Today I've decided to experiment with HEIF that was introduced by Apple with macOS 10.13 and iOS 11. They said that it has the same quality with much lower file size.
It's supported in the latest versions of macOS and iOS and last models of iPhone can take pictures in that format.
I'm thinking about compressing my home archive of photos and videos. I was experimenting with HEVC (H.265) and results were great - I had reduced the size of my videos by encoding them to HEVC with an awesome util called HandBrake.
I found the only way to convert JPG to HEIF (which has HEIC extension). It's possible with the Preview app from macOS. But it would be interesting for me if I can do it by myself in Swift. So I did :)
My folder with 64 photos from my action camera was 203 mb in JPG format. And it's only 31.3 mb in HEIC.
macOS and iOS support it from the box. And what's interesting - it's easy to add pictures in this format to the Photos library and it will appear on all your devices that use iCloud. But if you want to export this picture from the Photos library - it will be converted to JPG on the fly, so it looks like you can't export the original HEIC file.
The converter is free and open source (but it's for macOS only): https://github.com/makoni/jpg-to-heif-converter