Are you writing the widget? Or are you trying to do this with, say, the ‘title’ setting for a text widget? First, though, have you tried using a valid and complete img tag for the title? I don’t know if it will work. First thing I’d try though.
If you leave the title field blank will it also be blank on the page? Some widgets will do this. If the widget you are using will allow that then just add a text widget above it in the sidebar. Don’t title the text widget but add your graphic for the widget title using html. <img src="http://yoursite.com/imagelocation"/>
see http://www.theslowcook.com/ for examples of how I did it for a client in two sidebars for multiple widgets.
Ah yeah I see what you mean about leaving the title blank I will try that thank you!
aummerchilde perfect. Thank you for giving a link to one of your sites. I went and looked at your code and volia I was able to do it. And it was easy.