Space Time Block Coding for Spread Spectrum Watermarking Systems

In this paper, we propose a novel spread spectrum image watermarking system. It employs Alamouti's space-time block coding scheme which is commonly used to improve the performance of the wireless communications. We model the digital watermarking system as a wireless communication channel and take the advantages of space-time block coding scheme. We employ 2x2 real orthogonal design for embedding watermark sequence into the host image in discrete wavelet transform domain. The goal is to enhance the robustness of the spread spectrum watermarking system against various degradations and malicious attacks. Simulation results show that the proposed promising system considerably increases the correlation and decreases the bit error rate between the embedded and the recovered watermark sequences.