Header Insert Question

This may not be possible, but then again I'm ignorant of these things. I'm using an insert header plug-in and put a banner in so that all themes have it. Is there any way that I can make that banner match the width of the theme automatically and constrain the proportions?

I know php is powerful, but is this possible?

If so, id need somebody to code it for me. I pay! lol

This would be an awesome plug-in because I see people all the time asking if they can put a header on all their themes without going into each theme individually.

Thank you for the help, as always I appreciate and value your input.