3D Holoscopic Video Representation and Coding Technology - Novel 3D Media Technologies - page 78

Fig. 5.5 Viewpoint image based representation: (a) VI-based holoscopic image; (b) enlargement
of 272 228 pixels showing each viewpoint image in detail

x 10 4

a b

1.38
1.32

x 10 4

1.22

1.4

1.12

1.3

-MLAn MLAn

x

x 10 4

1.2

1.4

1.1 1.32

y

1.22

x

1.12

y

-MLAm MLAm

Fig. 5.6 Example of spatial correlation in a VI-based holoscopic image: (a) autocorrelation
function; and (b) projection onto x and y axis

be seen in Fig. 5.6 through the autocorrelation function, the pixel correlation in the
VI-based holoscopic image also presents a periodic structure, which is given
approximately by the resolution of each viewpoint

image (represented by

MLA n MLA m in Fig. 5.6b ).

5.3.3 Ray-Space Image Based Representation

The epipolar-plane technique [ 14 ] can be used to generate a ray-space image based
representation from the 3D holoscopic image. In this case, a ray-space image can be
formed by stacking together micro-images in the same row/column (in the array of
micro-lenses) and, then, taking a slice from a particular horizontal plane (perpen-
dicular to the micro-lens plane). For example, choosing a row k m in the array of
micro-lenses illustrated in Fig. 5.4a , and considering that the horizontal plane was