Use imagemagick to watermark all image requests on the fly so you can keep changing the position of a url watermark on all images. edit - actually, don't do th

Use imagemagick to watermark all image requests on the fly so you can keep changing the position of a url watermark on all images. edit - actually, don't do this as it is trivially easy to get around by doing 2 or 3 requests and keeping anything that hasn't changed. Or if you do do this, add a low level noise filter on top so that the attacker can't just directly equate pixel values.