A method for embedding a watermark into digital data, when the watermark is to be embedded in a digital image, independently changes real number components and imaginary number components of each of coefficient values of a complex watermark coefficient matrix using key, from the watermark to be embedded...http://www.google.co.uk/patents/US7817818?utm_source=gb-gplus-sharePatent US7817818 - Digital watermark embedding method, digital watermark embedding apparatus, and storage medium storing a digital watermark embedding program
