|Internet media type|
|Type of format||Lossy/lossless bitmap image format|
|Open format?||Yes (royalty-free)|
JPEG XL is a royalty-free raster-graphics file format that supports both lossy and lossless compression. It is designed to outperform existing raster formats and thus to become their universal replacement.
- JPEG is the Joint Photographic Experts Group, which is the committee that designed the format.
- X is part of the name of several JPEG standards since 2000: JPEG XT, JPEG XR, JPEG XS.
- 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 (JPEG) 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.
- Improved functionality and efficiency compared to traditional image formats (e.g. JPEG, GIF and PNG);
- Image dimensions of over a billion (230-1) pixels on each side;
- Up to 4100 channels i.e grayscale or RGB, optional alpha, and up to 4096 "extra" channels;
- Progressive decoding (by resolution and precision);
- Lossless JPEG transcoding with ~20% size reduction;
- Lossless encoding and lossless alpha encoding;
- Support for both photographic and synthetic imagery;
- Graceful quality degradation across a large range of bitrates;
- Perceptually optimized reference encoder;
- Support for wide color gamut and HDR;
- Support for animated content,
- Efficient encoding and decoding without requiring specialized hardware
- Royalty-free format with an open-source reference implementation.
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 lossy mode called VarDCT (variable-blocksize DCT) and a lossless/near-lossless/responsive mode called Modular which optionally uses a modified Haar transform (called "squeeze") and which is also used to encode the DC (1:8 scale) image in VarDCT mode as well as various auxiliary images such as adaptive quantization fields or additional channels like alpha. Both modes can use separate modeling of specific image features: splines, repeating "patches" like text or dots, and noise synthesis. Lossy modes typically use the 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 advanced inter-frame prediction, though some rudimentary inter-frame coding tools are available:
- a frame can only update part of the canvas;
- a frame can not just replace the contents on the canvas, but also be blended, added or multiplied to it;
- up to three frames can be 'remembered' and referenced using the "patches" coding tool in later frames.
|Initial release||December 27, 2019|
0.3.7 / March 29, 2021
|License||New BSD License (previously Apache License 2.0)|
- JPEG XL Reference Software (libjxl)
- ImageMagick – toolkit for raster graphics processing
- XnView MP – viewer and editor of raster graphics
- MConverter – online media converter
- Squoosh – WebAssembly-based image converter (online media converter available)
- nomacs – free and open-source cross operating system image viewer, also offers minor editing features
- gThumb – free Linux image viewer
- ImageGlass – free and open-source Windows image viewer
- Qt / KDE apps – via plugin
- Microsoft Windows – via WIC plugin, i.e. for viewing in Photo Viewer, File Explorer etc.
- macOS – via standalone app and Quick Look plugin
- GIMP – raster graphics editor; plugin for GIMP 2.10 available
- Chromium – web browser; in testing (as Chrome Beta and Edge Canary)
- Firefox – web browser; in testing (as Firefox Nightly)
|Common Name||Part||First public release date (First edition)||ISO/IEC Number||Formal Title|
|JPEG XL||Part 1||under development, planned for 2021||ISO/IEC FDIS 18181-1||JPEG XL Image Coding System — Part 1: Core coding system|
|Part 2||under development, planned for 2021||ISO/IEC DIS 18181-2||JPEG XL Image Coding System — Part 2: File format|
|Part 3||under development, planned for 2022||ISO/IEC WD 18181-3||JPEG XL Image Coding System — Part 3: Conformance testing|
|Part 4||under development, planned for 2022||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 XL White Paper" (PDF). JPEG Org. 22 January 2021. Retrieved 17 March 2021.
- Sneyers, Jon. "How JPEG XL Compares to Other Image Codecs". Cloudinary.
- Jon Sneyers (2021-01-03). "JPEG XL as PSD transfer/storage alternative". Reddit.
- Jon Sneyers (2021-06-03). "Progressive Transcoding". GitHub.
- "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.
- "PLEASE DO NOT OPEN NEW ISSUES HERE". Retrieved 27 May 2021.