In my experience, as you increase the quality level of a jpeg, the compression level drops significantly, much more than with some other formats, notably PNG. I’d be curious to see comparisons with png and gif. I wouldn’t be surprised if the new jpeg compresses better at some resolutions, but not all, or with only some kind of images.
Lossless JPEG would be amazing.
JPEG 2000 supports lossless mode.
In my experience, as you increase the quality level of a jpeg, the compression level drops significantly, much more than with some other formats, notably PNG. I’d be curious to see comparisons with png and gif. I wouldn’t be surprised if the new jpeg compresses better at some resolutions, but not all, or with only some kind of images.
There is Lossless JPEG since 1993.