Intercept image request

I want to intercept an image request from other web sites, runs some PHP, and then actually go ahead and serve the image request. I have ISAPIRewrite installed so I put in this RewriteRule /m.png /m.php This part is fine. To serve the image I tried -- <? // do my php stuff ?> <img src=m1.png> I use m1.png so the request is not looping back on itself. :-) It seems like this should work but it doesn't work from other web site. I think because they are expecting a raw image. So.. is this the way to go ? -- http://php.mirrors.ilisys.com.au/manual/en/function.imagepng.php right in the PHP code run -- <?php $im = imagecreatefrompng("test.png"); imagepng($im); ?> for some reason I can't get it to work for the last few hours! Anyway, if you could at least tell me if I'm on the right track I'll keep at it. Thanks! Eric http://www.mp2kmag.com