Firefox Announces Intent to Ship JPEG XL Image Format Support

Browser Support for JPEG XL

Firefox has declared its intent to integrate JPEG XL, a modern image format, into its browser. This follows a similar announcement from Chrome and existing partial support in Safari, indicating that JPEG XL will achieve broad browser compatibility by the end of the year. This marks a significant update in web image formats, providing developers with more choices beyond established options like JPEG, GIF, PNG, and WebP.

Secure Implementation in Firefox

Initially, Firefox had experimental JPEG XL support behind a flag since 2021. Concerns regarding the security implications of integrating a large C++ codebase led Firefox to challenge Google Research to develop a secure, performant, and compact JPEG XL decoder in Rust. Google Research responded by creating `jxl-rs`, which now forms the core of Firefox's JPEG XL implementation, addressing the security and performance requirements.

Progressive Rendering Feature

A key feature of JPEG XL, progressive rendering, allows images to display gradually as they download. While Safari's 2023 implementation of JPEG XL lacked this capability, Firefox pushed for its inclusion in the Rust-based decoder. This feature improves user experience by enabling users to discern image content quickly, even with only a small portion of the data downloaded.

JPEG XL vs. AVIF Comparison

With the advent of JPEG XL, web developers now have two modern image formats, JPEG XL and AVIF, to choose from. JPEG XL excels in lossless imagery, progressive rendering, and recompressing JPEGs without quality loss. AVIF is optimized for web-quality photographic images and those with a mix of sharp edges and flat surfaces. For example, in lossless scenarios, JPEG XL can be more efficient than AVIF and WebP, while AVIF might offer smaller file sizes for certain quality levels of photographic images.