On September 5th 2018 the paper "Rate Distortion Optimized Graph Partitioning for Omnidirectional Image Coding" authored by Mira Rizkallah (INRIA), Francesca De Simone (CWI), Thomas Maugey (INRIA), Christine Guillemot (INRIA), and Pascal Frossard (EPFL), has been awarded with the Best Student Paper Award at the 26th edition of the European Signal Processing Conference (EUSIPCO).
Omnidirectional images are spherical signals captured by cameras with 360-degree field of view. In order to be compressed using existing encoders, these signals are mapped to the planar domain. A commonly used planar representation is the equirectangular one, which corresponds to a non uniform sampling pattern on the spherical surface. This particularity is not explored in traditional image compression schemes, which treat the input signal as a classical perspective image. In this work, we build a graph-based coder adapted to the spherical surface. We build a graph directly on the sphere. Then, to have computationally feasible graph transforms, we propose a rate-distortion optimized graph partitioning algorithm to achieve an effective trade-off between the distortion of the reconstructed signals, the smoothness of the signal on each subgraph, and the cost of coding the graph partitioning description. Experimental results demonstrate that our method outperforms JPEG coding of planar equirectangular images.
Francesca De Simone has joined CWI’s Distributed and Interactive Systems (DIS) research group as tenure track researcher on February 2018. Research at DIS focuses on facilitating and improving the way people access media and communicate with others and with the environment. They address key problems for society and science, resulting from the dense connectivity of content, people, and devices. The group uses recognized scientific methods, following a full-stack, experimental, and human-centered approach.
More information:
EUSIPCO 2018
Francesca De Simone
DIS group
Omnidirectional images are spherical signals captured by cameras with 360-degree field of view. In order to be compressed using existing encoders, these signals are mapped to the planar domain. A commonly used planar representation is the equirectangular one, which corresponds to a non uniform sampling pattern on the spherical surface. This particularity is not explored in traditional image compression schemes, which treat the input signal as a classical perspective image. In this work, we build a graph-based coder adapted to the spherical surface. We build a graph directly on the sphere. Then, to have computationally feasible graph transforms, we propose a rate-distortion optimized graph partitioning algorithm to achieve an effective trade-off between the distortion of the reconstructed signals, the smoothness of the signal on each subgraph, and the cost of coding the graph partitioning description. Experimental results demonstrate that our method outperforms JPEG coding of planar equirectangular images.
Francesca De Simone has joined CWI’s Distributed and Interactive Systems (DIS) research group as tenure track researcher on February 2018. Research at DIS focuses on facilitating and improving the way people access media and communicate with others and with the environment. They address key problems for society and science, resulting from the dense connectivity of content, people, and devices. The group uses recognized scientific methods, following a full-stack, experimental, and human-centered approach.
More information:
EUSIPCO 2018
Francesca De Simone
DIS group
