In almost WordPress themes, especially with default WordPress themes (twentyeleven, twentyten, etc); when click on a particular image to view the original or large version of the image you have to leave the current page and be redirected to another page with just an image.
In order to display large or original version images right on the current page with dark or light background which dims the page over which the image has been overlaid, I’m using Lightbox Plus WordPress plugin which easily to setup and download file is available from WordPress Lightbox Plus.
Basically, Lightbox Plus implements lightbox image overlay tool for WordPress, easy to setup, configure and run with cross browser/flatform compatibility.
Lightbox Plus With Multiple Images On A Page
Lightbox Plus With Just One Image
Note: I’m using Lightbox Plus Stype: Framed. You can change the settings in the Dashboard via Appearance => Lightbox Plus.
You can download the Lightbox Plus WordPress plugin from http://wordpress.org/extend/plugins/lightbox-plus/. Enjoy!