, televisions will probably be capable of producing each image in high definition (HD). We are therefore conducting ongoing research to gauge how well our algorithm is able to cope with higher quality images."