JPG text header msgbox type shit

I need to make a program that edits a jpg, specifically i want it to take in a string, and place the text on some blackspace in the image, and output the image as image-statement.jpg- whats the easiest way to do this? ive got photoshop (maybe there's easy macros?). I have basic java experience. what are your thoughts?

As much as I hate to be helpful: http://www.pythonware.com/products/pil/