A Method for Resisting Averaging Attacks on Digital Watermarks and Use of This Method with Digital Watermarks

A method is proposed for resisting averaging attacks, in which many users collude to make an average image in which the watermarked information is canceled out. This method works by minutely and uniquely changing the original image for each user (purchaser), which degrades the quality of the average image. A basic experiment showed that the greater the number of images degraded, the more effective the proposed method. Another experiment showed that the method is more effective when images with large distortion parameters are combined.