JPEG Column: 104th JPEG Meeting in Sapporo, Japan

Author: Antonio Pinheiro
Affiliation: Instituto de Telecomunicacoes (IT) and Universidade da Beira Interior (UBI), Covilha, Portugal

JPEG XE issues Call for Proposals on event-based vision representation

The 104th JPEG meeting was held in Sapporo, Japan from July 15 to 19, 2024. During this JPEG meeting, a Call for Proposals on event-based vision representation was launched for the creation of the first standardised representation of this type of data. This CfP addresses lossless coding, and aims to provide the first standard representation for event-based data that ensures interoperability between systems and devices.

Furthermore, the JPEG Committee pursued its work in various standardisation activities, particularly the development of new learning-based technology codecs and JPEG Trust.

The following summarises the main highlights of the 104th JPEG meeting.

Event based vision reconstruction (from IEEE Spectrum, Feb. 2020).
  • JPEG XE
  • JPEG Trust
  • JPEG AI
  • JPEG Pleno Learning-based Point Cloud coding
  • JPEG Pleno Light Field
  • JPEG AIC
  • JPEG Systems
  • JPEG DNA
  • JPEG XS
  • JPEG XL

JPEG XE

The JPEG Committee continued its activity on JPEG XE and event-based vision. This activity revolves around a new and emerging image modality created by event-based visual sensors. JPEG XE is about the creation and development of a standard to represent events in an efficient way allowing interoperability between sensing, storage, and processing, targeting machine vision and other relevant applications. The JPEG Committee completed the Common Test Conditions (CTC) v2.0 document that provides the means to perform an evaluation of candidate technologies for efficient coding of events. The Common Test Conditions document also defines a canonical raw event format, a reference dataset, a set of key performance metrics and an evaluation methodology.

The JPEG Committee furthermore issued a Final Call for Proposals (CfP) on lossless coding for event-based data. This call marks an important milestone in the standardization process and the JPEG Committee is eager to receive proposals. The deadline for submission of proposals is set to March 31st of 2025. Standardization will start with lossless coding of events as this has the most imminent application urgency in industry. However, the JPEG Committee acknowledges that lossy coding of events is also a valuable feature, which will be addressed at a later stage.

Accompanying these two new public documents, a revised Use Cases and Requirements v2.0 document was also released to provide a formal definition for lossless coding of events that is used in the CTC and the CfP.

All documents are publicly available on jpeg.org. The Ad-hoc Group on event-based vision was re-established to continue work towards the 105th JPEG meeting. To stay informed about this activity please join the event-based vision Ad-hoc Group mailing list.

JPEG Trust

JPEG Trust provides a comprehensive framework for individuals, organizations, and governing institutions interested in establishing an environment of trust for the media that they use, and supports trust in the media they share. At the 104th meeting, the JPEG Committee produced an updated version of the Use Cases and Requirements for JPEG Trust (v3.0). This document integrates additional use cases and requirements related to authorship, ownership, and rights declaration. The JPEG Committee also requested a new Part to JPEG Trust, entitled “Media asset watermarking”. This new Part will define the use of watermarking as one of the available components of the JPEG Trust framework to support usage scenarios for content authenticity, provenance, integrity, labeling, and binding between JPEG Trust metadata and corresponding media assets. This work will focus on various types of watermarking, including explicit or visible watermarking, invisible watermarking, and implicit watermarking of the media assets with relevant metadata.

JPEG AI

At the 104th meeting, the JPEG Committee reviewed recent integration efforts, following the adoption of the changes in the past meeting and the creation of a new version of the JPEG AI verification model. This version reflects the JPEG AI DIS text and was thoroughly evaluated for performance and functionalities, including bitrate matching, 4:2:0 coding, region adaptive quantization maps, and other key features. JPEG AI supports a multi-branch coding architecture with two encoders and three decoders, allowing for six compatible combinations that have been jointly trained. The compression efficiency improvements range from 12% to 27% over the VVC Intra coding anchor, with decoding complexities between 8 to 215 kMAC/px.

The meeting also focused on Part 2: Profiles and Levels, which is moving to Committee Draft consultation. Two main concepts have been established: 1) the stream profile, defining a specific subset of the code stream syntax along with permissible parameter values, and 2) the decoder profile, specifying a subset of the full JPEG AI decoder toolset required to obtain the decoded image. Additionally, Part 3: Reference Software and Part 5: File Format will also proceed to Committee Draft consultation. Part 4 is significant as it sets the conformance points for JPEG AI compliance, and some preliminary experiments have been conducted in this area.

JPEG Pleno Learning-based Point Cloud coding

Learning-based solutions are the state of the art for several computer vision tasks, such as those requiring high-level understanding of image semantics, e.g., image classification, face recognition and object segmentation, but also 3D processing tasks, e.g. visual enhancement and super-resolution. Learning-based point cloud coding solutions have demonstrated the ability to achieve competitive compression efficiency compared to available conventional point cloud coding solutions at equivalent subjective quality. At the 104th meeting, the JPEG Committee instigated balloting for the Draft International Standard (DIS) of ISO/IEC 21794 Information technology — Plenoptic image coding system (JPEG Pleno) — Part 6: Learning-based point cloud coding. This activity is on track for the publication of an International Standard in January 2025. The 104th meeting also began an exploration into advanced point cloud coding functionality, in particular the potential for progressive decoding of point clouds.

JPEG Pleno Light Field

The JPEG Pleno Light Field effort has an ongoing standardization activity concerning a novel light field coding architecture that delivers a single coding mode to efficiently code light fields spanning from narrow to wide baselines. This novel coding mode is depth information agnostic resulting in significant improvement in compression efficiency. The first version of the Working Draft of the JPEG Pleno Part 2: Light Field Coding second edition (ISO/IEC 21794-2 2ED), including this novel coding mode, was issued during the 104th JPEG meeting in Sapporo, Japan.

The JPEG PLeno Model (JPLM) provides reference implementations for the standardized technologies within the JPEG Pleno framework, including the JPEG Pleno Part 2 (ISO/IEC 21794-2). Improvements to the JPLM have been implemented and tested, including the design of a more user-friendly platform.

The JPEG Pleno Light Field effort is also preparing standardization activities in the domains of objective and subjective quality assessment for light fields, aiming to address other plenoptic modalities in the future. During the 104th JPEG meeting in Sapporo, Japan, the collaborative subjective experiments aiming at exploring various aspects of subjective light field quality assessments were presented and discussed. The outcomes of these experiments will guide the decisions during the subjective quality assessment standardization process, which has issued its third Working Draft. A new version of a specialized tool for subjective quality evaluation, that supports these experiments, has also been released.

JPEG AIC

At its 104th meeting, the JPEG Committee reviewed results from previous Core Experiments that collected subjective data for fine-grained quality assessments of compressed images ranging from high to near-lossless visual quality. These crowdsourcing experiments used triplet comparisons with and without boosted distortions, as well as double stimulus ratings on a visual analog scale. Analysis revealed that boosting increased the precision of reconstructed scale values by nearly a factor of two. Consequently, the JPEG Committee has decided to use triplet comparisons in the upcoming AIC-3.

The JPEG Committee also discussed JPEG AIC Part 4, which focuses on objective image quality assessments for compressed images in the high to near-lossless quality range. This includes developing methods to evaluate the performance of such objective image quality metrics. A draft call for contributions is planned for January 2025.

JPEG Systems

At the 104th meeting Part 10 of JPEG Systems (ISO/IEC 19566-10), the JPEG Systems Reference Software, reached the IS stage. This first version of the reference software provides a reference implementation and reference dataset for the JPEG Universal Metadata Box Format (JUMBF, ISO/IEC 19566-5). Meanwhile, work is in progress to extend the reference software implementations of additional Parts, including JPEG Privacy and Security and JPEG 360.

JPEG DNA

JPEG DNA is an initiative aimed at developing a standard capable of representing bi-level, continuous-tone grey-scale, continuous-tone colour, or multichannel digital samples in a format using nucleotide sequences to support DNA storage. A Call for Proposals was published at the 99th JPEG meeting. Based on the performance assessments and descriptive analyses of the submitted solutions, the JPEG DNA Verification Model was created during the 102nd JPEG meeting. Several core experiments were conducted to validate this Verification Model, leading to the creation of the first Working Draft of JPEG DNA during the 103rd JPEG meeting.

The next phase of this work involves newly defined core experiments to enhance the rate-distortion performance of the Verification Model and its robustness to insertion, deletion, and substitution errors. Additionally, core experiments to test robustness against substitution and indel noise are conducted. A core experiment was also performed to integrate JPEG AI into the JPEG DNA VM, and quality comparisons have been carried out. A study on visual quality assessment of JPEG AI as an alternative to JPEG XL in the VM will be carried out.

In parallel, efforts are underway to improve the noise simulator developed at the 102nd JPEG meeting, enabling a more realistic assessment of the Verification Model’s resilience to noise. There is also ongoing exploration of the performance of different clustering and consensus algorithms to further enhance the VM’s capabilities.

JPEG XS

The core parts of JPEG XS 3rd edition were prepared for immediate publication as International Standards. This means that Part 1 of the standard – Core coding tools, Part 2 – Profiles and buffer models, and Part 3 – Transport and container formats, will be available before the end of 2024. Part 4 – Conformance testing is currently still under DIS ballot and it will be finalized in October 2024. At the 104th meeting, the JPEG Committee continued the work on Part 5 – Reference software. This part is currently at Committee Draft stage and the DIS is planned for October 2024. The reference software has a feature-complete decoder that is fully compliant with the 3rd edition. Work on the encoder is ongoing.

Finally, additional experimental results were presented on how JPEG XS can be used over 5G mobile networks for wireless transmission of low-latency and high quality 6K/8K 360 degree views with mobile devices and VR headsets. This work will be continued.

JPEG XL

Objective metrics results for HDR images were investigated (using among others the ColorVideoVDP metric), indicating very promising compression performance of JPEG XL compared to other codecs like AVIF and JPEG 2000. Both the libjxl reference software encoder and a simulated candidate hardware encoder were tested. Subjective experiments for HDR images are planned.

The second editions of JPEG XL Part 1 (Core coding system) and Part 2 (File format) are now ready for publication. The second edition of JPEG XL Part 3 (Conformance testing) has moved to the FDIS stage.

Final Quote

“The JPEG Committee has reached a new milestone by releasing a new Call for Proposals to code events. This call is aimed at creating the first International Standard to efficiently represent events, enabling interoperability between devices and systems that rely on event sensing.” said Prof. Touradj Ebrahimi, the Convenor of the JPEG Committee.

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