I would kindly suggest that instead of showing an obscene image, that you should just have an image that says something like:
Dear Google Employee:
This image was stolen from MY website at mydomain.com
Because one of the first things that someone is going to look at is an image on the page (that might be the only thing they look at), and if they see an image on their site that is different than the image on your site, then maybe they will think they DIDN'T scrape you (crazy, but possible - I am sure google employees are overworked, too).
anyway, it is just a thought. I know showing an obscene image might make you FEEL better, but maybe showing an image that displays the URL to your original page will help you in dealing with the DMCA reports.
Hope this helps.