Digital watermarking robust to print-and-scan process

Abstract

The research on the robustness of atermarking system to the ordinary image processing techniques has been investigated for years. However, digital watermarking that is robust to D\A and A\D transformation, such as print-and-scan process, still lacks full investigation. In this thesis, we explore the property of print-and-scan distortion and present a novel watermarking scheme robust to this distortion. We find the feature space robust to print-and-scan distortion within images consist of the smooth image blocks. Thus we embed the watermark by generating new smooth blocks in some pattern. As this bind watermarking scheme needs the texture blocks for reference, we design a noise adding operation to compensate the print-and-scan distortion to the texture blocks. A multiple-vote operation is also designed to enhance the robustness of watermark extraction. Experiment results show that this watermarking scheme is robust to the print-and-scan distortion for different images.