I'm the author if anyone has questions – AMA

How ergonomic are the modern AVIF encoders? I like libjxl (and cjpegli) because they are really good at generating reasonably compact, high-quality images.

For every other image encoder I used I couldn't find one setting that would make compact, high-quality images across the gamut of inputs (e.g. things like comics that have extremely visible high-frequency content would look terrible at quality settings that looked good for many photographs).

Lossless was discounted due to webp, but doesn't webp lossless only use 8bit depth RGB? (I think it is important to have a separate file extension for lossless stuff anyway, otherwise it gets confusing quickly)

What do you think about the fact that most perceptual quality improvements in SVT-AV1 have been almost only driven by external, non-paid enthusiasts such as yourself while the maintainers have been basically only targeting VoD and RTC?

Compared to JXL (which admittedly has almost nobody working on except veluca these days...) which was focused on it since the beginning, I think it really matters.

We have to apply some weight to the fact that one is open, one isn't, right?

EDIT: Oh! Of course. AVIF is based on AV1. For some reason I was thinking HEIF the entire time I was reading the article. Man... withdrawn!

Really good read, btw. Very good points.

It would be nice to see the actual R-D curves for the codecs instead of compressing them into a single number. Also, what is BD-rate computed with respect to, jpegli at p0?

What do you think the best use cases for jxl are? Where does it still have an advantage over other formats?

I have a lot of basic questions about the CVVDP graph. Is the X axis encoding or decoding speed? Is higher better on the Y axis? What format is Aperture? I assume "aom" is AV1 but it wouldn't hurt to document it.

I would argue that even if JPEG XL isn't the best choice for Web images, if browsers don't support it then that will widely hinder its adoption for its non-Web use cases. Would you agree?

The scenario I'm thinking of is sending a photograph by email. Let's say Sally has just had her second baby, and wants to send baby pictures to her mother, the baby's grandmother. Neither Sally nor her mother are computer professionals, and they don't want to care about image formats. Sally wants to upload a file from her camera, attach it to an email, and send it. Her mother wants to click on the email and see pictures of her new grandchild. Neither one of them wants to have to convert the image themselves.

Let's say it's a few years in the future and Sally's camera produces JPEG XL files by default. (Which I don't think would happen if browsers didn't support it, for exactly the reason I'm about to articulate). If Sally's mother's browser doesn't support displaying JPEG XL, then although Sally (who uses a different browser than her mother) sees the picture in the email when she sends it, her mother writes back an email saying "the picture didn't show up, can you resend it?" And they spend a few back-and-forth emails before finally getting tech support from a friend who helps Sally convert the picture to old-school JPEG so her mother can see it.

If that's the experience for end-users, cameras would hesitate to switch to JPEG XL as a default format. Because nobody wants a hostile review from a user saying "My mother couldn't load my baby pictures, what kind of lousy camera are you making?"

So even if it's not the best format for the Web, I'm still persuaded that having universal browser support for a format intended for photos is an important factor, and devices like cameras will not switch to it as a default format until manufacturers are certain that browser support (and OS support, and electronic photo frame support, and so on) is nearly universal.

None of that takes away from the argument "Other image formats are better for saving space on the Web", which is the main thrust of your post. But I do disagree with the last line, "I'm just not personally convinced we need it in browsers any time soon." I believe that if browser adoption is lacking, adoption of the format in places where it makes lots of sense (like cameras) will also be slow.

What are your thoughts on that argument?

What format would you recommend for archiving photos if I don’t mind slight quality loss?

Very compelling and thoughtfully written article. Thank you!

What about the current AV1 patent issues, like Sisvel/Access Advance and Dolby vs Snap? Does that change the AVIF vs JXL comparison at all?