There is another similar script that displays a pop-up message whenever you click on an image with either mouse button. The script is a little more involved than the previous one, but is still relatively easy to implement. Another way to discourage people from printing out your images is to embed watermarks. One of the ways to watermark your image is to digitally embed your copyright information into the image itself with a program like Digimarc . Digimarc embeds information in your image which will in turn link to your identity and can be tracked across the Web.
Digital watermarks are easy to create and read.
You can also use your image editor to type in your copyright information, as I do on all my images. There's one more important tip that many people overlook. Since browsers look for an index page, if there is not one there, a complete directory listing of all of your image files will come up. The best way to stop this is to place an index page in the same directory where you have placed your images. Visit Lucid Images images directory to see how I've handled this.