How Does 3D TV Work?
Since our two eyes are located at different positions in the head, the images perceived with the left eye are slightly different from those observed with the right eye. Differences in the horizontal positioning of objects in the left and right eye images are known as disparities, and our brains are smart enough to convert this into depth information-much like a surveyor solving a triangulation problem. 3D-TV mimics this real-world situation by presenting the viewer with two sets of slightly different images, one for the left eye and one for the right eye. Thus, compared to standard TV, 3D-TV conveys extra information in the form of disparity information contained in the dissimilar images, thereby greatly enhancing the sensation of depth and presence.
The major difference between a standard TV and a 3D-TV is the enhanced technologies that are needed to separately display images to the left and right eyes of a viewer. In the past, successful implementations of 3D display systems have involved some form of special glasses, such as red-blue or red-green colored glasses with anaglyphs, polarized glasses with the polarization method, and liquid crystal shutter glasses with time-sequential technology. The need to wear glasses, however, is possibly the most restrictive barrier preventing broadcasters from considering 3D-TV as a serious option. Today, with the advent of autostereoscopic displays, this gloomy scenario may change, as with these displays the viewer is not required to wear any special glasses to experience the 3D effect.
Autostereoscopic displays are conventional displays – with a twist. The most common are equipped with a plastic lenticular sheet made of many tiny lenses placed in front of the LCD screen. The tiny lenses redirect the light coming from each pixel in a controlled fashion, so that each eye sees different views. Most autostereoscopic displays typically employ nine to 16 different views of a scene, whereas a regular TV displays only one. These different views are presented simultaneously on the TV screen but they are spatially interleaved in alternate columns of pixels. The lenticular sheet redirects the light coming from each view in a specific direction in a fan-like fashion. As a result, one eye sees one view whereas the other eye sees another view, recreating the stereoscopic effect.
