Simply add the addon to your browser and start using it. Toolbar button serves as an ON|OFF switch to quickly turn the addon ON or OFF. Once the addon is inactive, please reload all open tabs to remove the view image button.
Please note that, clicking on the view image button will open the images in a new tab. Also, this addon will open the image in the lightest available resolution.
In order to report bug, please fill the bug report form in the addon's homepage (http://mybrowseraddon.com/view-image-button.html).