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Comment by oofdere

2 hours ago

Yes, if you look at the demo, the "progressive" AVIF loads a visible image at 8.5KB, and at that point, it looks better than the progressive JXL. However, that is ALL the AVIF shows until the image has fully loaded. At around 98KB, the JXL looks significantly better, and at around 240KB already looks really close to the final image, while the AVIF still looks terrible. At 280KB when the AVIF finally loads, they look identical.

BTW, you can configure the AVIF encoder to have another in-between pass or two so the quality jump isn't as big. The JXL folks just happened to go with only two total passes.

  • Won't that increase the total size of the image for each pass?

    • Thanks to AV1's inter encoding, overhead is overall minimal as each pass can refine on previous ones. Think of it as a mini-video. Because of this, in the case of images with a lot of repeated patterns, progressive AVIF encoding can actually result in more efficient images!

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Which sounds very useful if your connection is slow enough to make use of progressive image decoding. (Often enough the case for me.)