• AbouBenAdhem@lemmy.world
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    3 days 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
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      3 days ago

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

        • Cocodapuf@lemmy.world
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          3 days 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.

    • wischi@programming.dev
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      3 days ago

      It’s not just like jpeg with extra channels. It’s technically far superior, supports loss less compression, and the way the decompression works would make thumbnails obsolete. It can even recompress already existing JPEGs even smaller without additional generation loss. It’s hard to describe what a major step this format would be without getting very technical. A lot of operating systems and software already support it, but the Google chrome team is practically preventing widespread adoption because of company politics.

      https://issues.chromium.org/issues/40168998

        • wischi@programming.dev
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          2 days ago

          JPEG does not support lossless compression. There was an extension to the standard in 1993 but most de/encoders don’t implement that and it never took off. With JPEG XL you get more bang for your buck and the same visual quality will get you a smaller file. There would be no more need for thumbnails because of improved progressive decoding.

          https://youtu.be/UphN1_7nP8U

          • uis@lemm.ee
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            1 day ago

            Then same can be said about JPEG LS and JPEG XL. Most browsers don’t implement that.

        • wischi@programming.dev
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          2 days ago

          JPEG does not support lossless compression. There was an extension to the standard in 1993 but most de/encoders don’t implement that and it never took off. With JPEG XL you get more bang for your buck and the same visual quality will get you a smaller file. There would be no more need for thumbnails because of improved progressive decoding.

          https://youtu.be/UphN1_7nP8U

    • zerofk@lemm.ee
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      3 days 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
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        3 days 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.