Hybrid Technique for Robust and Imperceptible Image Watermarking in DWT-DCT-SVD Domain

In this paper an algorithm for digital watermarking based on discrete wavelet transforms (DWT), discrete cosine transforms (DCT), and singular value decomposition (SVD) has been proposed. In the embedding process, the host image is decomposed into first level DWTs. Low frequency band (LL) is transformed by DCT and SVD. The watermark image is also transformed by DCT and SVD. The S vector of watermark information is embedded in the S component of the host image. Watermarked image is generated by inverse SVD on modified S vector and original U, V vectors followed by inverse DCT and inverse DWT. Watermark is extracted using an extraction algorithm. The proposed method has been extensively tested against numerous known attacks and has been found to be giving superior performance for robustness and imperceptibility compared to existing methods suggested by other authors.