r/jpegxl

I've been reading the PDF on the JPEG XL Image Coding System, and I was drawn to the patches system which is good for images with lots of repeating elements like letters or icons. Although the PDF I have doesn't really explain how the algorithm for finding them works. I thought maybe an algorithm just goes through every possible patch of the image that is less or equal to a quarter of it, but that would take too long, so I wonder, how are these patches found?

I kept noticing that the interesting thing about a burst of photos, or five tries at the same shot, is the series itself. Not any single frame. But there was no good way to watch them as a series. Slideshow apps cross-fade and Ken Burns everything into mush, and the video apps want to interpolate, stabilize, and "enhance."

So I built Flipbook: https://flipbook.photos

It plays your photos back slowly enough that you can still see they are photographs: each one held for a beat, then a hard cut to the next. The feel of a flipbook or early film. No filters, no grain overlays, no generated frames. The whole effect comes from timing.

Here it is running the oldest photo series there is, Muybridge's galloping horse from 1878: https://www.reddit.com/r/stopmotion/comments/1vlu2hr/

A few things I cared about:

• Your photos never leave your device. Decoding and H.264 encoding happen in the browser with WebCodecs. There is no upload step at all.
• Honesty to the originals. Nothing is retouched or invented. The one optional feature that crops anything (auto-align, for handheld drift) is off by default and tells you exactly how much it trimmed.
• It reads your camera roll the way you shot it. It sorts by EXIF capture time and auto-groups photos into series wherever there is a gap of more than ten seconds, so a dump of forty photos organizes itself into the three moments you actually shot.
• The output actually works. A true 5 fps video breaks iOS Photos and iMessage, so it encodes at a normal frame rate with each photo repeated. You get an MP4 that saves straight to your camera roll and posts anywhere.

Good for kids growing up in the same doorway, a friend mid-laugh across five frames, construction progress, a dog failing to catch something.

It is free for your first three videos, then $12 for a year. No account either way. The code is public if you want to see how the in-browser encoding works: https://github.com/mzrascoff/flipbook

Would love to know what breaks, especially on Android browsers.

Anyone can test it at https://masland.tech/jxl/

If you have any issues or questions please let me know. This is a prototype to just see if I can host this successfully. It can take over 15 seconds for an image to be converted, so please be patient. Thank you for testing it if you do.

I'm working on a maximum effort lossless JPEG XL converter and I was struggling to figure out why a lossless PNG was coming out larger as a lossless JXL. The image has a very flat black background. I believe I was using effort 7 which is default, and it was coming out about 15% larger, then I increased the effort to 10 and now it's about 20% smaller.

I should have it hosted soon, but just wanted to share my experience with this. Given that I'm fine with waiting longer for a conversion, my main concern being size and quality. I think having a lossless maximum effort converted online with a queue system will be beneficial.

If anyone has any recommendations please let me know, I will be posting once it's live in the near future, thanks for reading.

Just added JPEG XL support to ServeProxy. Add ?jxl=true before your existing ?url= parameter and it'll convert and cache the image as JPEG XL on the fly. AVIF is the default output format on Serveproxy, so this gives you a second modern format to compare against.

Example: https://serveproxy.com/?jxl=true&url=https://picsum.photos/1000/750

Browser support is still limited so test before you rely on it in production, but if you want smaller images with good quality it's there now. 🙂