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IEICE TRANSACTIONS on Fundamentals

Open Access
Good Group Sparsity Prior for Light Field Interpolation

Shu FUJITA, Keita TAKAHASHI, Toshiaki FUJII

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Summary :

A light field, which is equivalent to a dense set of multi-view images, has various applications such as depth estimation and 3D display. One of the essential problems in light field applications is light field interpolation, i.e., view interpolation. The interpolation accuracy is enhanced by exploiting an inherent property of a light field. One example is that an epipolar plane image (EPI), which is a 2D subset of the 4D light field, consists of many lines, and these lines have almost the same slope in a local region. This structure induces a sparse representation in the frequency domain, where most of the energy resides on a line passing through the origin. On the basis of this observation, we propose a group sparsity prior suitable for light fields to exploit their line structure fully for interpolation. Specifically, we designed the directional groups in the discrete Fourier transform (DFT) domain so that the groups can represent the concentration of the energy, and we thereby formulated an LF interpolation problem as an overlapping group lasso. We also introduce several techniques to improve the interpolation accuracy such as applying a window function, determining group weights, expanding processing blocks, and merging blocks. Our experimental results show that the proposed method can achieve better or comparable quality as compared to state-of-the-art LF interpolation methods such as convolutional neural network (CNN)-based methods.

Publication
IEICE TRANSACTIONS on Fundamentals Vol.E103-A No.1 pp.346-355
Publication Date
2020/01/01
Publicized
Online ISSN
1745-1337
DOI
10.1587/transfun.2018EAP1175
Type of Manuscript
PAPER
Category
Image

Authors

Shu FUJITA
  Nagoya University
Keita TAKAHASHI
  Nagoya University
Toshiaki FUJII
  Nagoya University

Keyword