Non-blind watermarking Scheme for Colour Images using Discrete Wavelet Transforms and Singular Value Decomposition
|Madhavi Prathapaneni1 and Gunasekhar Reddy N2
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The rapid proliferation of multimedia over internet demands sophisticated technique for secure and efficient access to information. There is growing need to discourage unauthorized duplication and use of digital data. To provide copyright protection for colour images, an effective, robust and imperceptible watermarking scheme is proposed. Because of its growing popularity, the Discrete Wavelet Transform (DWT) is commonly used in recent watermarking schemes. In a DWT-based scheme, the DWT coefficients are modified with the data that represents the watermark. In this paper, we present a hybrid non-blind scheme based on DWT and Singular Value Decomposition (SVD). After decomposing the cover image into four bands (LL, HL, LH, and HH), we apply the SVD to each band, and modify the singular values of the cover image with the singular values of the visual watermark. Modification in all frequencies allows the development of a watermarking scheme that is robust to a wide range of attacks. We compare our hybrid algorithm with a pure SVD-based scheme, and show that it is considerably more robust and reliable.