Discrete Cosine Transformation Based Image Watermarking for Authentication and Copyright Protection
Ritu Pareek1, P.K. Ghosh2
1Ritu Pareek, Department of Electronics and Communication Engineering, Faculty of Engineering and Technology, Mody Institute of Technology and Science, Lakshmangahr, Dist. Sikar, Rajasthan, India.
2P. K. Ghosh, Department of Electronics and Communication Engineering, Faculty of Engineering and Technology, Mody Institute of Technology and Science, Lakshmangahr, Dist. Sikar, Rajasthan, India.
Manuscript received on January 17, 2012. | Revised Manuscript received on February 05, 2012. | Manuscript published on February 29, 2012. | PP: 152-156 | Volume-1 Issue-3, February 2012. | Retrieval Number: C0212021312/2011©BEIESP
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© The Authors. Blue Eyes Intelligence Engineering and Sciences Publication (BEIESP). This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)
Abstract: In this paper, a digital image watermarking algorithm based on DCT transformation is proposed. The imperceptibility and robustness is provided against different attacks. A binary image is embedded in the host image by two different techniques based on DCT. One is middle band coefficient exchange technique, it utilizes comparison of two middle-band DCT coefficients to encode a single bit into a DCT block. Coefficient locations are selected based on the recommended JPEG quantization table. Second is based on PN sequence, PN sequences of the watermark bits are embedded in the coefficients of the corresponding DCT middle frequencies. In extraction stages, the watermarked image, which may be attacked, is processed the same way as the embedding process. Finally, correlation and PSNR values are calculated to determine the level of accuracy and imperceptibility. Experimental results show that the proposed method improved the performance of watermarking algorithm.
Keywords: Discrete Cosine Transform, Digital watermarking, PN Sequence, Middle band frequency, Copyright protection, CDMA.