You get even more functionality with https://addons.mozilla.org/en-US/firefox/addon/hide-images-per-tab. Plus, it works with Firefox 57 and newer.

Was mag der Sinn dieses addons sein? Funktioniert nicht mit ff-64, generell. Nur mit x32 sind paar Ergebnisse erzielbar, und sichtbar. Also mit x64 nada, mit x32 so la la.
=> Nicht überzeugend!

After installing this, I got a pop-under advertisement, and upon reboot, Avast warns that this addon has "bad reputation among Avast users".

Follow the advice of the other review, access options and just "save". Unfortunately it resets your choice for every new page (stops loading all)

Working perfectly on Firefox for Linux 49.0.2 after resetting the default extension preferences. Great!