4 ms·

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

• 149765 3y ago
  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.
• lonjil 3y ago
  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.
  • edflsafoiewq 3y ago
    It's so bad you wonder why AV1 even has a lossless mode. Maybe lossy mode has some subimages it uses lossless mode on?
    • jonsneyers 3y ago
      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.
      • samatman 3y ago
        There are some user-level differences between an animated image and a video, which haven't really been satisfactorily resolved since the abandonment of GIF-the-format. An animated image should pause when clicked, and start again on another click, with setting separate from video autoplay to control the default. It should not have visible controls of any sort, that's the whole interface. It should save and display on the computer/filesystem as an image, and degrade to the display frame when sent along a channel which supports images but not animated ones. It doesn't need sound, or CC, or subtitles. I should be able to add it to the photo roll on my phone if I want. There are a lot of little considerations like this, and it would be well if the industry consolidated around an animated-image standard, one which was an image, and not a video embedded in a way which looks like an image.
        • F3nd0 3y ago
          Hence why AVIF might come in handy after all!
      • JyrkiAlakuijala 3y ago
        I believe it is more fundamental. I like to think that AV1 entropy coding just becomes ineffective for large values. Large values are dominantly present in high quality photography and in lossless coding. Large values are repeatedly prefix coded and this makes effective adaptation of the statistics difficult for large integers. This is a fundamental difference and not a minor difference in focus.
        • mort96 3y ago
          > Large values are repeatedly prefix coded You mean exponential golomb style, where numbers like 0b110100101 would be encoded as 00000000110100110 (essentially using 2 bits per bit)?
• jug 3y ago
  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.
  • kllrnohj 3y ago
    > and way better than even PNG. I mean it's kinda hard to be worse than just shoving a bitmap through zlib...
  • account42 3y ago
    On the other hand, animated webp is surprisingly bad considering that the format comes from a video codec.
• derf_ 3y ago
  Usually the issue is not using the YCgCo-R colorspace. I do not see enough details in the article to know if that is the case here. There are politics around getting the codepoint included: https://github.com/AOMediaCodec/av1-avif/issues/129 https://github.com/AOMediaCodec/av1-avif/issues/129