I've spent the last couple of days working on an image format, based on QOI, called QOI-Remix or QOI-R. For those who aren't familiar, QOI is a lossless image format created by Dominic Szablewski; the spec fits on a page and it's enormously faster than PNG, while achieving reasonably good encoded file sizes. I thought this was a really good area to be exploring, and one relevant to my own interests and to permacomputing (under the larger umbrella of efficient software.) With that in mind, I did several changes to the image format, adding a little bit of compute overhead but frequently achieving substantial reductions in filesize - and remaining far faster than PNG.
This has been a fun project and I'm pretty happy with the result. I don't know if anyone else will find it useful, but that's okay. I've also been kicking around some concepts for a future format, from scratch instead of being a QOI variant, that would target smaller files and similar or higher throughput.
There will be a longer post about open formats from a free-software/permacomputing perspective here in the near future, but I don't have the energy for it tonight. I will just end with one observation: sustainable computing matters, and the priorities of corporate-directed codecs and formats ("reduce our network bandwidth at any cost," essentially) are not necessarily good priorities for those trying to extend useful hardware lifetimes.
Shoot me an email at sunset@arcanesciences.com if you give it a try, especially on a machine not in the "already tested" list. If you end up using it in a project, hearing about it would make my day. :)