Multi-View Autostereoscopic Visualization using Bandwidth-Limited Channels

Multi-View Autostereoscopic Visualization using Bandwidth-Limited Channels

Svitlana Zinger (Eindhoven University of Technology, The Netherlands), Yannick Morvan (Philips Healthcare, The Netherlands), Daniel Ruijters (Philips Healthcare, The Netherlands), Luat Do (Eindhoven University of Technology, The Netherlands) and Peter H. N. de With (Eindhoven University of Technology, The Netherlands & Cyclomedia Technology B.V., The Netherlands)
Copyright: © 2012 |Pages: 16
DOI: 10.4018/978-1-61350-326-3.ch019

Abstract

The increasing popularity of stereoscopic cinema and television paves the way for more advanced stereoscopic technologies, such as high-resolution multi-view autostereoscopic displays. The amount of information conveyed by such displays surpasses, however, the bandwidth capacity of the current broadcasting infrastructure. In this chapter, we will focus on technical solutions to overcome the bandwidth bottleneck that only minimally affect the viewer experience. The presented solutions consist of (1) employing depth-based free-viewpoint interpolation with the aim to reduce the number of views that need to be transmitted, (2) the optimal compression of the depth and texture images while minimizing the resulting image artifacts, and (3) the optimal resolution considerations for a given autostereoscopic display.
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Background

Multi-view autostereoscopic displays and the problem of video signal transmission for such displays are discussed in this section. We introduce the concept of stereoscopic viewing and discuss the broadcasting options for it.

Multi-view Autostereoscopic Displays

A stereoscopic display presents the viewer with different images for the left and the right eye. Provided that these images contain proper stereoscopic information, the viewer will have the sensation of seeing depth. Principally there are two kinds of stereoscopic displays: the first type requires the viewer to wear goggles or glasses, and the second type, called autostereoscopic display, allows stereoscopic viewing without any external aid. The autostereoscopic effect can be achieved by using lenticular lenses (see Figure 1), or parallax barriers in order to emit different images when viewing under a (slightly) different angle. Modern so-called multi-view autostereoscopic displays provide between 8 and 25 views in order to achieve a smooth transition when the viewer moves his head (van Berkel, 1999; Dodgson, 1997; Maupu et al., 2005; Ruijters, 2009).

Figure 1.

The autostereoscopic lenticular screen. The various subpixels are refracted to different angles by the sheet with the lenticular cylindrical lenses. In this way the left and the right eye are presented with different views.

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Multi-view autostereoscopic displays can be regarded as three-dimensional light field displays (Levoy & Hanrahan, 1996; Isaksen et al., 2000) (or four- dimensional, when also considering time). The dimensions are described by the parameters (x, y, φ), whereby x and y indicate a position on the screen and φ indicates the angle in the horizontal plane in which the light is emitted. The light is further characterized by its intensity and its color.

The multi-view lenticular display device consists of a sheet of cylindrical lenses (lenticulars) placed on top of an LCD in such a way that the LCD image plane is located at the focal plane of the lenses (van Berkel, 1999). The effect of this arrangement is that LCD pixels located at different positions underneath the lenticulars fill the lenses when viewed from different directions; see Figure 1. Provided that these pixels are loaded with suitable stereo information, a 3D stereo effect is obtained, in which the left and right eyes see different, but matching information.

The fact that the different LCD pixels are assigned to different views (spatial multiplex) leads to a lower resolution per view than the resolution of the LCD grid (Dodgson, 1997). In order to distribute this reduction of resolution over the horizontal and vertical axes, the lenticular cylindrical lenses are not placed vertically and parallel to the LCD column, but slanted at a small angle (van Berkel et al., 1996). The resulting assignment of a set of LCD pixels is specified by the display manufacturer. Note that the red, green, and blue color channels of a single pixel are depicted in different views.

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