Research Of Digital Watermarking Technique Based On Wavelet Transform

Nowadays, with the rapid development of the digital and networks technologies information security is becoming more and more important coupled. Watermark is a process of embedding a special signal called watermark into digital products to prove their copyright. Digital watermark provides a new valid solution to the copyright protection. The digital watermark technology is becoming a hot issue in the field of information security, due to its application in copyright protection. Digital watermark technology has drawn extensive attention in recent years. But, there is still a lot of work need to be done. Therefore, this paper is of research value and practical significance.Now, most of the watermark algorithms hide the random signal or two-value image into the image, only a few watermark algorithms hide the gray-level and RGB image into the image. In my dissertation, we put forward the algorithm to try this technology and study watermark by wavelet transform in the frequency domain. The research work in this dissertation is mainly on invisible watermark. Two kinds of algorithm were brought forward.A kind of algorithm that is digital watermarking technique for color image based on DWT and bit expand. Firstly, to ensure the security of wartermark,the wartermark image is Arnold scrambled before embedding and expanded to the twifold size of the original image.The corresponding subband data of the watermark and the red,green,blue weight for original image are combined according to the characteristic of the multiresolution decomposition of the wavelet transform.Another kind of algorithm is a self_adaptive digital watermarking technique base on integer wavelet transform.The arithmetic is for gray-level images watermark. First of all, the original image and the image watermark that is encrypted by magic square transform is decomposed by the method of a integer wavelet,and the low frequency part of the watermark decomposed into eight binary bit-planes. Then an approach for transparent image watermark based on integer wavelet is proposed in which eight binary bit-planes is embedded in the original image.The method uses the characteristic of Human Visual System(HVS) to adjust the intensity of the watermark adaptively.A embed place matrix is set to record information about embedding watermark and be used for blind detecting the watermark.