[Zope] How to get a raw image?

I need to return a rew image from a URL on my zope server, that is, I want to return a random gif using something like <dtml-var "_.random.choice(....)"> so that a user on another server can call my zope URL as http://myzopeURL.../randomimage.gif INSIDE using their HTML of the form <img src="http://myzopeURL.../randomimage.gif"> Anything I try ends up giving back HTML code of the from <img src="....my image ID..."> instead of the raw image data. Can anybody help? Greg