New watermark scheme for copyright protection of the stereovision system using adaptive disparity matching algorithm

Abstract

In this paper, a new watermark scheme for copyright protection of the stereo vision system using adaptive disparity matching algorithm is proposed. That is, the right image of a stereo image is formulated to 8 x 8 blocks, in which each block is composed of 64×64 and the DCT coefficients for each of these blocks are computed and then, a specific watermark image having 64 × 64 pixels is embedded into these DCT coefficients. After disparity information is extracted from both of the watermarked right image and left image using a matching algorithm, the left image and disparity information is transmitted to the recipient through the communication channel. Then, the watermark is extracted from the reconstructed stereo image using the same seed value used in the embedding process. The watermark is extracted from the reconstructed right image as a result extraction performance of a watermark tightly depends on the employed disparity matching algorithms. From some experiments using a sequential stereo image of 'Fichier' and the watermark image of English alphabet, it is shown that PSNR of the extracted watermark image from the reconstructed image by using an adaptive disparity matching algorithm improves to 3.68 dB on average by comparing with those of the pixel and block-matching algorithms.