The extension is intended to complement image features that (I think) is missing from Opera by default or give features that are just simply useful.
Enlarges thumbnails and linked images (or even linked thumbnails) into a popup with just a mouse hover.
Replaces the browser's default image resizer to a more customizable version. For instance, it's possible to set the initial sizing mode or disable the resizing totally. More Info »
* Opening images
* Send image to...
This is a set of rules which are helping the extension to find the larger images.
This is something like a bookmark for images. It stores only the image address with a thumbnail, and if possible, then one or two source link. The "Source", which is the address of the page where you've seen the image, and the "Target", which is the address of the link (if it wasn't the same as the zoomed image address).
When an image is opened or "hoverzoomed", then pressing the shortcut (G by default) will add it to the list without any questions. Shift + G will prompt for labels. Deleting images from the list: Ctrl + Right click on the thumbnail cell or Ctrl + Click to select some and the minus button from the button-list. Shift + Right click on a cell to edit the labels.
At Grants you can tell on which sites can the extension work.
It's also possible to block just some Sieve rules.