libjxl VS jxl.js

> Regarding JPEG XL's mobile support, it makes sense it would see limited development if the company that manages one of the biggest mobile players has been the greatest restriction on their success. The lack of support also disincentivises manufacturers to prioritise support.

There was literally no involvement from any hardware vendor in the standardization of JPEG XL. It went from a Call for Proposals in Sept 2018 to Committee Draft in Aug 2019 with very little time for industry feedback. Contrast this with AV1 which had involvement from hardware vendors Intel, NVIDIA, Arm, AMD, Broadcom, Amlogic from the beginning as well as companies who ship media on hardware at scale such as Cisco, Netflix, Samsung and yes Google. These companies reviewed and provided significant feedback on the format that made it suitable for hardware implementation.

https://news.ycombinator.com/threads?id=JyrkiAlakuijala is a lead on the project and a Google employee, and active in JPEG XL development https://github.com/libjxl/libjxl/commits?author=jyrkialakuij...

https://github.com/libjxl/libjxl/blob/main/doc/format_overvi... is a pretty detailed but good overview. The highlights are variable size DCT (up to 128x128), ANS entropy prediction, and chroma from luminance prediction. https://github.com/libjxl/libjxl/blob/main/doc/encode_effort... also gives a good breakdown of features by effort level.

For JPEG XL, refer to its format overview [1]. In short its lossless mode uses a combination of multiple techniques: the rANS coding with an alias table, LZ77, reversible color transforms, a general vector quantization that subsumes palettes, a modified Haar transform and a learnable meta-adaptive decision tree for context modelling.

One good thing about JPEG XL is that its lossy mode also largely uses the same tool, with a major addition of specialized quantization and context modelling for low- and high-frequenty components.

[1] https://github.com/libjxl/libjxl/blob/main/doc/format_overvi...

The cjxl source is here. If you spot any reason why -x strip=exif may not work, tell me.

The problem is that the instructions for actually running the WASM file are not that clear... the docs the author mentions shows how to compile to WASM, which is easy enough, but then here's the instructions to make that actually work in the browser:

https://github.com/libjxl/libjxl/blob/main/tools/wasm_demo/R...

Yeah, you need some mysterious Python script, a JS service worker at runtime, choose whether you want the WASM or WASM_SIMD target, use a browser that supports Threads and SIMD if you chose that, make sure to serve everything with the appropriate custom HTTP headers... just reading that, I can see that to get this stuff working on non-browser WASM targets would likely require expertise in WASM, which is the point of the OP. WASM's UX is just not there yet.

https://github.com/libjxl/libjxl#usage

> Specifically for JPEG files, the default cjxl behavior is to apply lossless recompression and the default djxl behavior is to reconstruct the original JPEG file (when the extension of the output file is .jpg).

I mean compiling a bleeding edge kicad, inkscape or jpeg-xl is easy. But will probably trash your system if you already have an older version installed.

But you look at your image viewer that could have the lossless indicator? (and there is an issue open to add this indicator to the jxl files)

https://github.com/libjxl/libjxl/issues/432

> It's so frustrating how the chromium team is ending up as a gatekeeper of the Internet by pick and choosing what gets developed or not.

https://github.com/niutech/jxl.js is based on Chromium tech (Squoosh from GoogleChromeLabs) and provides an opportunity to use JXL with no practical way for Chromium folks to intervene.

Even if that's a suboptimal solution, JXL's benefits supposedly should outweight the cost of integrating that, and yet I haven't seen actual JXL users running to that in droves.

So JXL might not be a good support for your theory: where people could do they still don't. Maybe the format isn't actually that important, it's just a popular meme to rehash.

https://github.com/niutech/jxl.js a javascript polyfill taken from the main page https://jpegxl.info/

There are other decoders [0] written in a "safe language" (rust) listed as well. So no there are many "safe" implementations

[0] https://github.com/tirr-c/jxl-oxide

> If you care about JXL, and only want to support JXL, and you put a JXL in your picture tag, then the browser still won't render it, even if you use a picture tag.

Is this true if you provide a polyfill? Have you tried it and it failed? (Serious question.)

https://github.com/niutech/jxl.js

All of the people here who are so passionate about JPEG-XL will be happy to learn that there's nothing preventing them from using it on their sites right now:

https://github.com/niutech/jxl.js

If you want Chrome to ship with JPEG-XL support, use it. At some point, browser makers will decide it's worth the cost to them and all users to add it.

> Please be aware that some images may not load on this page unless your browser supports JPEG-XL

The site could provide a WebAssembly decoder to make the JPEG-XL images work for everyone.

For example, here's a WebAssembly decoder: https://github.com/niutech/jxl.js

Demo: https://niutech.github.io/jxl.js/

at this point, I'd consider just using a polyfill library to decode jpegxl data client-side, like JXL https://github.com/niutech/jxl.js

:) There are some wasm vs native benchmarks in the context of JPEG XL (for example https://github.com/niutech/jxl.js#benchmark)

For adding JPEG XL support I went with jxl.js which I modified for my use case. After looking through the main file, which is also called jxl.js, I decided I only needed 2 relevant code blocks. The one to decode the image and the one to turn the ImageData into something I could display in my existing codebase (which I already partially had implemented for another use case).

It's easy - you'll get ReferenceError: SharedArrayBuffer is not defined when the COOP and COEP headers are not set. Multithreading is enabled by default if you use the scripts from multithread folder. If only SIMD is supported, it is being used. Oh, and progressive decoding is also enabled by default.