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Comment by obituary_latte | Hacker News Reader

I wonder if there is a way browsers could preemptively “compress“ (I doubt that’s the correct terminology) prior to downloading? Like somehow grab every nth bit, combine, render and then allow for further requests to refine at user discretion. Wonder if anyone has ever tried something like that.

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This feature is built into Jpeg images, though most image editors don't save them with this enabled by default. People call them progressive jpegs.

https://www.thewebmaster.com/dev/2016/feb/10/how-progressive...

Used to be really common around the late 90s/early 2000s...

I know that Opera had this feature once and Google Chrome on Android does this via it's "Lite mode":

https://support.google.com/chrome/answer/2392284?co=GENIE.Pl...

This used to be a feature of Opera. If you enabled it, it would run all webpages through the Opera proxy, which would downsize everything for you.

The wavelet-based image formats like JPEG 2000 were designed to make that sort of thing possible. They never really caught on, though.

I don't think that's even possible with the byte-ordering of a lot of the formats we use today.

Like the pass extraction of PNG [0] would make it somewhat possible, but you'd need to be dropping packets which you might as well receive. I don't think you'd be able to break after the first pass.

JPEG is probably worse.

However, the super-modern formats that are still gaining popularity, like WebP absolutely do support this. At the core of WebP is block prediction, so a low-bandwidth application might actually assume the values of certain blocks so it doesn't need to fetch them.

[0] https://www.w3.org/TR/2003/REC-PNG-20031110/#4Concepts.Encod...

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