As many of you know, modern color copiers/Photoshop detect currency and refuse to scan/open such images. There has been some work in reverse-engineering what algorithms are used to determine what is currency. I am very much interested in expanding this work towards the end of creating false positives. [Think like a T-shirt that when worn would make you difficult to photograph, or artists discreetly embedding such watermarks inside photos that they dont want photoshopp'ed, etc.]
Consider this a call for any comments/knowledge relating to this issue.
Also see: http://www.wildspark.com/eurionize/
[ Very interesting thought. I'm afraid I don't have any expertise to assist, but I'll bump this thread at least... -k]
Photoshop Currency Detection