Does the job! Rated 5 out of 5 stars

Does what it should do, so that's perfect!
I agree that this should be standard functionality in firefox, but since it isnt, this plugin is a necessary tool.

One feature request:
Perhaps we can expand this tool with a functionality where you can change the backgroundcolor on the fly.
Sometimes seeing the images on the default black background isn't optimal, and it would be nice to be able to switch to white or grey
(or a custom color, or even a pattern (grey/white checkerboard?))

This review is for a previous version of the add-on (initial.rev24.1-signed).