An implementation of a technology is described herein for recognizing the perceptual similarity of the content of digital goods. At least one implementation, described herein, introduces a new hashing technique. More particularly, this hashing technique produces hash values for digital goods that are...http://www.google.co.uk/patents/US6996273?utm_source=gb-gplus-sharePatent US6996273 - Robust recognizer of perceptually similar content
