DWT-domain Dual Watermarking Algorithm of Color Image based on Visual Cryptography

Considering the combination of digital watermarking technique and visual cryptography, this paper proposes a new dual watermarking algorithm of color image. The first watermark is embedded into the high-frequency part of discrete wavelet transform (DWT). Using visual cryptography, we process the second watermark to generate two shares, then one of them is embedded into the low-frequency part of DWT and another is protected by the copyright. The experimental results show that this kind of new algorithm has high security. In addition, the embedding capacity of watermarks and robustness are improved effectively.