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JOIG 2024 Vol.12(1): 90-102
doi: 10.18178/joig.12.1.90-102

Super-Rays Grouping Scheme and Novel Coding Architecture for Computational Time Reduction of Graph-Based Light Field Coding

Nguyen Gia Bach 1, Chanh Minh Tran 1, Nguyen Duc Tho 1, Phan Xuan Tan 2,*, and Eiji Kamioka 1
1. Graduate School of Engineering and Science, Shibaura Institute of Technology, Tokyo, Japan
2. Department of Information and Communications Engineering, Shibaura Institute of Technology, Tokyo, Japan
Email: nb23505@shibaura-it.ac.jp (N.G.B.); nb20502@shibaura-it.ac.jp (C.M.T.);
nb20501@shibaura-it.ac.jp (T.N.D.); tanpx@shibaura-it.ac.jp (P.X.T.);
kamioka@shibaura-it.ac.jp (E.K.) *Corresponding author

Manuscript received October 10, 2023; revised November 24, 2023; accepted December 5, 2023; March 21, 2024

Abstract—Graph-based Light Field coding using the concept of super-rays is powerful to exploit signal redundancy along irregular shapes and achieves good energy compaction, compared to rectangular block -based approaches. However, its main limitation lies in the high time complexity for eigen-decomposition of each super-ray local graph, a high number of which can be found in a Light Field when segmented into super-rays. This paper examines a grouping scheme for super-rays in order to reduce the number of eigen-decomposition times, and proposes a novel coding architecture to handle the signal residual data arising for each super-ray group, as a tradeoff to achieve lower computational time. Experimental results have shown to reduce a considerable amount of decoding time for Light Field scenes, despite having a slight increase in the coding bitrates when compared with the original non-grouping super-ray-based approach. The proposal also remains to have competitive performance in Rate Distortion in comparison to HEVC-based and JPEG Pleno -based methods.

Keywords—light field, compression, super-ray, over-segmentation, graph transform, eigen-decomposition

Cite: Nguyen Gia Bach, Chanh Minh Tran, Nguyen Duc Tho, Phan Xuan Tan, and Eiji Kamioka, "Super-Rays Grouping Scheme and Novel Coding Architecture for Computational Time Reduction of Graph-Based Light Field Coding," Journal of Image and Graphics, Vol. 12, No. 1, pp. 90-102, 2024.

Copyright © 2024 by the authors. This is an open access article distributed under the Creative Commons Attribution License (CC BY-NC-ND 4.0), which permits use, distribution and reproduction in any medium, provided that the article is properly cited, the use is non-commercial and no modifications or adaptations are made.