The case against JPEG XL

Lossy compression for web images now offers better efficiency and fidelity than JPEG XL, making it a less compelling choice.

Despite its technical merits, JPEG XL faces significant challenges as a web image codec. While initially praised for its efficiency and versatility, large companies like Google notably rejected it for Chrome in 2023. Recent integration of JPEG XL decoders into Firefox and Chrome has reignited discussions about its adoption, potentially to address security vulnerabilities seen with WebP. However, critical analysis suggests that JPEG XL's lossless compression advantage is marginal, offering only a roughly 11.9% size reduction over lossless WebP on a specific dataset, which is not compelling for the majority of web use cases that prioritize lossy compression. Furthermore, modern encoders for formats like AVIF and SVT-AV1 now outperform JPEG XL in both speed and fidelity per bit, largely due to advanced perceptual tuning and specific coding tools like directional prediction and deblocking filters, which JPEG XL lacks or implements less effectively. These technical disadvantages, combined with slower decode times for features like JPEG recompression, make its widespread web adoption questionable.

The technical analysis highlights that JPEG XL's core strengths—lossless compression and advanced features—are either not compelling enough for the majority of web image needs or are outweighed by modern alternatives. Its lossless efficiency gain is small and tested on an unrepresentative dataset, while its lossy compression performance is now surpassed by highly optimized encoders for formats like AVIF. The absence of critical coding tools such as directional prediction and deblocking filters in JPEG XL's design further hinders its ability to compete with more contemporary codecs that leverage these techniques for superior edge preservation and artifact reduction.

The market appears to be prioritizing codecs that offer a better balance of compression efficiency, speed, and robust implementation for common web use cases. While JPEG XL's flexibility is technically impressive, its practical advantages are diminished by the complexity of its encoding tools and slower decode times for features like JPEG recompression. This suggests that while JPEG XL may find niche applications, its path to becoming a mainstream web standard faces significant technical and performance hurdles compared to established and emerging competitors.