An Adaptive Watermarking Algorithm in DWT Domain Based on Multi-scale Morphological Gradient

An adaptive watermarking algorithm in the wavelet domain based on multi-scale morphological gradient is proposed in this paper. Using multi-scale morphological gradient, the distribution and the strength of the sub-block texture after the wavelet package decomposition are analyzed, and the textures of sub-blocks are sorted. According to the texture feature of the sub-block, the sub-block threshold is determined adaptively and the position which is bigger than its threshold is selected as the important coefficient position where the watermarking is embedded. Then, the strength of the position is modulated adaptively through noise visibility function (NVF), which is the best strength to ensure good visual effect of masking to achieve the best effect between robustness and imperceptibility. A large amount of experiments show that the proposed algorithm is effective and robust to common image processing operations.