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The proposed copyright protection scheme combines the discrete cosine transform (DCT) and singular value decomposition (SVD) using a control parameter to avoid the false-positive problem. In this article, we propose an efficient copyright protection scheme for e-government document images. First, we apply the discrete cosine transform (DCT) to the host image and use the zigzag space-filling curve (SFC) for the DCT coefficients. The DCT coefficients in the zigzag manner are then mapped into four areas with different frequencies in a rectangular shape. Then, we apply the singular value decomposition (SVD) operation to each area, and the host image is modified by the left singular vectors and the singular values of the DCT-transformed watermark to embed the watermark image. The left singular vectors and singular values are used as a control parameter to avoid the false-positive problem. Each area decides the scaling factor's optimal value using a genetic algorithm (GA) with the mean of the watermark's SVs. A scaling factor is simulated by chromosomes, and several optimization GA operators are used. After remapping each modified coefficient DCT back to the original position, the proposed inverse DCT produces the watermarked image. Our experimental results show that we can improve the image quality GA-based evolution and that this approach is robust under several kinds of attacks.
Date of Publication: July-Sept. 2012