Live data from Hacker News

Regressive JPEGs

maurycyz.com

31–40 of 72 posts

Re: Regressive JPEGs

#31
post #21

I wonder if and how you can use this for steganography, hiding data in plain sight. I bet most automated image analysis programs would only consider the final image. I sure some highschooler can use this to bypass their schools contentfilter

I can't see any way this would beat regular steganography.

Re: Regressive JPEGs

#32
> “Besides unconventional rickrolls and other trolling, this has no practical applications: there's no way to add timing information, so playback is entirely dependent on network delay.”

A progress bar for something that’s loading in parallel over the same network, to give the user an idea of how much the delay is?

Re: Regressive JPEGs

#33

I wonder if you can do this in JPEG-XL. I know that that has actual animation support, but this would be a different thing.

The format supports progressive decoding but IIRC none of the current browser implementations support it. The first Chrome and Firefox implementations did, and I think it's on their roadmap for the new Rust implementation. No idea about WebKit/Safari. Edit: the format also supports region-of-interest decoding and I suspect you can make some cool maps or fractal images with both features. But I think they're not quite…

> The first Chrome and Firefox implementations did

I was about to say: I'm sure I've seen it work a t some point? I imagine it's a valuable thing to add for the web though. It would be really cool if you could use the same image source for thumbnail and full image, and the browser both just figures out how much to download based on pixel size and can resume previously partially downloaded images.

And yeah, the tiling isn't implemented anywhere yet, jxl doesn't really get enough funding for that. But it'll be really cool once it does since it also makes it really useful for giant images of geographic data. I don't know if it combines with streaming downloads as well, but it would be crazy cool if we effectively got OpenSeaDragon[0] support inside an image format

[0] https://openseadragon.github.io/

Re: Regressive JPEGs

#34
Wow, Firefox never fully loads the page, while WebKit fails to load it altogether, instead it displays "Operation was cancelled" in system font after a short freeze. I didn't manage to see the images change in any way as the post would suggest though, which left me confused.

Re: Regressive JPEGs

#36

Adjacent advice: I've recently played with opengl and jpeg turbo and I wanted to display images fast. I don't remember exact numbers, but enabling progressive for a jpeg was a significant slowdown for decoding. So if anyone like me is stuck with the old school advice that progressive is an nice to have, it's likely not. I personally don't remember any visual progressive image buildup in like decades, so it's not doin…

I use cjpegli as encoder and it compresses best with its default progressive and full 4:4:4 approach, so it's not only a nice to have feature.

I deliberately was talking about decode speed. The question is if you serve even via moderately fast infra, does it display faster? In my case on a (indeed fast) local system absolutely not. Mere size can be a decode problem of course. But it's extremely hard to tell that a single digit percent size difference is an advantage for serving.

But if better compression for storage or you can verify progressive serves faster then it is of course a benefit.

I guess the point I am making is that most people think: I heard it's somehow better so lets use it.

Re: Regressive JPEGs

#38
post #23

Adjacent advice: I've recently played with opengl and jpeg turbo and I wanted to display images fast. I don't remember exact numbers, but enabling progressive for a jpeg was a significant slowdown for decoding. So if anyone like me is stuck with the old school advice that progressive is an nice to have, it's likely not. I personally don't remember any visual progressive image buildup in like decades, so it's not doin…

Progressive decoding isn't expected to speed up decoding, it's expected to speed up displaying large image files, especially for downloads via slow mobile connections. Example: https://youtube.com/watch?v=UphN1_7nP8U

I've started using computers in the 90s, I've seen this every day back then.

Still the question is, does it help? Trying to access an average web app will probably take minutes before the browser may even see an image. If you do everything possible to render reasonably fast on very slow speeds, then progressive is nice. On a fast connection I don't think the average user will notice the difference.

Re: Regressive JPEGs

#39
post #13
post #7

That is 1. Cursed, and 2. Definitely in the right place here.

This is the stuff that I come here for.

Weekend HN is definitely where the more interesting and offbeat content lives, and I often find myself enjoying it significantly more as a result.

During the week, well, it would be unfair to call it LinkedInified, but it can often feel like a somewhat higher tier of that sort of strata. Plenty of good stuff in there still, but much more “serious business”.

Re: Regressive JPEGs

#40
post #21

I wonder if and how you can use this for steganography, hiding data in plain sight. I bet most automated image analysis programs would only consider the final image. I sure some highschooler can use this to bypass their schools contentfilter

Yep this is an AI subversion technique for sure. Put the message to the humans in the first frame, and the message to the AI in the final frame. This is how we defeat skynet: by sending each other pictures of cats.

You could probably implement a server that is purposefully slow enough so that the human frame shows up for however long you want. Just need to send the keepalive bytes one-by one.
Post reply on HN