I've been hearing about fights over JpegXL and WebP (and AVIF?) for years, but don't know much about it.

From a quick look at various "benchmarks" JpegXL seems just be flat out better than WebP in both compression speed and size, why has there been such reluctance from Chromium to adopt it? Are there WebP benefits I'm missing?

My only experience with WebP has been downloading what is nominally a `.png` file but then being told "WebP is not supported" by some software when I try to open it.

1 black pixel of .webp is smaller than 1 black pixel of .jpegxl that is also smaller than 1 black pixel of .png

so webp > jpegxl > png

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.

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

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

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

> 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.

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.

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.