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Comment by gbanfalvi | Hacker News Reader

And how does it compare against HEIF?

Not comparable. Brunsli and Lepton are lossless compressors for JPEG files; HEIF is a completely different lossy image encoder.

To compare the size of a Brunsli/Lepton encoded JPEG file with an HEIF image, you'd need to define some sort of quality equivalence between the two, which gets complicated fast.

HEIF can't compress JPEG images losslessly

Indeed, HEIF/HEIC is basically a slightly dumbed down HEVC (h.265) i-frame (full frame) (HEIC)[1] and new container format (HEIF)[2], similar to WEBP being VP8 i-frames in a RIFF container. So they are used as full blown codecs in practice, usually not in a lossless mode, so shifting JPEG to HEIC or WEBP will lose some quality.

[1] Decoding HEIC in Windows (10) requires you to have installed a compatible HEVC decoder. Which is 99 cents (and the hassle of setting up a store accounts and payment processing with MS) or an alternative free one which will use the HEVC codec that is shipped with hardware such as newer Intels (QSV) or GPUs. Thank you patent mess!

[2] HEIF the container format can contain JPEG data, but in practice does not or only as a supplementary image (previews, pre-renders, thumbnails, etc)

Below 0.5 bpp, both HEIF or BPG [1] and AVIF performs quite a bit better than JPEG XL , XL shines in 0.8 bpp. At least in initial testing.

[1] https://bellard.org/bpg/

Do you have a link for JPEG XL comparisons ? The comparisons on that page are with JPEG XR, which is a different thing.

Unfortunately It couldn't find the exact one, it was from the author's presentation against a few other codec on common metrics such as PSNR and SSIM.

There is a thread on Doom9 [1] with similar results though.

[1] https://forum.doom9.org/showpost.php?p=1894341&postcount=167

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