New Scheme of Digital Watermarking Using an Adaptive Embedding Strength Applied on Multiresolution Filed by 9/7 Wavelet

摘要

Digital image watermarking is still a new field for research. In fact, digital watermarking is the best tool for the copyright protection and the authentication of the digital data. Researches are interested in the tradeoff that exists between the insertion capacity, the imperceptibility, and the robustness. The embedding function has a great influence on these characteristics. Channel coding techniques are used to reduce the error probability of the hidden watermark. On the other hand, the watermark strength is adapted according to human visual perception. In this article, we present a new scheme to achieve the embedding function in the framework of a robust and nonblind watermarking in multiresolution field by 9/7 wavelet of Dau-bechies. Indeed, we replace the constant embedding strength by a variable coefficient based on the logarithmic function. This coefficient is adaptive according to the magnitude of the wavelet transform magnitude that will be watermarked. This adaptive scheme reduces the computational error and enhances the robustness and the imperceptibility. Experimental results are presented to show that our scheme gives a better correlation and an improved PSNR. They demonstrate that the detection is enhanced.