A Simple Way to Specify Image Licenses

Google has recently added a Creative Commons filter in Google Image Search, but it didn't explain how to specify the license so that your images are properly identified.

The trick is to enclose the image and the license's link in a div tag and to use RDFa's about attribute to specify the resource. For example:

<div about="image.jpg">
<img src="image.jpg" alt="" />
<a rel="license" href="http://creativecommons.org/licenses/by-sa/3.0/">Creative Commons Attribution Share-Alike 3.0</a>
</div>