Document Image Watermarking Scheme with Adaptive Positioning Based on Discrete Wavelet Transform and Discrete Cosine Transform

An important technology for copyright protection is digital watermarking, which generally embeds copyright infor-mation into the carrier invisibly. In the case of various attacks, the identity of the watermark can also be extracted to prove its copyright from the carrier of the watermark. Most of the existing watermarking technologies use natural images as carriers. Unlike natural images, document images are not rich in color and texture, and thus carry less redundant information for watermarks. This paper proposes a adaptive positioning document watermarking algorithm based on Discrete Wavelet Transform(DWT) and Discrete Cosine Transform(DCT). The method integrates adaptive positioning algorithm, discrete wavelet transform, discrete cosine transform and other algorithms. In our case, we first scan the document image to adaptively embed the keypoints information, so that even if a part of the document is recorded, the complete watermark area can be accurately located. Secondly, we construct the watermark embedding regions centered at keypoints. Third, the DWT and DCT algorithms are used to embed the watermark, which achieve strong robustness to the capture process attack. Finally, the watermark can be extracted from at least one region in the extraction stage. Compared with the previous watermarking algorithms, the proposed approach not only ensures the independence of embedded content, but also is robust to various noise attacks. In addition, the method can meet the extraction accuracy requirements even when the document image is incomplete.