A Research Of Ditial Watermarking Technique Based On DWT Domain

A digital watermark is an invisible mark embedded in digital images, video or audio documents, which can be used for a number of different purposes including copyright protection, authentication and captioning.According to the human visual system (HVS), two watermark embedding algorithm is proposed employing the characteristics of multi-resolution analysis of the two-dimension discrete wavelet transform (DWT).One method is to embed the watermarking signal of pseudo-Gauss random sequence into the low frequency sub band of DWT domain by analyzing both the distribution of the signal energy and the influence of the image disposal. We also study the embedding formula and the coefficients selection of DWT domain for consummates the watermarking arithmetic. The other method is to embed a grayscale image watermarking (which involves the copyright message) into a color image through considered from the practical application. In this arithmetic, we embed the watermark into the DWT coefficients of color image luminance (Y) component, so that the color of original image will not be affected. We also employ the multiresolution fusion techniques of the image and adopt the divided method for repeat embeds. Moreover, in order to raise the watermark's security and keep resilience to cropping attack, we used the magic square shuffling techniques in watermark image before embed the mark.Finally, in order to test the imperceptibility and robustness of the two improved algorithms, a lot of experiments were done. The experimental results show that the watermarks generated with the proposed algorithm are invisible and robust against noise and commonly used image-processing technique.The research and experiment results in this paper have important reference value both in further studying digital watermark and in developing computer software concerned.