JPEG to 3D: A Case for Holography Standardization
Scientists discuss the requirements laid down by the JPEG committee for holography standardization and the challenges involved in meeting them.
Among the various imaging modalities that have recently emerged, holography is the most challenging to standardize due to its varying technological maturity and market success. The JPEG committee has launched an initiative that attempts to lay down a set of requirements for holography standardization. A recent paper in the ETRI Journal highlights these requirements and the challenges that need to be overcome for optimum interoperability between different holographic applications.
One of the most known digital file formats that we use today to store, display, process, and deliver electronic images is the JPEG. What is much less commonly known is that the name JPEG evolved from the “Joint Photographic Experts Group,” which created the file format. The JPEG committee regularly issues image coding standards — processes for image representation — to deal with the burgeoning imaging market that has given rise to all kinds of novel imaging techniques.
Recently, the committee has launched a standardization initiative to address a rapidly emerging image paradigm where they are no longer a “2D” concept but rather a “3D volumetric” concept. Named JPEG Pleno (from plenoptic, a mathematical model that calculates light intensity at a point in space, accounting for the direction of light rays), the initiative emphasizes 3D imaging modalities like “light fields,” “point clouds,” and “holography” and aims to provide a standard framework that will facilitate their capture, representation, and exchange.
However, not all modalities can be standardized at the same speed due to the varying industrial needs and technological maturity. Holography is perhaps the most challenging to standardize. In a recent paper published in the ETRI journal, a team of scientists from Europe and Korea focuses on these challenges and outlines the measures adopted to address them. “One of the main challenges associated with standardizing holography is the variation in its technological maturity depending on the use case. So, we outlined its main use cases coupled with a list of requirements for its standardization”, says Prof. Peter Schelkens from Vrije Universiteit Brussel, Belgium who led the study.
Holography’s maturity as a technology has been variable. For instance, applications like holographic microscopy and holographic interferometry have found use in scientific research, medicine, and industry while holographic printing and display are still in their infancy. What is common to all, however, is a need for efficient coding to enable storage and transmission of large amounts of data.
Accordingly, the JPEG committee has created a list of requirements pertaining to holographic coding technology that range from complex amplitude representation (a mathematical model that accounts for both amplitude and phase of the wave), compression efficiency, to perceptual quality control. In addition, the committee has liaised with other organizations addressing the holography field in an attempt to facilitate interoperability and content exchange between various applications.
However, meeting these requirements is not without its challenges; all attempts to efficiently compress hologram data, for instance, have only been partially successful, while no solutions have so far been presented for perceptual quality metrics appropriate for hologram data. So, we need reliable quality assessment procedures and strategies to make meaningful decisions throughout the standardization process.
As a next step, JPEG experts are therefore looking for suitable coding technology and potential contributors. In addition, the team, in their paper, invites interested parties to join this process. “Despite all the setbacks and challenges, we have been able to lay down an appropriate protocol for hologram standardization. Also, to be fair, the coding technologies have only evolved at par with the use cases. We can certainly hope for better as digital holography matures more as a technology” , concludes Prof. Schelkens.
Reference
Titles of original papers: JPEG Pleno: Providing representation interoperability for holographic applications and devices
Name of author:
Peter Schelkens1,2, Touradj Ebrahimi3, Antonin Gilles4, Patrick Gioia4,5, Kwan-Jung Oh6,Fernando Pereira7,Cristian Perra8,and Antonio M.G. Pinheiro9
Affiliation:
1Department of Electronics and Informatics, Vrije Universiteit Brussel
2Digital and User-centric Solutions, IMEC
3Multimedia Signal Processing Group, Ecole Polytechnique Fédérale de Lausanne
4Institute of Research & Technology b<>com
5Orange Labs
6Broadcasting & Media Research Laboratory, Electronics and Telecommunications Research Institute
7Instituto Superior Técnico, Universidade de Lisboa — Instituto de Telecommunicações
8Department of Electrical and Electronic Engineering, UdR CNIT, University of Cagliari
9Universidade da Beira Interior and Instituto de Telecommunicações
About Professor Peter Schelkens
Peter Schelkens holds a professorship with the Department of Electronics and Informatics, Vrije Universiteit Brussel, Belgium and is a Research Group Leader at IMEC, Belgium. In 2013, he received an EU ERC Consolidator Grant focusing on digital holography. He is the co-editor of the books The JPEG 2000 Suite (Wiley, 2009) and Optical and Digital Image Processing (Wiley, 2011). He is chair of the Coding, Test and Quality subgroup of the ISO/IEC JTC1/SC29/WG1 (JPEG) standardization committee and Associate Editor for the IEEE Transactions on Circuits and Systems for Video Technology, and Signal Processing: Image Communications.
