Abstract—The proliferation of digitized media due to the rapid growth of networked multimedia systems, has created an urgent need for copyright enforcement technologies that can protect copyright ownership of multimedia objects. Digital image watermarking is one such technology that has been developed to protect digital images from illegal manipulations. In this paper, a new robust digital image watermarking algorithm based on Joint DWT-DCT Transformation is proposed. The imperceptibility is provided as well as higher robustness against common signal processing attacks. The watermarked image is embedded in certain sub-bands of a 3-level DWT transformed of a host image. Then, DCT transform of each selected DWT sub-band is computed and the PN-sequences of the watermark bits are embedded in the coefficients of corresponding DCT middle frequencies. Then, the same approach as the embedding process is used to extract the DCT middle frequencies of each sub-band. Finally, correlation between mid-band coefficients and PN-sequences is calculated to determine watermarked bits.

Index Terms—Keywords: Digital image watermarking, Image copyright protection, Discrete Wavelet Transform (DWT), Discrete Cosine Transform (DCT), Robustness

Cite: A Sai Kumar, K Nishanth Rao and S Narasimha Rao, "A ROBUST ALGORITHM FOR DIGITAL IMAGE COPYRIGHT PROTECTION," International Journal of Electrical and Electronic Engineering & Telecommunications, Vol. 3, No. 3, pp. 43-48, July 2014.