JPEG means Joint Photographic Experts Group.
X is part of JPEG standards since 2000.
L means Long-term because the authors' intention for the format is to replace the legacy JPEG and last as long too.
In 2017, JTC1/SC29/WG1 issued a Call for proposals for JPEG XL – the next generation image coding standard.
The file format (bitstream) was frozen on December 25, 2020, meaning that the format is now guaranteed to be decodable by future releases.
The main features are:
- Faster compression than H.265 HEVC HM, Daala and WebP and fast decoding;
- Support for a variety of color spaces, providing wide color gamut, higher bit depths and high dynamic ranges;
- High-quality compression of synthetic images, such as bitmap fonts and gradients;
- Inherently responsive / progressive encoding;
- Lossless encoding and lossless alpha encoding;
- Image region coding;
- Low-complexity encoding;
- Lossless transcoding of legacy JPEG images with ~20% size reduction;
- Royalty-free format with an open-source reference implementation.
JPEG XL is based on ideas from Google's Pik format and Cloudinary's FUIF format.
The format has a variety of encoding modes. On the legacy side, it has a mode that transcodes legacy JPEG in a more compact way for storage. On the more modern side, it has a VarDCT-based lossy mode (with separate modeling of shapes and repeating "patches" like text) and a near-lossless/responsive mode using a Haar-like transform. The DCT uses a XYB color space derived from LMS.
Prediction is run using a pixel-by-pixel decorrelator without side information, including a parametrized self-correcting weighted ensemble of predictors. Context modeling includes specialized static models and powerful meta-adaptive models that take local error into account, with a signalled tree structure and predictor selection per context. Entropy coding is LZ77-enabled and can use both Asymmetric Numeral Systems and Huffman coding (for low complexity encoders or for reducing overhead of short streams).
Animated (multi-frame) images do not perform inter-frame prediction – unlike the video codec-based formats.
- JPEG XL Reference Software – reference implementation
- Windows Bin Builds – convertors from the reference implementation, compiled for Windows (the page also contains many other programs)
- ImageMagick – tool set for raster graphics processing
- XnView MP – viewer and editor of raster graphics
- MConverter – online media convertor
- JPEG XL WIC – JXL support in Windows using WIC, i.e. for viewing in Photo Viewer, File Explorer etc.
- qt-jpegxl-image-plugin – JXL support for Qt on Linux
- JXLook – viewer and plugin for macOS
- Firefox – web browser
- Chromium – web browser
- WebKit – browser engine of Safari and others
- GIMP – raster graphics editor
|Common Name||Part||First public release date (First edition)||ISO/IEC Number||ITU Number||Formal Title|
|JPEG XL||Part 1||under development||ISO/IEC FDIS 18181-1||JPEG XL Image Coding System — Part 1: Core coding system|
|Part 2||under development||ISO/IEC FDIS 18181-2||JPEG XL Image Coding System — Part 2: File format|
|Part 3||under development||ISO/IEC WD 18181-3||JPEG XL Image Coding System — Part 3: Conformance testing|
|Part 4||under development||ISO/IEC CD 18181-4||JPEG XL Image Coding System — Part 4: Reference software|
- "fuif/README.md". GitHub. Retrieved 2019-04-04.
- "JPEG - Next-Generation Image Compression (JPEG XL) Final Draft Call for Proposals". Jpeg.org. April 23, 2018. Retrieved 29 May 2018.
- "v0.2 JPEG XL Reference Software". GitLab.
- "JPEG XL reaches Committee Draft". JPEG Org. 3 August 2019. Archived from the original (html) on 3 August 2019. Retrieved 3 August 2019.
The current contributors have committed to releasing it publicly under a royalty-free and open source license.
- "jpeg / JPEG XL Reference Software". GitLab.
- Alakuijala, Jyrki; van Asseldonk, Ruud; Boukortt, Sami; Szabadka, Zoltan; Bruse, Martin; Comsa, Iulia-Maria; Firsching, Moritz; Fischbacher, Thomas; Kliuchnikov, Evgenii; Gomez, Sebastian; Obryk, Robert; Potempa, Krzysztof; Rhatushnyak, Alexander; Sneyers, Jon; Szabadka, Zoltan; Vandervenne, Lode; Versari, Luca; Wassenberg, Jan (6 September 2019). Tescher, Andrew G; Ebrahimi, Touradj (eds.). "JPEG XL next-generation image compression architecture and coding tools". Applications of Digital Image Processing XLII: 20. doi:10.1117/12.2529237. ISBN 9781510629677.
- Sneyers, Jon. "How JPEG XL Compares to Other Image Codecs". Cloudinary.