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submitted 4 months ago by cm0002@lemmy.world to c/technology@lemmy.world
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[-] AbouBenAdhem@lemmy.world 47 points 4 months ago

Spectral JPEG XL utilizes a technique used with human-visible images, a math trick called a discrete cosine transform (DCT), to make these massive files smaller [...] it then applies a weighting step, dividing higher-frequency spectral coefficients by the overall brightness (the DC component), allowing less important data to be compressed more aggressively.

This all sounds like standard jpeg compression. Is it just jpeg with extra channels?

[-] Prok@lemmy.world 36 points 4 months ago

Yeah, it compresses better too though, and jpeg XL can be configured to compress lossless, which I imagine would also work here

[-] dohpaz42@lemmy.world 8 points 4 months ago

Lossless JPEG would be amazing.

[-] zerofk@lemm.ee 7 points 4 months ago

JPEG 2000 supports lossless mode.

[-] Cocodapuf@lemmy.world 3 points 4 months ago

In my experience, as you increase the quality level of a jpeg, the compression level drops significantly, much more than with some other formats, notably PNG. I'd be curious to see comparisons with png and gif. I wouldn't be surprised if the new jpeg compresses better at some resolutions, but not all, or with only some kind of images.

[-] rice@lemmy.org 7 points 4 months ago

jpeg xl has been in development from FLIF for like 15 years there are tons of comparisons all over, even live ones on youtube

[-] uis@lemm.ee 2 points 4 months ago
[-] zerofk@lemm.ee 5 points 4 months ago

Kind of, but JPEG converts image data to its own internal 3 came channel colour space before applying DCT. It is not compressing the R, G and B channels of most images. So a multichannel compression is not just compressing each channel separately.

[-] AbouBenAdhem@lemmy.world 1 points 4 months ago

Yeah, jpeg converts to lab (or something similar, I think). But the dimensions are the same: one channel for lightness, and then a number of channels one less than the total number of sampled frequencies to capture the rest of the color space.

this post was submitted on 29 Mar 2025
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