[Zope] question on howto readfile(img)

[Wombie Tomek]

i have what i hope is a fairly easy question that's been alluding me
for a few hours.  i've been trying to rewrite a little script i wrote
in php long ago.

i need to have a script, which returns an image once it decides it
exists... the only thing i don't have worked out is how to do
something like this:

   <dtml-var RESPONSE.setHeader('Content-Type','image/jpeg')>
   readfile(img+?size=thumb);  <<----not sure how to do this, this is from php  

img being a path given through the url:     ie  ?img=somefolder/someimage.jpg

thanks,

holden