This is a link to a massive study of over 3000 image comparisons between AVIF and JPEG XL.
It’s wayyyy more accurate and comprehensive than anything I could come with testing photos of my own.
The average result is not as dramatic as what I saw with my own image test (but there are some very big differences documented in the dataset).
Not only is AVIF higher image quality at the same file sizes, but decoding speed of AVIF is a pretty consistent 2x or more faster than decoding speed for JPEG XL as well.
A dataset of thousands of tests from a huge research project shows that AVIF is over twice as fast to decode and 25-47% smaller in file size for the same output quality levels (SSIMULACRA2 metric).
If I further filter the results down to the same encoding time as well as the same output image quality, then the results are even more in favor of AVIF: 50-94% smaller file sizes, and 4.7-7.7 times faster to decode.
And, if you increase the “effort” level of the JPEG XL format, trying to compete, it only makes things better for AVIF, and worse for JPEG XL.
With JPEG XL effort level 6, as the baseline, then the results are:
Finally, for what matters most to me, which is pure quality in combination with a given level of efficiency, here is the result for image quality based on 3000 to 5000 comparisons made from the same source images (official CLIC validation data sets) at the same file size (within 5%).
