Hybrid Color Watermarking Technique with Arnold Scrambling

Digital watermarking is one of the best techniques to protect the digital data from unauthorized access and provide copyright protection. Imperceptibility and robustness are the important features of digital watermarking. Color image watermarking method based on discrete wavelet transform (DWT), all phase discrete cosine bi-orthogonal transform (APDCBT) and singular value decomposition (SVD) is proposed in this paper. In this technique we hide a color image watermark into a color cover image balancing both imperceptibility and robustness. The three level DWT is applied to the Luminance (Y) channel of the color cover image. Block based APDCBT is applied to the resultant diagonal details (HH) sub band and the DC coefficient matrix is generated for SVD which then embeds the Red channel of the watermark image after implementing security with Arnold Transform followed by DWT and SVD. APDCBT transform is used instead of conventional DCT to reduce the block artifacts at low bit rates. The main reason to use the DC coefficient after APDCBT is to enhance the watermark imperceptibility. Furthermore, the proposed method achieved high robustness in resisting various signal processing and geometric attacks. This is justified by comparison with the reference watermarking method that doesn't implement the Arnold transform. Comparatively, the proposed algorithm has the better robustness for the most of the single attack as well as the mixed attack cases than the reference method.