Comment by bmacho

3 years ago

How is lossless webp 0.6th of the size of lossless avif? I find it hard to believe that.

WebP is awesome at lossless and way better than even PNG.

It's because WebP has a special encoding pipeline for lossless pictures (just like PNG) while AVIF is basically just asking a lossy encoder originally designed for video content to stop losing detail. Since it's not designed for that it's terrible for the job, taking lots of time and resources to produce a worse result.

  • On the other hand, animated webp is surprisingly bad considering that the format comes from a video codec.

  • > and way better than even PNG.

    I mean it's kinda hard to be worse than just shoving a bitmap through zlib...

Lossless webp is actually quite good, especially on text heavy images, e.g. screenshots of a terminal with `cwebp -z9` are usually smaller than `jxl -d 0 -e 9` in my experience.

Lossless AVIF is just really quite bad. Notice that how for photographic content, it is barely better than PNG, and for non-photographic content, it is far worse than PNG.

  • It's so bad you wonder why AV1 even has a lossless mode. Maybe lossy mode has some subimages it uses lossless mode on?

    • It has lossless just to check a box in terms of supported features. A bit like how JPEG XL supports animation just to have feature parity. But in most cases, you'll be better off using a video codec for animation, and an image format for images.

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