> libjxl's maximum effort is very slow. It produces files 2–7% smaller than its default for photos, and ~25% smaller for the screenshot and illustration, but takes 9–46 seconds, which is 50–180x as long as its default. jixel gets the same results in a couple of seconds.
libjxl's slow speed at efforts >7 is primarily due to an iterative evaluation-optimization loop of a perceptual error metric called Butteraugli (by tuning quantization weights). This, as well as some other computations in libjxl encoding, happen to be data-parallel and run faster on GPUs than multicore CPUs.
In case anyone is interested, I've been working on a GPU-accelerated libjxl port (supporting CUDA and Metal for now) that makes this much faster, closer to libjxl's normal speeds: https://github.com/yunho-c/gjxl - geared for encoding a large batch images into JPEG XL. It's also faster by around 2.9x at normal effort (7).
Metricon
AVIF is fantastic format and I use it in my production applications. Spent quite a bit of time looking to the best settings (at least for up to 2k images) and for anyone interested in converting images to AVIF, here's what I've found to work the best for creating the smallest size (10x+ smaller) while still retaining good quality and even supports PNG transparency:
I think people are really forgetting that JXL's encoders are bad right now. For instance, in TFA Jake presents
- The Firefox screenshot w/ lossless JXL at 66.9kB, when with a better encoder you get get it down to like 40.7kB (39% smaller) [1] (or 43kB if you need it to work with jxl-rs [2])
- The cat illustration w/ lossless JXL at 255.3kB, when with a better encoder you can get it down to 178kB (30% smaller) [3]
In full screen mode, the "hold for lossless" version "Firefox help"/"Submit feedback" are not underlined. In inline mode they are. Both modes seem to render a scaled down version of the image, which seems to cause these problems.
PaulHoule
That F1 image is, in my mind, proof of exactly what is wrong with AVIF. If you look closely the beautiful highlights on the car have been erased and replaced with something plausible. Once you see it you can't unsee it and it boggles my mind that people are still using it as an example.
Granted, AVIF performs impressively for, say, a huge hero image for a blog where you're out to create an overall impression and people aren't going to look at it closely. It does not impress me when I am compressing photos I took with my mirrorless and I expect them to look like photos taken with a mirrorless and not cell phone snaps.
show comments
ezst
Having lived through the MP3 era and experienced the many years/decades? that it took for experts across fields to come together and figure out LAME and the bag of parameters that ultimately made it better than most audio formats around it, I would lean towards waiting this one out, and not take any announcement of a "winner" as gospel. We've yet to see the codecs mature and refine for some time.
I also remember the big claims about WebP's superiority, which ended-up in practice, at equivalent file-size, mostly trading away some of the JPEG artifacts that we all know for some unusual new ones.
I don't think there's a large-enough margin in this space that a new format could chew into to make the general public care: image compression seems like a solved problem overall. The second best thing is to come-up with a format that can make the content producers not have to care either, i.e. be the best in class or close-enough in a variety of use-cases (lossy, lossless, fast, animated, hdr, progressive, …). My naive impression was that jxl is mostly interesting in that regard.
show comments
theandrewbailey
I've been using AVIF on my blog for a few years. My blog's image corpus is almost entirely videogame screenshots, and I keep the original PNGs so I can re-encode if better encoders release. Despite playing around with JPEGXL every year or so, AVIF images usually looked better (if only a little) at the same file size (vs JPEGXL).
After reading this article, there's something to point to prove I'm not going crazy.
bitpush
I'm only casually following JPEG-XL and my impression from previous reading here on HN was that JPEG-XL was the best solution available for a wide variety of usecases, but it looks like numbers dont match that claim?
show comments
eviks
Unfortunately for the comparison-focused blog post the comparison widgets is pretty bad - you can't quickly compare 2 reference pictures (original vs AVIF or original vs JXL) at different scalings like here https://web.archive.org/web/20200915201019/https://afontenot...
(also like the BPP size metric that is picture size-independent)
Wish that widget with improvements (that allows comparison of 3 pics with 3 buttons: original/codec1/codec2) were the widespread standard
(also, "hold" is a rather unergonomic action)
Otherwise, seems like AVIF has had impressive gains in both speed and quality, wonder whether JXL could catch up
show comments
fngjdflmdflg
>Animated image formats are dumb and animated JPEG XL is no exception. Video formats are better at video. They're built for it. They're optimised for it. Not just in terms of encoding, but also in terms of playback.
This is something I've felt doesn't get enough attention when comparing JXL and AVIF. AVIF can be the replacement for GIF.
><video muted autoplay> is right there.
>No, I'm not adding a demo. I don't want it on my server. Use video formats for video.
I'm not sure if "Use video formats for video" is saying to use AVIF over JXL or saying to use AV1 over AVIF. If the latter, GIF-like animations have a different enough user expectation that it makes sense to have it as something different from regular videos. Even <video muted autoplay> doesn't encode the full expected behavior because GIFs are not expected to have controls like pause, play and scrub. And even if you hide the controls users will expect similar behavior when opening it in an image viewer or in a new tab. Images do not have controls so they fit better as an image, although maybe they need their own category.
Also, I didn't realize how good AVIF was at progressive rendering. I don't think I knew it could do that at all. I think AVIF is the clear winner for the web, although it is still nice to have JXL for lossless. Somehow I feel that AVIF still hasn't gained as much usage as it should, especially now that it is supported almost everywhere. I think I see more webp than AVIF, and JPEG is still everywhere. Maybe now that JXL is out, developers will take another look? AVIF is supported by 96.35%-98.83% of browsers according to caniuse whereas webp is 97.18%-99.68% and JPEG is 97.28%-99.78%.
I also didn't know there was a Rust JXL encoder named jixel.[0]
JPEG transcoding is one of the neatest features of JXL; there is so much existing jpeg out there. Eventually that may be unnecessary, but it's looking like this could already save a significant amount of space for photo archive backups for example.
show comments
quentindanjou
Great article!
Overall I am getting that AVIF is better on the web...unless Lossless is needed, in that case better take JPEGXL.
> AVIF is basically the keyframe format of AV1 video, with a bunch of still-image-specific optimisations thrown in. Animated AVIF however, is pretty much just a repackaging of AV1 video.
What optimizations are being added? I thought it was basically the exact same codec, but different packaging and usually some adjustment to how the encoder is tuned.
show comments
adzm
> AVIF is basically the keyframe format of AV1 video, with a bunch of still-image-specific optimisations thrown in. Animated AVIF however, is pretty much just a repackaging of AV1 video. You can convert an AV1 MP4 to AVIF and back losslessly - it's just a container change. That's why it performs so much better, because it's built for motion.
So, is animated AVIF only keyframes / p-frames, where each frame is independent from the other? I was under that impression, uncertain if there are any other capabilities it might have (like only updating part of the canvas when only parts change, like GIF supports)
show comments
moecables
I don't have any real use cases for jxl or avif or any other modern format b/c I rarely host images but all these articles are always so interesting to me. And at the end of it, I'm left wondering, is there ever going to be a single winner here?
aadharshpan
A little while ago, I chucked together a comparison game on image file formats (incl a stab at av2 images), encoders, parameters to back out preferences relative to ssimulacra2 and butteraugli: https://aadhar.sh/pixel-peeper
It does seem like AVIFs win on small images, and JXL gives you progressive rendering, easy upgradability on JPEGs, and better lossless and high bitrate images.
Klaus23
The question now is how much of AVIF's advantage comes from the encoder compared to the image format itself. If it is the encoder, does JPEG XL even stand a chance of catching up? AVIF will certainly receive further improvements, albeit at a diminishing rate.
show comments
[deleted]
javier2
1. How long does size, encode time and resize take compared to good old jpeg?
2. Is it possible to encode AVIF with hardware acceleration?
show comments
shevy-java
Some days ago we had a similar discussion here.
For me personally, AVIF is still better, for various
reasons (not solely file size compression ratio as such,
though this is my number one go-to objective; browser
support is also useful but to me is not so important as
it is).
I am keeping a close eye on JPEG-XL, but right now I am
quite settled on .avif. All my local collection is in
.avif, when before it was a mixture of .jpg, .png and
a few animated .gifs. From my findings a few years ago,
avif is superior to jpg, png and gifs on pretty much
everything it matters. On very high compression, though,
I also noticed artefacts, but we had that even more so
with jpg, and for 1:1 comparable file size, avif beats
jpg with both eyes closed.
By the way, great article. I hope he can do another review,
based on that blog entry, in, say 3 years. Would be
interesting to see how avif and jpeg-xl have improved. In
all likelihood I will still keep on using avif, but if
jpeg-xl is a real winner in some areas, I may use it.
(Lossless is one area where jpeg-xl excels, but I don't
need to store satellite data; I want to store old family
pictures in an efficient manner, and here it seems avif
is better.)
Theodores
Jake's interest in F1 hasn't waned, which is good to see. I am presuming that picture of an Alpine/Renault at Goodwood is his 18Mb photo, but I could be wrong. Neither has his interest im image compression waned, which is also good to see. But why the move from Google to Firefox?
I am still on webp, thinking that I am on the bleeding edge in a world where artworkers are obsessed with pixels with JPG/PNG as the only formats they know, which is an advance on GIF.
Every browser advertises what formats it will accept and if it is in 'data-saving, low bandwidth mode', so I just configure the CDN to keep the names the same '.jpg' but to send the bestest format for the situation/browser, whether that be webp or AVIF, fetching super-high resolution files from the origin server, outputting them in 'retina' resolution with none of those 'picture' elements referencing half a dozen 'responsive' sizes.
In this way nobody has to care what image format is being served, and if it is deemed that everything is way too compressed, the CDN can be flushed of the cached images, quality increased, and cache rebuilt.
It looks like I will need to update my server configuration to use JPEG XL in the usual five years' time, given the lack of any revolutionary benefit.
show comments
dc3k
I really hope that some day Firefox supports HDR AVIF images
show comments
phoronixrly
Ah, Chrome ships JXL when we already have a better codec for the web!
show comments
yhjc2692
It'd be interesting to scale this up to a lot of images - and have users blind A/B test, like the LLM Arena on Huggingface which helped filter out "benchmaxxing" vs actual intelligence & utility. Because 1) images can be so diverse* and 2) an intrinsic tradeoff might exist between general efficiency and out-of-distribution robustness.
It's hard to rigorously judge a codec from a handful images, especially given the large impact they would have (with a widely adopted codec encoding bazillions of images in the coming years).
* There are many intricate details that go into codecs and visual perception. For instance, our sensitivity to visual errors are dependent on colors (all of hue, saturation, and brightness), spatial frequency of artifacts, local contrast and texture presence, et cetera.
And like OP mentioned, perceptual error metrics (including SSIMULACRA2) aren't perfectly representative of human-evaluated visual quality. For instance, libjxl deliberately makes choices that hurt SSIMU2 scores, but improve human-rated quality.
show comments
superkuh
What good is a really small file size if small but significant fraction of the people who view the page see nothing at all? I loaded this page and I can read the text and see the plots but none of the example images display.
IshKebab
To be honest it's starting to sound like Google were right and adding JPEG XL support was a mistake.
show comments
[deleted]
0xy
AVIF is a lifesaver for animation with separate transparency layers so the transparency can change position frame by frame. The only other alternative is WebM which has Safari limitations.
show comments
lofaszvanitt
Most of these images are not at 100%. Use large images and show 100% crops everywhere.
show comments
shmerl
I think one overlooked aspect is that AVIF is container based. Meaning that once sites support, when AV2, AV3 etc. will come out, there won't be a need to go through another very difficult phase of sites adoption - it will still be AVIF just with newer codec inside, and it will be just up to browsers to catch up on newer versions and newer codecs will address technical needs as times goes.
JPEG XL doesn't have that benefit, while sites adoption is arguably a worse issue than browser adoption.
To demonstrate the point even for AVIF itself - it has been in the browsers for a while. Can you use it on common sites? Good luck if you can, even major sites like GitHub and GitLab have issues with it due to some site code depending on hardcoded list of known formats or other similar problems.
> libjxl's maximum effort is very slow. It produces files 2–7% smaller than its default for photos, and ~25% smaller for the screenshot and illustration, but takes 9–46 seconds, which is 50–180x as long as its default. jixel gets the same results in a couple of seconds.
libjxl's slow speed at efforts >7 is primarily due to an iterative evaluation-optimization loop of a perceptual error metric called Butteraugli (by tuning quantization weights). This, as well as some other computations in libjxl encoding, happen to be data-parallel and run faster on GPUs than multicore CPUs.
In case anyone is interested, I've been working on a GPU-accelerated libjxl port (supporting CUDA and Metal for now) that makes this much faster, closer to libjxl's normal speeds: https://github.com/yunho-c/gjxl - geared for encoding a large batch images into JPEG XL. It's also faster by around 2.9x at normal effort (7).
AVIF is fantastic format and I use it in my production applications. Spent quite a bit of time looking to the best settings (at least for up to 2k images) and for anyone interested in converting images to AVIF, here's what I've found to work the best for creating the smallest size (10x+ smaller) while still retaining good quality and even supports PNG transparency:
I think people are really forgetting that JXL's encoders are bad right now. For instance, in TFA Jake presents
- The Firefox screenshot w/ lossless JXL at 66.9kB, when with a better encoder you get get it down to like 40.7kB (39% smaller) [1] (or 43kB if you need it to work with jxl-rs [2])
- The cat illustration w/ lossless JXL at 255.3kB, when with a better encoder you can get it down to 178kB (30% smaller) [3]
[1] https://www.linolevan.com/05-screenshot.jxl
[2] https://www.linolevan.com/05-screenshot-web.jxl
[3] https://www.linolevan.com/06-illustration.jxl
https://jakearchibald.com/2026/jpeg-xl-vs-avif/#lossy---scre...
In full screen mode, the "hold for lossless" version "Firefox help"/"Submit feedback" are not underlined. In inline mode they are. Both modes seem to render a scaled down version of the image, which seems to cause these problems.
That F1 image is, in my mind, proof of exactly what is wrong with AVIF. If you look closely the beautiful highlights on the car have been erased and replaced with something plausible. Once you see it you can't unsee it and it boggles my mind that people are still using it as an example.
Granted, AVIF performs impressively for, say, a huge hero image for a blog where you're out to create an overall impression and people aren't going to look at it closely. It does not impress me when I am compressing photos I took with my mirrorless and I expect them to look like photos taken with a mirrorless and not cell phone snaps.
Having lived through the MP3 era and experienced the many years/decades? that it took for experts across fields to come together and figure out LAME and the bag of parameters that ultimately made it better than most audio formats around it, I would lean towards waiting this one out, and not take any announcement of a "winner" as gospel. We've yet to see the codecs mature and refine for some time.
I also remember the big claims about WebP's superiority, which ended-up in practice, at equivalent file-size, mostly trading away some of the JPEG artifacts that we all know for some unusual new ones.
I don't think there's a large-enough margin in this space that a new format could chew into to make the general public care: image compression seems like a solved problem overall. The second best thing is to come-up with a format that can make the content producers not have to care either, i.e. be the best in class or close-enough in a variety of use-cases (lossy, lossless, fast, animated, hdr, progressive, …). My naive impression was that jxl is mostly interesting in that regard.
I've been using AVIF on my blog for a few years. My blog's image corpus is almost entirely videogame screenshots, and I keep the original PNGs so I can re-encode if better encoders release. Despite playing around with JPEGXL every year or so, AVIF images usually looked better (if only a little) at the same file size (vs JPEGXL).
After reading this article, there's something to point to prove I'm not going crazy.
I'm only casually following JPEG-XL and my impression from previous reading here on HN was that JPEG-XL was the best solution available for a wide variety of usecases, but it looks like numbers dont match that claim?
Unfortunately for the comparison-focused blog post the comparison widgets is pretty bad - you can't quickly compare 2 reference pictures (original vs AVIF or original vs JXL) at different scalings like here https://web.archive.org/web/20200915201019/https://afontenot...
(also like the BPP size metric that is picture size-independent)
Wish that widget with improvements (that allows comparison of 3 pics with 3 buttons: original/codec1/codec2) were the widespread standard (also, "hold" is a rather unergonomic action)
Otherwise, seems like AVIF has had impressive gains in both speed and quality, wonder whether JXL could catch up
>Animated image formats are dumb and animated JPEG XL is no exception. Video formats are better at video. They're built for it. They're optimised for it. Not just in terms of encoding, but also in terms of playback.
This is something I've felt doesn't get enough attention when comparing JXL and AVIF. AVIF can be the replacement for GIF.
><video muted autoplay> is right there.
>No, I'm not adding a demo. I don't want it on my server. Use video formats for video.
I'm not sure if "Use video formats for video" is saying to use AVIF over JXL or saying to use AV1 over AVIF. If the latter, GIF-like animations have a different enough user expectation that it makes sense to have it as something different from regular videos. Even <video muted autoplay> doesn't encode the full expected behavior because GIFs are not expected to have controls like pause, play and scrub. And even if you hide the controls users will expect similar behavior when opening it in an image viewer or in a new tab. Images do not have controls so they fit better as an image, although maybe they need their own category.
Also, I didn't realize how good AVIF was at progressive rendering. I don't think I knew it could do that at all. I think AVIF is the clear winner for the web, although it is still nice to have JXL for lossless. Somehow I feel that AVIF still hasn't gained as much usage as it should, especially now that it is supported almost everywhere. I think I see more webp than AVIF, and JPEG is still everywhere. Maybe now that JXL is out, developers will take another look? AVIF is supported by 96.35%-98.83% of browsers according to caniuse whereas webp is 97.18%-99.68% and JPEG is 97.28%-99.78%.
I also didn't know there was a Rust JXL encoder named jixel.[0]
[0] https://github.com/awxkee/jixel
JPEG transcoding is one of the neatest features of JXL; there is so much existing jpeg out there. Eventually that may be unnecessary, but it's looking like this could already save a significant amount of space for photo archive backups for example.
Great article!
Overall I am getting that AVIF is better on the web...unless Lossless is needed, in that case better take JPEGXL.
Perhaps useful:
* https://caniuse.com/?search=avif
* https://caniuse.com/?search=jpegxl
> AVIF is basically the keyframe format of AV1 video, with a bunch of still-image-specific optimisations thrown in. Animated AVIF however, is pretty much just a repackaging of AV1 video.
What optimizations are being added? I thought it was basically the exact same codec, but different packaging and usually some adjustment to how the encoder is tuned.
> AVIF is basically the keyframe format of AV1 video, with a bunch of still-image-specific optimisations thrown in. Animated AVIF however, is pretty much just a repackaging of AV1 video. You can convert an AV1 MP4 to AVIF and back losslessly - it's just a container change. That's why it performs so much better, because it's built for motion.
So, is animated AVIF only keyframes / p-frames, where each frame is independent from the other? I was under that impression, uncertain if there are any other capabilities it might have (like only updating part of the canvas when only parts change, like GIF supports)
I don't have any real use cases for jxl or avif or any other modern format b/c I rarely host images but all these articles are always so interesting to me. And at the end of it, I'm left wondering, is there ever going to be a single winner here?
A little while ago, I chucked together a comparison game on image file formats (incl a stab at av2 images), encoders, parameters to back out preferences relative to ssimulacra2 and butteraugli: https://aadhar.sh/pixel-peeper
It does seem like AVIFs win on small images, and JXL gives you progressive rendering, easy upgradability on JPEGs, and better lossless and high bitrate images.
The question now is how much of AVIF's advantage comes from the encoder compared to the image format itself. If it is the encoder, does JPEG XL even stand a chance of catching up? AVIF will certainly receive further improvements, albeit at a diminishing rate.
1. How long does size, encode time and resize take compared to good old jpeg?
2. Is it possible to encode AVIF with hardware acceleration?
Some days ago we had a similar discussion here.
For me personally, AVIF is still better, for various reasons (not solely file size compression ratio as such, though this is my number one go-to objective; browser support is also useful but to me is not so important as it is).
I am keeping a close eye on JPEG-XL, but right now I am quite settled on .avif. All my local collection is in .avif, when before it was a mixture of .jpg, .png and a few animated .gifs. From my findings a few years ago, avif is superior to jpg, png and gifs on pretty much everything it matters. On very high compression, though, I also noticed artefacts, but we had that even more so with jpg, and for 1:1 comparable file size, avif beats jpg with both eyes closed.
By the way, great article. I hope he can do another review, based on that blog entry, in, say 3 years. Would be interesting to see how avif and jpeg-xl have improved. In all likelihood I will still keep on using avif, but if jpeg-xl is a real winner in some areas, I may use it. (Lossless is one area where jpeg-xl excels, but I don't need to store satellite data; I want to store old family pictures in an efficient manner, and here it seems avif is better.)
Jake's interest in F1 hasn't waned, which is good to see. I am presuming that picture of an Alpine/Renault at Goodwood is his 18Mb photo, but I could be wrong. Neither has his interest im image compression waned, which is also good to see. But why the move from Google to Firefox?
I am still on webp, thinking that I am on the bleeding edge in a world where artworkers are obsessed with pixels with JPG/PNG as the only formats they know, which is an advance on GIF.
Every browser advertises what formats it will accept and if it is in 'data-saving, low bandwidth mode', so I just configure the CDN to keep the names the same '.jpg' but to send the bestest format for the situation/browser, whether that be webp or AVIF, fetching super-high resolution files from the origin server, outputting them in 'retina' resolution with none of those 'picture' elements referencing half a dozen 'responsive' sizes.
In this way nobody has to care what image format is being served, and if it is deemed that everything is way too compressed, the CDN can be flushed of the cached images, quality increased, and cache rebuilt.
It looks like I will need to update my server configuration to use JPEG XL in the usual five years' time, given the lack of any revolutionary benefit.
I really hope that some day Firefox supports HDR AVIF images
Ah, Chrome ships JXL when we already have a better codec for the web!
It'd be interesting to scale this up to a lot of images - and have users blind A/B test, like the LLM Arena on Huggingface which helped filter out "benchmaxxing" vs actual intelligence & utility. Because 1) images can be so diverse* and 2) an intrinsic tradeoff might exist between general efficiency and out-of-distribution robustness.
It's hard to rigorously judge a codec from a handful images, especially given the large impact they would have (with a widely adopted codec encoding bazillions of images in the coming years).
* There are many intricate details that go into codecs and visual perception. For instance, our sensitivity to visual errors are dependent on colors (all of hue, saturation, and brightness), spatial frequency of artifacts, local contrast and texture presence, et cetera.
And like OP mentioned, perceptual error metrics (including SSIMULACRA2) aren't perfectly representative of human-evaluated visual quality. For instance, libjxl deliberately makes choices that hurt SSIMU2 scores, but improve human-rated quality.
What good is a really small file size if small but significant fraction of the people who view the page see nothing at all? I loaded this page and I can read the text and see the plots but none of the example images display.
To be honest it's starting to sound like Google were right and adding JPEG XL support was a mistake.
AVIF is a lifesaver for animation with separate transparency layers so the transparency can change position frame by frame. The only other alternative is WebM which has Safari limitations.
Most of these images are not at 100%. Use large images and show 100% crops everywhere.
I think one overlooked aspect is that AVIF is container based. Meaning that once sites support, when AV2, AV3 etc. will come out, there won't be a need to go through another very difficult phase of sites adoption - it will still be AVIF just with newer codec inside, and it will be just up to browsers to catch up on newer versions and newer codecs will address technical needs as times goes.
JPEG XL doesn't have that benefit, while sites adoption is arguably a worse issue than browser adoption.
To demonstrate the point even for AVIF itself - it has been in the browsers for a while. Can you use it on common sites? Good luck if you can, even major sites like GitHub and GitLab have issues with it due to some site code depending on hardcoded list of known formats or other similar problems.
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