imanu - image manipulation — Hagen Schnuch

Basic in-browser image manipulation to change saturation, contrast, brightness, etc. of images directly in your browser. You can also shrink oversized images and then save the manipulations you did to a new file.

Click here for a demo! (https://schnuch.gitlab.io/imanu-demo.html)

This add-on is still in early development!
More features and little changes for a more comfortable UI are planned.

You may encounter problems when you're using this extension simultaneously with other add-ons that modify the image preview of Firefox.