How can I add metadata to an image?

Question

Where does one insert meta data into and image file and what it the mark up to do so? i want to do this with php.

Answer 1

I recently saw a really cool article on the w3c blog about combining RDFa and an HTML to enrich images by specifying not only what's in the image but also where it is in the image: http://www.w3.org/QA/2008/01/rdfa_and_html_imagemap.html