Due to filesize concerns, we optimized the Volna wallpaper to be JPEGs compressed at 90% quality.
JPEGs seems like the right way to go, but at 90% JPEG artifacts appear, as well as a noticeable loss of sharpness. Both are more prominent the smaller the resolution.
I used the same tool (squoosh) to generate more high quality JPEGs, paying attention to how each resolution responded to a certain quality setting.
In the end I had to use values between 94 and 98 in order to ensure there is no noticeable difference with the original PNGs.
This brings up the total file size to 17.4 MiB, which I think is still fine, especially given that this is our default wallpaper for an LTS release.
