Image Processing Reference
In-Depth Information
5.2.2
3D Holoscopic Imaging Display
For displaying 3D holoscopic content, a similar optical setup can be used, where a
simple flat panel display is used to project the recorded 3D holoscopic image
through the micro-lens array, as illustrated in Fig.
5.1b
. Then, the intersection of
the light beams passing through the micro-lenses recreates a full 3D optical model
of the captured object, which is observable without the need for special glasses.
3D holoscopic imaging is one of the promising autostereoscopic techniques for
improving the quality of experience in 3D visualization. Due to the used optical
arrangement, a 3D holoscopic imaging display presents the following advantages
compared to current stereo and multiview displays:
• An immersive 3D experience for more than one user (simultaneously) is
provided;
• Continuous motion parallax in the horizontal and vertical directions (throughout
the viewing zone) is made possible; and
• A more natural and fatigue-free 3D sensation with accurate convergence/accom-
modation and depth perception is offered to the user.
However, a critical issue, at this time, is related to the balance between the
various viewing parameters (see Fig.
5.1b
) of a 3D holoscopic display system. As
explained in [
5
], the quality of the reconstructed 3D image in a 3D holoscopic
display can be analyzed in terms of the following viewing parameters:
• Image Depth: Image depth refers to the distance between the nearest and
farthest plane where the reconstructed 3D image can be observed without severe
artifacts [
5
] (appearing with acceptable quality), as illustrated in Fig.
5.1b
.
To increase the image depth, it is necessary to reduce the pitch of the micro-
lens (see Fig.
5.1b
) and to increase the pixel size of the display. However, these
conditions lead to a narrower viewing angle and smaller viewing resolution, as
explained below.
• Viewing Angle: The viewing angle corresponds to the angular region where the
reconstructed 3D image (recreated by the display) can be seen without flipping
[
5
]. The viewing angle, as depicted in Fig.
5.1b
, determines the area (so-called
viewing zone) where the reconstructed 3D image can be observed with full
motion parallax. Moreover, the number of possible different viewpoint images is
determined by the number of pixels behind each micro-lens. As can be seen in
Fig.
5.1b
, the viewing angle is intrinsically limited by the pitch of the micro-lens
and the gap between the sensor panel and the micro-lens array. Namely, the
viewing angle increases as the pitch increases and the gap decreases. However, a
larger micro-lens pitch leads to a smaller image depth as well as a smaller
viewing resolution (as explained below).
• Viewing Resolution: The viewing resolution is the resolution of the
reconstructed 3D image (visible to the user), which is essentially limited by
the resolution of the display device and the pitch of the micro-lens. Considering
a fixed display resolution, the pitch of the micro-lens determines the fraction of
