I have the latest version of Mozilla Firefox and after I tried this add-on, my images were completely gone - even when I disabled this add-on, deleted it, restarted my PC.
I installed it again and tried to delete again, didn't help.
I ended up refreshing Mozilla, so all my add-ons, themes, etc. are lost now. God bless the Firefox Devs for saving at least bookmarks, journal and tabs.
Thank you very much. I only wanted to have a convinient tool to turn it on the sites which are loaded with unnecessary photos and turn it off, when I'm actually googling PICTURES.
Not happy at all. Sorry.