Yep, it was one of the ways to have an animated avatar on BB forums.

Most recently, I have seen them being used in animated chat stickers (like on Signal).

Would this be the Gif killer? If PNG can contain a relatively similar frame count & time limit but with marginally better image quality it just may.

It's great that Papua New Guinea is still receiving updates /s

That’d be the browser’s (or whatever app you’re using) fault, not the format. I guess you could choose to hate it for poor support.

That was because they added 'shorts' and friend-lists to it.

So it depends on the specific HDR encoding used, Rec2020 is the most common ones you'll see (It's meant for "pure" setups, i.e. where the source and output are tightly linked, e.g. gaming consoles or blu-ray, or so) and the raw data won't look great. While something like HLG (Hybrid-Log Gamma) is designed for better fallback (As it's meant for TV broadcast, where the output device is "whatever TV the user has"), so should just look dimmer.

This is a HDR screenshot I took of Destiny 2, which uses Rec2020, tone mapped to SDR

And here's the raw screenshot data from before tonemapping.

If the second image had all the right HDR metadata, and the viewer supported it properly, then both images would match.

lossless recompression of existing JPEG
Uh… how does it make a JPEG lossless? Or is it lossless in that it makes a JXL out of a JPEG without affecting the original JPEG quality (i.e. no further loss beyond JPEG's)?

Being able to turn JPEGs into JXLs and JXLs back to JPEGs is cool, though

What's with the AVIF thing? Yet another I am unfamiliar with (all I know about image formats is JPG = worse quality, PNG = better quality, GIF = animated (and something WebP. Idk much about that one either))

Also, in my research, I've found something about the distinction between lossless JXL vs lossy JXL. Seems like you wouldn't be able to tell if the image is lossy or lossless just from it being a JXL

WebP is the same, it's got a lossy mode (VP8) and a lossless mode (Which is more limited than PNG, but beats it where it overlaps). But to make it more complicated the lossless mode also has lossy processing modes, where it alters the image first to achieve smaller output sizes.

And PNG is no different.

People have a long habit of turning JPEG files into PNG files, the file extension won't help you there. They also could have reduced the colour depth or resized it, all lossy operations. All it really tells you is that it can have an alpha channel.

As for AVIF, personally I don't like the format, it feels like an "open media" (But still patented) version of HEIF to oppose Apple. Like WebP it makes the (baseless IMO) assumption that a format designed to encode motion data is better at encoding still data than a format designed to encode still data. It's got all the limitations of a video format (It's got a max resolution, only supports 12bit images, and no progressive decoding), and they left out all the enhancements from WebP (The dedicated lossless mode, "lossless AVIF" files are huge and the last I checked badly supported, so nobody actually used them, and they just called very high quality settings "lossless")

A team inside of Google was working on WebP2 around the same time, that used AV1 but actually added the useful stuff like efficient lossless encoding, it got killed too in favour of AVIF.

To ELI5 this, this happens when whoever made the webpage put a text layer above the image - probably on purpose to make it harder for people to download the image.

Ooh, Alpha channel. Forgot of that. That is a nice one. Love me some alpha channel.

So, what would you say is best? If someone wanted to save an image, which format would you recommend? I usually go with PNG. JPG if I want bad quality on purpose (drag quality slider to minimum for extra compression)

PNG gets you the best compatibility and features, at the expense of file size. But I probably wouldn't use it for uploading photographs to the web of course.