Real-time stereo image watermarking using discrete cosine transform and adaptive disparity maps

In this paper, a real-time stereo image watermarking scheme using discrete cosine transform(DCT) and disparity map is proposed. That is, a watermark image is embedded into the right image of a stereo image pair in the frequency domain through the conventional DCT operation and disparity information between the watermarked right image and the left image is extracted. And then, the disparity data and the left image are simultaneously transmitted to the recipient through the communication channel. At the receiver, the watermarked right image is reconstructed from the received left image and disparity data through the adaptive matching algorithm and a watermark image is finally extracted from this reconstructed right image through the decoding algorithm. From some experiments by using the stereo image pair captured by the CCD camera and a watermark image of English alphabet 'NRL', it is found that the PSNR of the reconstructed right image through the DCT and adaptive matching algorithm improves to 9.3dB by comparing with those of the reconstructed right images through the conventional pixel-based and block-based matching algorithms. At the same time the PSNR of the watermark image extracted from the reconstructed right image also improve to 7.72dB by comparing with those of the others. These experimental results suggest a possibility of practical implementation of a disparity map-based stereo image watermarking scheme.