Hybrid 3D display shows 2D images clearly

A prototype display has been developed that allows viewers with stereo glasses to watch in 3D while others without the specs enjoy clear quality 2D images.
The developments made by researchers at the University of California in Santa Cruz could lead to hybrid displays being produced as well as boosting the market for 3D enabled screens by making the technology more versatile. Students involved in the project are already looking to set up a company based on the technology.

“There are a lot of reasons why it would be desirable to not need the glasses,” said project leader James Davis, associate professor of computer science at the Baskin School of Engineering in UCSC.
“They can be expensive, so you wouldn't want to buy extra pairs, and they can interfere with other activities.”

With current 3D screens showing a different image to each eye through the stereo glasses, a viewer without the glasses sees both images superimposed, resulting in blurriness or ghosting.

Davis’s hybrid display shows separate left and right images when viewed through glasses, but those without glasses see only the left image. The system also displays a third image, which is not seen through either lens of the glasses. The third image is the negative of the right image - bright where the right is dark, and dark where the right image is bright - canceling out the right image so those without glasses see only the left image.

With this simple version of the system, 2D viewers see a low-contrast image, because the darkest pixel is relatively bright. To restore acceptable contrast to 2D viewers, the researchers allowed the images seen by the left and right eyes of 3D viewers to have unequal brightness, where the left becomes brighter and the right dimmer. Then they conducted several experiments to determine the optimal brightness ratio between right and left images. They found that brightness ratios in the range between 20 percent and 60 percent were acceptable for viewers both with and without glasses.

The researchers built a prototype of their 3D+2D TV by aligning a 3D projector with a second, polarised projector used to project the negative of the right image. The image from the polarised projector is not visible through the LCD active shutter glasses synchronised to the 3D projector.

Davis and his team will present their 3D+2D TV technology at Siggraph 2013, the 40th International Conference and Exhibition on Computer Graphics and Interactive Techniques on July 25 in Anaheim, USA.