3D image reconstruction with controllable spatial
filtering based on correlation of multiple periodic
functions in computational integral imaging
Jae-Young Jang
1
, Myungjin Cho
2,
*, and Eun-Soo Kim
1
1
Department of Optometry, Eulji University, 553, Sanseong-daero, Sujeong-gu, Seongnam-si, Gyonggi-do, South Korea
2
Department of Electrical, Electronic, and Control Engineering, Hankyong National University,
Kyonggi-do 456-749, South Korea
*Corresponding author: mjcho@hknu.ac.kr
Received November 2, 2014; accepted December 22, 2014; posted online March 2, 2015
We propose a novel method of slice image reconstruction with controllable spatial filtering by using the corre-
lation of periodic delta-function arrays (PDFAs) with elemental images in computational integral imaging. The
multiple PDFAs, whose spatial periods correspond to object’ s depths with the elemental image array (EIA), can
generate a set of spatially filtered EIAs for multiple object depths compared with the conventional method
for the depth of a single object. We analyze a controllable spatial filtering effect by the proposed method.
To show the feasibility of the proposed method, we carry out preliminary experiments for multiple objects
and present the results.
OCIS codes: 110.6880, 110.4190.
doi: 10.3788/COL201513.031101.
Computational integral imaging (CII) is capable of
extracting 3D information for occluded 3D objects
[1–15]
.
In general, it is divided into two parts: pickup and com-
putational recon struction. In the pickup part, a set of 2D
images with different perspectives of the 3D objects can be
captured as elemental images through a lens array. From
this captured elemental image array (EIA), the digital
reconstruction part generates a set of slice images using
a computational reconstruction technique based on simu-
lated ray-optics. According to the reconstruction algo-
rithm, the slice images were generated with different
resolutions and viewing angles
[4–7,16–20]
. Among them, one
method is to use the reconstruction of the volume pixels
of the scene by computationally simulating optical
reconstruction in accordance with ray optics
[4]
. Another
method is based on rearrangement of pixels in the elemen-
tal image to reconstruct slice image with improved reso-
lution
[17]
. Recently, a depth extraction method by using
the periodic delta-function array (PDFA) in CII was
proposed
[18–20]
. In this method, this PDFA can also
generate the perspective slice image array with depth-
dependent spatial filtering. This method can be applied
to several applications including depth extraction, parti-
ally occluded 3D object reconstruction, optical refocusing
display, and so on
[19,20]
.
In this Letter, to improve the performance of the con-
ventional PDFA-based CII, we propose a novel method of
slice image reconstruction with controllable spatial filter-
ing by using the correlation of PDFAs with elemental
images in CII. The multiple PDFAs are generated with
spatial periods corresponding to object’s depths in accor-
dance with the EIA. They are used to generate a set of
spatially filtered EIAs for multiple object depths com-
pared with the conventional method for a single object
depth. We analyze a spatial filtering effect by the pro-
posed method and carry out preliminary experiments.
Before we explain the proposed method, we first present
the spatial period in the pickup process. The process of
capturing elemental images by the direct pickup method
in the integral imaging system is based on ray optics. In
the direct pickup method, the location of the pickup device
may be considered for the imaging points of elemental
images on the pickup sensor as shown in Fig.
1.
Let us consid er that the rays emitted from the point ob-
ject pass through the optical center of a pickup device’s
lens. The geometrical relation between a point object,
its corresponding points on the lens array, and location
of pickup device can be given by
x
0
En
¼
x
O
þ
z
O
z
O
þ f
n −
1
2
P − x
O
þ
z
O
f
z
O
f þ dðz
O
þ f Þ
×
x
d
−
x
O
þ
z
O
z
O
þ f
n −
1
2
P − x
O
: (1)
In Fig.
1 and Eq. (1), the origin of the coordinate system
is the edge of the elemental lens located at the bottom of
the lens array. z
O
and x
O
represent the positions of the
point object along the z- and x-axes, respec tively. P
represents the distance between the centers of the
neighboring elemental lenses as well as the diameter of
a single elemental lens. f denotes the focal length of an
elemental lens. In addition, x
0
En
represents a point on
the nth elemental lens, in which the valid x
0
En
is restricted
by ðn − 1ÞP ≤ x
0
En
≤ nP in the direct pickup condition
and n means the natural number. d and x
d
represent
COL 13(3), 031101(2015) CHINESE OPTICS LETTERS March 10, 2015
1671-7694/2015/031101(5) 031101-1 © 2015 Chinese Optics Letters