3D without glasses comes to high-definition displays

Human 3D experience
When a person views media such as photographs and television in 2D, each eye gathers essentially the same information. In other words, because the image has no real depth, there is only one way of viewing it. If there is any 3D impression at all, it comes from visual clues in the image, such as perspective.

The goal of 3D displays, then, is to get a distinct image into each eye of the viewer. From that point, the viewer's brain takes over, processing each image in the same, natural way in which it processes the images it receives from the three-dimensional world.

A characteristic common to all 3D displays is the creation and display of more than one view of a scene. Formerly, viewers had to wear special glasses to discern the views. In the last few years, a number of companies, among them Philips 3D Solutions, have introduced autostereoscopic 3D displays - displays that do not require users to wear special 3D glasses.

Two different images are combined by the brain into a 3D visual experience
3D is based on the way the human brain and eyes wor k. Because the pupi ls of a p erson's eye are about 6.5 cm apar t , each eye views a scene from a differ ent angle a nd gener ates a unique image . The brain merges the images to create a single picture. The slight difference between the image from t he right eye and the image from the lef t eye allows the brain to judge the depth. Stereoscopic vision is attained.

Multiview lenticular lens technology
A sheet of lenticules, which are transparent, cylindrical lenses, is fixed on a liquid-crystal display. The transparency of the lenticular sheet is crucial because it allows for full brightness and contrast. Other methods, such as the parallax barrier, rely on the blocking of light and therefore greatly reduce brightness. The lenticular sheet is fixed on an active matrix display, like LCD in such a way that the image plane of the LCD is at the focal plane of the lenses. Because of this, a person's eye observing the screen perpendicular to the display sees the portion of the LCD that is directly under each lens. The other eye, observing the screen from a different angle, sees a portion of the LCD that is off-center under each lens.

Since the LCD under each lens is divided into subpixels, each eye sees different subpixels. To create the 3D effect, all that remains is to put the correct information on the various subpixels. Multiple views are achieved by placing the lenticular sheet over the LCD in such a way that each lens overlaps several subpixels, sending the light of each subpixel in a different direction. By repeating the lenses, entire views can be sent in different directions.

Slanted lenticular technology
A characteristic of all 3D displays is the tradeoff between pixel resolution and depth. In a scene viewed in 3D, pixels that in 2D would have contributed to high resolution are used instead to show depth. If the lenticular sheet were placed vertically atop the LCD, then horizontal resolution would drop by a factor equal to the number of views. (A nine-view vertical lenticular display, for example, would cause a nine-fold decrease in horizontal resolution and an unbalanced, elongated pixel shape.)

A sheet of slanted lenticules, by contrast, distributes the resolution loss in the vertical and horizontal planes. (A nine-view slanted lenticular sheet, for example, causes only a threefold decrease in both vertical and horizontal resolution and, moreover, maintains a more balanced pixel shape.) The result is a clearer, more lifelike image. The slanting allows for the interspersing of odd and even views. Interspersing is necessary because of the gaps between each pixel on the LCD. Without interspersing, the gaps between the pixels would be magnified along with the images. Because of interspersing, observers perceive a viewing zone without gaps.