A watermarking algorithm based on chirp z-transform, discrete wavelet transform, and singular value decomposition

Digital watermarking has attracted increasing attentions as it has been the current solution to copyright protection and content authentication which has become an issue to be addressed in multimedia technology. This study introduces a novel watermarking scheme based on the discrete wavelet transform (DWT) in combination with the chirp z-transform (CZT) and the singular value decomposition (SVD). Firstly, the image is decomposed into its frequency subbands by using 1-level DWT. Then, the high-frequency subband is transformed into z-domain by using CZT. Afterward by SVD, the watermark is added to the singular matrix of the transformed image. Finally, the watermarked image is obtained by using inverse of CZT and inverse of DWT. This algorithm combines the advantages of all three algorithms. The experimental result shows that the algorithm is imperceptible and robust to several attacks and signal processing operations.