Originally posted by coder
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FFmpeg Lands JPEG-XL Support
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Originally posted by coder View PostSo, they were ready to break everyone on an older browser or hose the CPU on any client with a lower spec device? Nice.
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Originally posted by coder View PostThanks for the datapoint. Would you tell us more about it? Is it huge in resolution? Does it have large areas with relatively little variation? What was the base JPEG quality level?
FWIW, JPEG and PNG can both do progressive.
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Originally posted by arun54321 View PostThe point of the post is to show jpeg transcode process is lossless.
The reason I asked about file sizes is that, in the event it turns out to be lossless, it would be nice to know how much further compression you're seeing.Last edited by coder; 27 April 2022, 12:07 AM.
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Originally posted by Quackdoc View Postthis is the result of re-encoding a 20-30gb library of photos and anime art. some of the jpeg quality was fine, some was trash, some was encoded with with trash settings some optimized. and of course some were PNGs
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Originally posted by coder View PostThat's interesting, but not as useful as if we knew more about those images. Given their estimate of a 20% size reduction, I'd expect your files are higher-resolution or higher-quality what's needed or justified by their content (i.e. they have comparatively low-entropy). How much detail do they have, at 1:1 scale? Are they a little blurry, when zoomed in that far? Are there large parts of the images with relatively little variation?
Originally posted by coder View PostIf an 82% reduction were typical, you'd think they'd quote that in their "JPEG lossless conversion" FAQ. So, I'm just trying to figure out what makes your case special.
Originally posted by coder View PostThat's cool. Thanks for the datapoint. Doesn't mean it's lossless, though.
For it to be lossless, the decoded JPEG and JPEG-XL version would have to be bit-identical. Please try that, on some of your 82%-reduced files, and let us know.
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Originally posted by coder View PostIt doesn't do that. As I explained, reversible isn't the same as lossless. Lossless would mean the decoded output of .jxl is the same as that of the original .jpg file.
The reason I asked about file sizes is that, in the event it turns out to be lossless, it would be nice to know how much further compression you're seeing.
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Originally posted by LinAGKar View PostIf it's reversible you could convert the JXL back to a JPEG and then decode that to get the same result as decoding the original JPEG.
Originally posted by LinAGKar View PostIt would be really weird if decoding the JXL directly gave a different result.
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Originally posted by coder View PostYou quoted improvements in the range of 5% to 50%. What was the total before/after? From that, we can estimate the average (perhaps a bit skewed by the PNGs).
I can probably just scrape a bunch of sites for jpgs and compress them though, probably wouldn't be hard to do
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