JPEG XL


The JPEG XL 'Image Coding System' is an image format that supports both lossy and lossless compression. It was developed by the Joint Photographic Experts Group, Google and Cloudinary. It is a free and open standard defined by ISO/IEC 18181. The standard consists of four parts that cover the Core coding system, File format, Conformance testing, and Reference software, respectively.
JPEG XL features a lossy compression mode called VarDCT built on block-based transform coding, which is similar to — but significantly improves and expands upon — the compression method of JPEG, and a modular mode that allows different features of the format to be combined in a "modular" way. Modular mode can be used either for lossless image compression, similar to PNG, or as a means to achieve lossy compression in a different way from VarDCT.
The name refers to the design committee, the X designates the series of its image coding standards published since 2000, and L stands for "long-term", highlighting the intent to create a future-proof, long-lived format to succeed JPEG/JFIF.
The main authors of the specification are Jyrki Alakuijala, Jon Sneyers, Zoltan Szabadka, and Luca Versari. Other collaborators are Sami Boukortt, Alex Deymo, Moritz Firsching, Thomas Fischbacher, Eugene Kliuchnikov, Robert Obryk, Alexander Rhatushnyak, Lode Vandevenne, and Jan Wassenberg.

Positioning

JPEG XL was designed to become a universal replacement for all established raster formats for the Web.
To reach widespread adoption, the designers hope for beneficial network effects by offering the single best option for as many popular use cases as possible.
To that end the format offers significant improvements over all other options with a comprehensive set of useful properties, geared especially towards accessibility over the Web and a smooth upgrade path, in combination with uncompromisingly powerful, yet efficiently computable compression and efficient data representation. Following a study about the most popular JPEG quality on the Web, developers paid special attention to the range with negligible or no perceived loss, and the default settings were adjusted accordingly. Several serious attempts at replacing JPEG that provided poor support for the high end of the quality range have failed.
The JPEG XL call for proposals talks about the requirement of substantially better compression efficiency comparing to JPEG. The standard is expected to outperform the still image compression performance shown by HEIC, AVIF, WebP, and JPEG 2000.

History

In 2015, Jon Sneyers of the company Cloudinary published his Free Lossless Image Format on which he based his standardization proposal, called the Free Universal Image Format, that begot JXL's "modular mode".
In 2017 Google's data compression research team in Zurich published the PIK format, the prototype for the frequency transform coding mode.
In 2018, the Joint Photographic Experts Group published a call for proposals for JPEG XL, its next-generation image coding standard. The proposals were submitted by September 2018. From seven proposals, the committee selected two as the starting point for the development of the new format: FUIF and PIK. In July 2019 the committee published a draft, mainly based on a combination of the two proposals. The bitstream was informally frozen on 24 December 2020 with the release of version 0.2 of the libjxl reference software.
The file format and core coding system were formally standardized on 13 October 2021 and 30 March 2022 respectively.

Industry support and adoption

Besides Cloudinary, throughout JPEG XL's preliminary implementation in web browsers, various representatives of well-known industry brand names have publicly voiced support for JPEG XL as their preferred choice, including Facebook, Adobe, Intel, the Video Electronics Standards Association, The Guardian, Flickr, SmugMug, Shopify, the Krita Foundation, and Serif Ltd.
Google's stance on JPEG XL was historically ambiguous, as it contributed to the format but refrained from shipping an implementation of it in its browser. Support in Chromium and Chrome web browsers was introduced for testing April 1, 2021 and removed on December 9, 2022 – with support removed in version 110. The Chrome team cited a lack of interest from the ecosystem, insufficient improvements, and a wish to focus on improving existing formats as reasons for removing JPEG XL support.
The decision was met with opposition from the community, with many voicing support for JPEG XL on Chromium's bug tracker. Jon Sneyers, co-author of the JPEG XL spec, has questioned the conclusions drawn by the Chrome team, saying: "I think there has been an unfortunate misinterpretation of the data... which has unfortunately led to an incorrect decision." The decision was also criticized by Greg Farough from the Free Software Foundation, who said it demonstrated Google's "disturbing amount of control" over the web and web browsers.
In November 2025, the Chrome team reverted their stance on JPEG XL and announced that it was open to contributions to integrate a memory safe and performant decoder in Blink. The team would require the decoder implementation to have commitment to long-term maintenance to ship it in Chrome. In January 2026, JPEG XL decoding support was merged into Chromium.
Mozilla expressed security concerns, as they feel that the rather bulky reference decoder would add a substantial amount of attack surface to Firefox. They expressed willingness to ship a decoder that meets their criteria if someone provides and integrates a suitable implementation. The JPEG XL team at Google Research has offered to write a decoder using the Rust programming language but maintains neutral position on supporting JPEG XL.
An extension to enable JPEG XL support in Chrome and Firefox became available in January 2024.
Apple Inc. included native JPEG XL file support starting with iOS/iPadOS 17, macOS 14 Sonoma, and Safari 17. iPhone 16 Pro supports JPEG XL compression when capturing ProRAW photos.
Microsoft added support for opening and saving JPEG XL files for Windows 11 24H2 via the JPEG XL image extension in Microsoft Store. Also Microsoft Photos added native JPEG XL support in the 2025.11030.20006.0 build.
The raw image format Digital Negative allows image data contained within to be compressed using JPEG XL. Starting in version 1.7.0.0 from June 2023, JPEG XL compression was included as part of the specification. This created a basis for later use as part of "Expert RAW" in Samsung Galaxy smartphones and Apple's "ProRAW".
The PDF Association has stated in the PDF Days Europe 2025 event that they selected JPEG XL as the preferred image format for HDR images embedded for PDF, although no timeline has been given.

Standardization status

Common namePartFirst public release date
ISO/IEC NumberFormal Title
JPEG XLPart 130 March 2022JPEG XL Image Coding System — Part 1: Core coding system
JPEG XLPart 213 October 2021JPEG XL Image Coding System — Part 2: File format
JPEG XLPart 33 October 2022JPEG XL Image Coding System — Part 3: Conformance testing
JPEG XLPart 45 August 2022JPEG XL Image Coding System — Part 4: Reference software

Features

JPEG XL has features aimed at web delivery such as advanced progressive decoding, embedded previews, and minimal header overhead, as well as features aimed at image editing and digital printing, such as support for multiple layers, CMYK, and spot colors. It also supports animated images.
The main features are:

Compression:
  • Lossless encoding for any channel, including alpha.
  • Support for both photographic and synthetic imagery: The format features two complementary modes that can be used depending on the image contents.
  • Computationally efficient encoding and decoding without requiring specialized hardware: JPEG XL is about as fast to encode and decode as old JPEG using libjpeg-turbo and an order of magnitude faster to encode and decode compared to HEIC with x265.
  • It is also parallelizable.
Data reduction:
  • Lossy compression is supported through the optional quantization of transform coefficients.
  • High image fidelity is well supported.
  • Graceful quality degradation across a large range of bitrates: Quality loss isn't as abrupt as with older formats.
  • Perceptually optimized reference encoder which uses a perceptual color space, and adaptive quantization.
Versatile and future-proof size limits:
  • JPEG XL supports ultra-high-resolution images with dimensions of over a billion pixels per side,
  • sample precision of up to 32 bits, e.g. for HDR content.
  • up to 4099 channels/components: either one, three, or four main channels. The rest of the channels are optional and can be used to store e.g. alpha for transparency/compositing, depth, or thermal data.
  • There can be multiple frames, with non-zero duration or with zero duration. Frames can be smaller or larger than the image canvas and can be blended in various ways. However, regular video codecs are still preferred for encoding realistic moving content.
  • JPEG XL has built-in support for various color spaces, transfer curves, and high screen brightness. It is specifically designed to seamlessly handle wide color gamut color spaces with high dynamic range such as Rec. 2100 with the PQ or HLG transfer function.
Data structuring:
  • Tiles: Independent coding of sections of a large image by allowing images to be stored in tiles, e.g. for parallelization.
  • Progressive decoding: Mode specifically designed for responsive loading of large images depending on the viewing device's resolution.
Upgrade path:
  • JPEG transcoding: Being a JPEG superset, JXL provides efficient lossless recompression options for images in the traditional/legacy JPEG format that can represent JPEG data in a more space-efficient way and can easily be reversed, e.g. on the fly. Wrapped inside a JPEG XL file/stream, it can be combined with additional elements, e.g. an alpha channel.
  • The format is extensible.
Freedom to use, batteries included:
  • Royalty-free licensing of relevant intellectual property/software patents.
  • Production-ready open-source reference implementation available on GitHub under liberal licensing terms.