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?
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.
This all sounds like standard jpeg compression. Is it just jpeg with extra channels?
Yeah, it compresses better too though, and jpeg XL can be configured to compress lossless, which I imagine would also work here
Lossless JPEG would be amazing.
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.