An NPT Watermarking Algorithm Using Wavelet Image Combination

In order to eliminate the artifacts caused by transform in NPT watermarking algorithm effectively, we applied the wavelet image fusion to the algorithm based on discrete cosine transform. The quality of the watermarked image is improved remarkably. However, the noise introduced by image combination degrades the constructed watermark. To deal with it, we performed a pre-process of de-noise before extracting watermark. Experimental results show that the algorithm has a good robustness against JPEG compression, geometric attacks and noises.