mooZoom is an unobtrusive javascript utility that allows you to zoom an image in the desired point using mouse-scroll. It does not break the layout of the page and it's cross-bowser (ie, opera, firefox, safari).
witching images is no different from opening them; just call the openDzi() method. If you don't want to show any image, you can call the close() method, but this is not required.
When you add in a way for the user to choose the image (like we've done below), you're more than halfway to building your own image gallery.