> I want it converted silently, I don't want an annoying popup displayed on each picture, even on those that don't need to be converted

* No automatic info / button bar *

On the Add-on's Options page, under "Button Bar Options", look for "Open bar automatically" and make sure it is *not* checked.

* Silent Save *

On the Add-on's Options page, under "Menu Item Options", you can set the "Plain click" action to save in your preferred format instead of showing buttons. Under "Save Dialog / AutoSave Options" you can control whether to show a Save As dialog or not.

I think that should resolve your concerns, but let me know if you don't find those options.