Patent ID: 8014035

Claim:
A method for decoding data embedded in an image via halftone dot orientation, the method comprising: scanning an image print containing a data message embedded therein, said message comprising a plurality of single data values, each single data value taking only one unique state; synchronizing said scanned image to a uniform periodic tiling utilized for generating said image print to compensate for geometric distortions introduced by print/scan processes performed on said image print; associating a unique orientation direction with each of said unique states, each of said unique orientation directions being oriented with respect to a horizontal and vertical axis of said scanned image print; defining a uniform periodic tiling for said scanned image; and for each of said uniform periodic tiles in said uniform tiling, calculating a plurality of image moments for a halftone dot of a current tile, one image moment being calculated along each of said unique orientation directions; determining a largest of said calculated moments, said largest moment identifying a dominant orientation direction for said halftone dot; and decoding a single data value embedded in said current tile based on which of said unique states is associated said determined dominant orientation direction.