Didn't Google refuse adding JpegXL because they claimed there wasn't enough interest? I don't think they refused out of security concerns but maybe I'm misremembering that.

You have to adjust the CPU used parameter, not just quality, for AVIF. Though it can indeed be slow it should not be that slow, especially for a 1mp image. The defaults usually use a higher CPU setting for some reason. I have modest infrastructure that generates 2MP AVIF in a hundred ms or so.

According to the chrome platform status page, yes! https://chromestatus.com/feature/5114042131808256

>>>

  - Progressive decoding for improved perceived loading performance
  - Support for wide color gamut, HDR, and high bit depth
  - Animation support

Most of the code in WebP and AVIF is shared with VP8/AV1, which means if your browser supports contemporary video codecs then it also gets pretty good lossy image codecs for free. JPEG-XL is a separate codebase, so it's far more effort to implement and merely providing better compression might not be worth it absent other considerations. The continued widespread use of JPEG is evidence that many web publishers don't care that much about squeezing out a few bytes.

Also from a security perspective the reference implementation of JPEG-XL isn't great. It's over a hundred kLoC of C++, and given the public support for memory safety by both Google and Mozilla it would be extremely embarrassing if a security vulnerability in libjxl lead to a zero-click zero-day in either Chrome or Firefox.

The timing is probably a sign that Chrome considers the Rust implementation of JPEG-XL to be mature enough (or at least heading in that direction) to start kicking the tires.

> various "benchmarks" JpegXL seems just be flat out better than WebP

The decode speed benchmarks are misleading. WebP has been hardware accelerated since 2013 in Android and 2020 in Apple devices. Due to existing hardware capabilities, real users will _always_ experience better performance and battery life with webp.

JXL is more about future-proofing. Bit depth, Wide gamut HDR, Progressive decoding, Animation, Transparency, etc.

JXL does flat out beats AVIF (the image codec, not videos) today. AVIF also pretty much doesn't have hardware decoding in modern phones yet. It makes sense to invest NOW in JXL than on AVIF.

For what people use today - unfortunately there is no significant case to beat WebP with the existing momentum. The size vs perceptive quality tradeoffs are not significantly different. For users, things will get worse (worser decode speeds & battery life due to lack of hardware decode) before it gets better. That can take many years – because hey, more features in JXL also means translating that to hardware die space will take more time. Just the software side of things is only now picking up.

But for what we all need – it's really necessary to start the JXL journey now.

JpegXL and AVIF are comparable formats. Google argued you only needed one, and each additional format is a security vulnerability.

JPEG XL has progressive decoding

https://www.youtube.com/watch?v=UphN1_7nP8U

It was an issue with the main JPEGXL library being unmaintained and possibly open for security flaws. Some people got together and wrote a new one in Rust which then became an acceptable choice for a secure browser.

- avif is better at low bpp (low-quality images), terrible in lossless

- jxl is better at high bpp, best in lossless mode

Google created webp and that is why they are giving it unjustified preferential treatment and has been trying to unreasonably force it down the throat of the internet.