Zoom in and out on images and videos using shift + mouse wheel and by other ways.
This extension works "inline", i.e. images are not displayed in a popup - instead they are enlarged exactly where they are.
Press shift (customizable) and use mouse wheel to zoom in or out an image or video under pointer.
It's open source: https://github.com/kpion/inzoom
If you have any suggestions, please don't hesitate to reach me on firstname.lastname@example.org or file an issue on the github page above.
New in version 1.31: Keyboard shortcut to enlarge a photo and bring it to the front in one step (alt + a).