Digital Watermarking Security in the Printing and Scanning Process of Image

In this paper, a novel security method based on digital watermarking in printing and scanning is studied, and a watermarking algorithm based on discrete wavelet transform is proposed. First all, the principles and color space theory of color image watermarking is analyzed, and color distortion and geometric error caused by printing and scanning process are discussed. According to singular value decomposition and wavelet multi-resolution analysis, the digital watermarks were embedded into color image through embedding watermark into singular value of wavelet coefficients matrix. After embedding, the color image was printed with inkjet printer and scanned after the digital watermarks were embedded, then watermark extraction and Evaluation was performed. Experiment results show that the robustness and invisibility of this algorithm are strong, and that the digital watermarking proposed in this paper would be stand against general printing and scanning process. Compared with other anti-counterfeiting technology in security printing, the method in this paper has the advantages of low cost and simple implementation.