The Research Of Binary Images Blind Watermarking Based On Wavelet

With the rapid development of computer network and multimedia technology, a fine protection of digital multimedia copyright became a desideratum for the customers. As one of the important applications of information hiding field, digital watermarking provides a new method to protect the copyright of multimedia information, and ensures the multimedia products are used legally. It embeds watermarks into digital multimedia, and carries out the functions such as information hiding, secret storing, and copyright protection by detecting the watermarks that can track the use of digital multimedia.With the receiving of binary images multimedia products, digital watermarking has been proposed as a solution to the problem of copyright protection. Many digital watermarking techniques have been proposed for digital color or gray images; however most of them cannot be directly applied to binary images. The difficulty consists in the fact that changing pixel values in a binary image can cause irregularities that are very visually noticeable.This paper takes binary images as example, and introduces basic theory, character and application of image watermarking. The typical algorithm and performance evaluation methods of watermarking are analyzed. The wavelet transform theory and its application in watermarking are also explained. This paper researches on some important topics such as the selection of watermark information, preprocess methods of watermark, choosing of wavelet bases and decomposing level and positions for embedding watermark. To solve the contradiction between robustness and imperceptibility of watermarking and the problem of blind detection, a blind digital watermarking algorithm based on wavelet transform is presented. In this paper the main contributions in this paper are as follows:1. This paper selects a significative binary image as watermark. The watermark is pre-processed. By scrambling, the watermark becomes disorderly and unsystematic. On the one hand it can avoid attacking the watermark system, and enhance the security of the watermark system. On the other hand it makes the watermark image to disperse the error bit information possibly when the image, which contains the watermark, is destroyed.2. Research on embedding strategy and algorithm in wavelet domain. Taking advantage of the features of human visual system (HVS), with the sensitivity of human eye towards local brightness and texture intensity, the quantification coefficient can be selected by splitting the difference to solve the contradiction between robustness and imperceptibility of watermarking.3. In order to ensure the image embedded the watermark is still a binary image, it should be binaried. This paper uses a global threshold. Experimental results demonstrate that the global threshold can ensure the watermark exists after binarization.4. This algorithm does not need the primitive image in the watermark recovery, has realized the blind detection, and is advantageous in the protection primitive image security.Experimental results demonstrate that this watermark system has well invisibility and security, and its robustness is very well for the familiar image processed.