Dither modulation of significant amplitude difference for wavelet based robust watermarking

This paper proposed a wavelet quantization based method for robust watermarking with resistance to incidental distortions. For transform domain based watermarking algorithms, blindly localizing adequate significant coefficients is one critical issue to guarantee the robustness while preserving good fidelity. In the proposed method, low frequency wavelet coefficients of the host image are randomly permutated into sub-groups according to a watermarking secret key. Embedding modifications are then distributed to important coefficients which preserve large perceptual capacity by quantizing the significant amplitude difference (SAD). Meanwhile, dither modulation strategy is employed to control the quantization artifacts and increase the robustness. In such a framework, the blind watermark extraction can be straightforwardly achieved with the watermarking secret keys which only shared by the embedder and extractor for advanced security. Numerous comparison experiments are conducted to evaluate the watermarking performance. Experimental results demonstrate the superiority of our scheme on robustness against content-preserving operations and incidental distortions such as JPEG compression, Gaussian noise.