Add Notes Over Images With Fotonotes
Fotonotes is a collection of scripts for annotating images. Simply, it lets you add notes over images.
With the help of a PHP file (supports PHP4 & PHP5), every note added to the images are stored in JPEG headers in XML format.
There is a very nice example on the website which you can try the code.
Download package includes classes for alternate storage strategies like databases.
Compatibility: All Major Browsers