Copy/Paste image blocker into https://addons.mozilla.org/en-US/firefox/extensions/ There is a couple there. Am sure there will be more in time as people finish coding for the requirements for security. Give it time where there is a need someone will step in. If configure Ublock to block the image servers then that works but is a pain to do for each site then reverse when want to look. Please let us know if this solved your issue or if need further assistance.