Normally, you can right-click the image and then shift+click the menu item to overlay image info onto the image. Are there sites where that isn't working?

Currently, there is no obtain any information without first right-clicking the image. If it would be useful to automatically label some or all images, I could consider that as a new feature. Feel free to start a new request at https://github.com/jscher2000/View-Image-Info-Reborn-for-Firefox/issues with more information about how you want it to work.