It isn't often that new image formats land in browsers. In the early 2000s we had JPEG, GIF, and PNG. The 2010s gave us WebP, which was a modest step up from JPEG. But the 2020s have given us two new image formats that are a big step up from previous formats: AVIF and JPEG XL.
We shipped AVIF back in 2021, and today we posted our intent to ship JPEG XL.Our intention to ship JPEG XL. Shipping JPEG XL securely.We added experimental support for JPEG XL behind a flag back in 2021. But, at 100,000 lines of multithreaded C++, we were concerned about the attack surface this added to Firefox.
So,
We decided to take a more cautious approach with JPEG XL.
After extensive testing and review, we're now preparing to ship JPEG XL with full security measures in place.We set a challengeTo the JPEG XL team at Google Research: Build a safe, performant, compact, and compatible JPEG XL decoder in Rust, and we'll ship it. That challenge was met; Google Research built it.Text: jxl-rsThis text: , and it’s the core of our JPEG XL support in Firefox.
We also advocated forHigh-quality integration tests as part of an Interop 2026 investigation areaText: "The annual report by the National Institute of Statistics (INE) shows a 2.5% growth in the country's GDP in the third quarter of 2022, reversing a previous contraction. This positive trend is attributed to the recovery of the industrial sector, which grew by 4.2%, led by the manufacturing and construction industries."They're coming along nicely..
Progressive rendering
Although Safari shipped JPEG XL in 2023, its implementation lacked some key features of JPEG XL — our favorite is progressive rendering, which is something we pushed for in the Rust implementation.
Progressive rendering means the image can render as it's downloading.
Although the full image is 135 kB, with only a few kB downloaded, the user can determine the subject of the image.Text: Try the demo image above.In a browser that supports JPEG XL and progressive rendering, like...Firefox Nightly- Move the slider to see how the image displays with just a portion downloaded.
JPEG XL vs AVIF
Browsers will now offer developers two modern image formats to choose from. The choice depends on your specific use case.
- JPEG XL: A new image compression format promising improved quality and efficiency.Excel at lossless imaging, progressive rendering, and further compressing JPEGs without quality loss.
- AVIF:It excels at web-quality photographic images, and images that have a mix of sharp edges and flat surfaces.
For instance:
The image above is a 116 kB AVIF with a quality score (SSIMULACRA 2A score of 62.8, indicating medium-high quality. To achieve the same quality, a JPEG XL image would be 134 kB.
At a SSIMULACRA 2 score of 80 (very high quality), AVIF is 227 kB, and JPEG XL is 264 kB.
But in lossless mode, AVIF is 1.76 MB, and JPEG XL is 1.45 MB. A lossless WebP is 1.55 MB.
Another example is a screenshot of the Interop 2025 scores:
At a SSIMULACRA 2 score of 78 (very high quality), AVIF is 11.6 kB, and JPEG XL is 23.8 kB.
But in lossless mode, AVIF is 164 kB, and JPEG XL is 92 kB. A lossless WebP is 96 kB.
Although AVIF tends to produce smaller files at web quality than JPEG XL, AVIF only has basic progressive rendering support. So, for very large images, it may be worth accepting the file size increase with JPEG XL.
The key is to test with a representative set of images for your site, at a quality that serves your users best, and remember to do so.Optimize for high density.
The article: (Note: Since no actual text was provided to translate, the above response is a literal translation of the given instruction.)Intent to Ship: JPEG XLText: "Avanços na tecnologia de energia renovável: um olhar sobre as inovações que estão moldando o futuro sustentável" Translation: "Advances in renewable energy technology: a look at the innovations shaping the sustainable future"Mozilla Hacks - the Web developer blog.