GC and AppleScript to change DPI

[inigokwik]

I have created a AppleScript Droplet. This does all kind of operations to any number of jpg's that I drop on it. One thing I want to add, but haven't been able to implement is a change DPI. I have failed with SIPS, Image Events and until now also with Graphic Converter. Perhaps someone here can help me out? Thanks, Inigo