It would be nice to have the image compression quality (e.g. JPEG 94%) displayed in the image properties window. (It currently only shows JPEG without the quality).
I assume this is possible, because IrfanView can do it:
The program already has something like estimated compression quality. This is in the preview of a specific image in the browser - click on details. This is an estimate that is very misleading for files created by the jpeli codec, which creates significantly smaller files than the traditional jpg codec.
Ah, it shows up as "Estimated quality" in the image properties indeed, but only if I enable the following option in Settings:
Formats -> Write -> JPEG -> Use estimated quality (when possible)