I know Mp4tag is not a picture editor/converter, but with the introduction of the "resize cover art" feature some wishes arise
I have a car audio player which is capable of displaying embedded cover art, but limited to 99 kB of size. The resolution is not relevant to the player. Would it be possible to restrict the maximum size of the cover, e.g. by adjusting the JPEG quality?
By now, I have to open a (Linux) terminal and use a script with a command like
convert cover.jpg -resize 500 -define jpeg:extent=99000 jpg:cover_small.jpg
to get a picture with 500x500 pixels and a maximum size of 99 kB. convert belongs to the package ImageMagick.