Picture Watermarks Surviving General Affine Transformation and Random Distortion

We have extended a previously reported method immune to random distortion to make it immune to affine transformation as well. Although affine transformation consists of four geometric transformations (scaling, rotation, translation, and shearing), the proposed method requires only scale and rotation searching. Experimental evaluation showed that it can detect each geometric transformation. It can thus be used to create picture watermarks that are immune to a wide variety of geometric transformations.