Auto 3-D, more formally known as autostereoscopic imaging, is a display technology that enables a 3-D (three dimensional) effect without requiring the viewer to wear special glasses. Stereoscopy is defined as any technology that enables an illusion of depth in a display. Traditional 3-D TV (and movies as well) typically enable that effect by presenting two separate images - one for the right eye and one for the left - that are incorporated through the use of 3-D glasses. In an auto 3-D display, screen-based technologies allow a viewer sitting within a specified range to perceive depth in the display through the naked eye. There are two classes of autostereoscopic displays. One type tracks the viewer's head position to ensure that each eye is presented with a different view. The other type of display uses multiple perspectives of each frame presented simultaneously so that, within a given range, a viewer will See: Separate Perspectives With Each Eye