Help needed redirecting a specific URL

[guitargurus]

Hello.  Say I have a link to an image http://somedomain.com/xyz.jpg and when a browser requests that image I really want it to load http://adifferentdomain.com/differentpic.jpg.  What would be the best way to go about this?  I'm playing around with dansguardian but seem to be getting nowhere.  Any help appreciated.

Thanks!