Compression and visual quality assessment for light field contents

Staff - Faculty of Informatics

Date: 24 May 2019 / 13:30 - 14:30

USI Lugano Campus, room SI-004, Informatics building (Via G. Buffi 13)

Irene Viola, École polytechnique fédérale de Lausanne (EPFL), Switzerland

Light field photography aims at overcoming the limitations of traditional photography by recording the direction of light along with its intensity. However, a considerably larger volume of data is generated when compared to traditional photography. Thus, new and efficient compression algorithms are needed to sensibly reduce the amount of data that needs to be stored and transmitted, while maintaining an adequate level of perceptual quality.
In designing new solutions to address the unique challenges posed by light field photography, one cannot forgo the importance of having reliable, reproducible means of evaluating their performance, especially in relation to the scenario in which they will be consumed.
To that end, subjective assessment of visual quality is of paramount importance to evaluate the impact of compression, representation, and rendering models on user experience. However, new subjective methodologies are needed to be tailored for the new possibilities this new type of imaging offers in terms of rendering and visual experience.
In this talk, the aforementioned problems will be addressed by presenting new methodologies for visual quality evaluation of light field contents, and outlining a new compression solution to efficiently reduce the amount of data that needs to be transmitted and stored. We will first analyze how traditional methodologies for subjective evaluation of multimedia contents can be adapted to suit light field data, and, we will propose new methodologies to reliably assess the visual quality while maintaining user engagement.
Furthermore, we will study how user behavior is affected by the visual quality of the data. We will employ subjective quality assessment to compare several state-of-the-art solutions in light field coding, in order to find the most promising approaches to minimize the volume of data without compromising on the perceptual quality. To that means, we will define and inspect several coding approaches for light field compression, and we will investigate the impact of color subsampling on the final rendered content. Lastly, we will propose a new coding approach to perform light field compression, showing significant improvement with respect to the state of the art.

Irene Viola is a postdoctoral researcher at the Swiss Federal Institute of Technology in Lausanne (EPFL). She received a B.Sc. in Cinema and Media Engineering and a M.Sc. degree in Computer Engineering from the Polytechnic University of Turin, Italy, in 2013 and 2015, respectively. In 2019 she obtained a PhD in Electrical Engineering from EPFL, under the supervision of Prof. Touradj Ebrahimi. Her research interest include immersive media technologies, in particular light field and point cloud imaging, image and video compression, and quality of experience.

Host: Prof. Piotr Didyk