Signal Processing for Stereoscopic and Multi-View 3D Displays - Signal Processing Systems - page 14

a b c

Fig. 8 Multiview displays: ( a ) lenticular sheet, ( b ) parallax barrier and ( c ) visibility zones of the

views

and appear close to each other, the triplet is perceived as one full-color pixel. Such
pixel is a building block of the view seen from that direction.
As a result of applying the optical filter, for every sub-pixel there is a certain
angle from which it is perceived with maximal brightness; that angle we call the
optimal observation angle for the sub-pixel. The vector, which starts from the sub-
pixel and follows the optimal observation angle, is the optimal observation vector
for the sub-pixel. The optimal observation vectors for all sub-pixels of the same
view are designed to intersect in a tight spot in front of the multiview display.
From this spot the view will be perceived with its maximal brightness. That spot is
referred to as being the optimal observation spot of the view. Outside of the optimal
observation spot there is a range of observation angles from which a given view is
still visible, but with diminished brightness. That range is called the visibility zone
of a view. For most multiview displays visibility zones of the views are ordered in
the horizontal direction. A notable exception is the SynthaGram display produced
by StereoGraphics [ 40 ] which has nine views with visibility zones ordered in a 3-
by-3 grid. As the amount of the pixels provided by the underlying TFT is limited,
there is a trade-off between the number of views created by a 3D display and
the resolution of each view. As stereoscopic depth cues are perceived mostly in
horizontal direction, most multiview display designs do not allocate pixels for extra
views in the vertical direction [ 28 , 36 , 38 , 41 ] .
When horizontally ordered, the visibility zones appear in a fan-shaped configura-
tion as depicted in Fig. 8 c . The repetitive structure of the optical filter creates several
observation zones for any view; these follow the fan-shaped configuration as well.
After the visibility zone of the last view, the first view becomes visible again. This
creates one central set of visibility zones directly in front of the screen and a number
of identical sets to the side as shown in Fig. 8 c . The zones marked as “1” and “1R”
are observation zones of the same view.