Systems and methods of detecting halftone modulations that are embedded in an image are described. The halftone modulations represent an ordered sequence of digital halftone microscreens that encodes information that has been embedded in the image. In one embodiment, the embedded information is detected...http://www.google.com/patents/US6839450?utm_source=gb-gplus-sharePatent US6839450 - Detecting halftone modulations embedded in an image
