Geometric robust watermarking through watermark pattern shaping

In this paper, a watermark pattern design approach is proposed to combat the general geometric attacks to watermarking systems. Geometric attacks pose a major threat to most existing watermarking systems by destroying the synchronization between the watermark patterns and the watermarked images. We propose to shape the watermark patterns so that the output of the correlation-type demodulator is in the shape of a specified function. Such a watermark pattern shaping can be used directly to combat moderate geometric attack, or used with other watermark schemes to improve decoding performance. A design example of the shaping filter is presented. Experiments show that the proposed watermarking scheme can survive survive (1999) bending attack to a wide range.