And finally, how much longer will the HTTP "Accepts" header continue to get with these new formats?
<picture>
<source srcset="foo.webp" type="image/webp">
<source srcset="foo.jxr" type="image/vnd.ms-photo">
<img src="foo.jpg" alt="" width="100" height="150">
</picture>
---
About the Accept header, currently they include `image/avif` so I have no reason to believe that `image/jxl` won't be added.
Picture tags should only need two combinations [jpeg xl, jpeg], and [jpeg xl, png]
Yes, absolutely, there is definitely no browser or version of a browser which lacks jxl support and could make use of avif or webp over jpeg.
If, for example, you deal with photos and currently serve AVIF, WebP and JPEG, around 80% of viewers will take AVIF despite the implementations all being under three years old (less than one in Apple-land), and that number will continue to climb, so that the WebP in this chain will be helping practically no one within two years. Moreover, adding WebP is already imposing a tiny cost for every viewer and a likely-noticeable cost for storage and maintenance, while frankly only slightly reducing the cost over JPEG for WebP-but-not-AVIF viewers.
> … qualities above 90. That is likely 30-40 % of all the images in the internet.
I don’t know whether it is, but it shouldn’t be anything like that. For browsing, a JPEG of quality q=90 is ridiculous overkill: that’s the kind of quality you should only get if you’re deliberately downloading high-quality images. A more commonly used figure is q=75, which produces files around 40% of the size of q=90, and most of the time q=60 (around ¼ of the size of q=90) is entirely adequate (perceptually sufficiently indistinct).
I would also expect that such excessive-quality images would be found primarily in systems that don’t support multi-format serving.
however, I believe that web median quality is 85, and 75 is closer to 10 percentile bad quality
The considerable majority of images on the web are way higher-quality than they need to be.