jpegxl.info
JPEG XL and image compression in general, socialism/marxism/trotskyism, miscellaneous geekery.
31 posts
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31 following
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Currently at the 107th JPEG meeting but next week or so we can catch up if you'd like!
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Development started already in 2018, the core codestream syntax was more or less finalized at the end of 2020, the file format a bit later, and the first edition of the standard was published in the beginning of 2022. Usually that's considered the official birth year.
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JPEG is 33 years old.
JPEG 2000 is 25 years old.
JPEG XR is 15 years old (or almost 20 years since it is basically identical to Windows Media Photo, .wdp).
JPEG XL is 3 years old.
In terms of compression and functionality, jxl can do basically everything that jpeg, j2k and jxr can do, or more.
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Lossless JXL can do anything PNG can do (and more), with better compression.
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For low-color images, there is certainly room for 'porting' some lossless webp tricks to libjxl, like doing better palette ordering and making better use of lz77. As a format, jxl should be more expressive and versatile. In particular for HDR.
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identify -verbose will have that information...
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Maybe "compacted colors" could work as a term, assuming you're squeezing a broader spectrum into the visible range. Basically the actual 'colors' are even more 'vibrant' but human eyes just cannot detect most of them, so it's a kind of desaturation / gamut mapping really.
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Of course, the RGB+residuals would still allow reconstructing the whole spectrum, it just would be a way to have a nicer preview than only something grayscale.
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Instead of doing a DCT on the whole spectrum, perhaps some variant transform could be used that produces R,G,B values (that more or less correspond to L,M,S cone responses) + a bunch of residuals? Maybe some kind of multi-channel generalization of YCoCg to make it work for both lossless and lossy...
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Everything related to JPEG XL, basically:
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IIRC, ImageMagick has some weird convention that quality 0 means "default quality" instead of very low quality.
In recent libjxl versions, you can use
JxlEncoderDistanceFromQuality() to do the mapping, maybe IM should switch to that to make sure it uses the same mapping as cjxl.
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It is autocomplete on steroids, with a way more sophisticated statistical model than just n-grams or something simple like that. But in the end it still only produces a plausible continuation of language tokens based on its training set.
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In my head, I always replace "ChatGPT" with "autocomplete 2.0", which is basically what it is. It helps to keep in mind exactly how error-prone it still is, even if it has become amazingly good at keeping up appearances.
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Yes, you can make an animated jxl this way. The Thorium browser will play those just fine, for example.
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Yes, but I cannot promise it is unbiased :)
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Belgium.