Recovering Watermarks from Images

Many techniques for watermarking of digital images have appeared recently. Most of these techniques are sensitive to cropping and/or a ne distortions (e.g., rotation and scaling). In this paper we describe a method for recognizing images based on the concept of identi cation marks; the method does not require the use of the \original" image, but only a small number of salient image points. We show that, using our method, it is possible to recognize distorted images and recover their original appearances. Once the image is recognized we use a second technique based on normal ow to ne-tune image parameters. The restored image can be used to recover watermarks that were embedded in the images by their owner. Also with Computer Science Department, George Mason University. Also with Information and Software Engineering Department, George Mason University.