A Digital Image Watermarking Technique Using Cascading of DCT and Biorthogonal Wavelet Transform

Modern communication technology facilitates easy transmission of multimedia content. But if copyright protection of multimedia data, prevention of illegal access, and rights of intellectual property are considered, so this field needs more attention of researchers. It is a very simple process to make a copy of the multimedia data, alter it, and then put it back for business profits. Digital watermarking techniques provide a solution for this issue, by embedding some information, which can be further used to claim the ownership of multimedia data. In this paper, a new algorithm for the watermarking of digital images is proposed by cascading of two frequency domain transform techniques, i.e., biorthogonal wavelet transforms (BWT) and discrete cosine transform (DCT). Proposed technique takes the approximation component of the biorthogonal transform of cover image and then applies DCT to embed watermark. Embedding of watermark data is done in middle frequency component by comparison-based correlation technique. Also, this technique has been analyzed and compared with the existing ones by applying various image attacks and subsequently measuring the results and proved to be fairly robust.