The Research Of Binary Text Image Digital Watermarking

Digital watermarking is a type of effective copyright protection technology. Currently, most of digital watermarking research are focused on color images, audio, and video .Because of the particularity of binary image, especially binary text images, there are few works have been done about this kind of still image. In fact, lots of important documents ,such as digital book, archives, are kept in binary image form ,they also need copyright protection.We first analyzed the representative digital watermarking schemes about binary images and introduce a novel watermarking scheme for binary images according to an architectural feature of Chinese characters and DRDM measure. The emulation experiment results of Matlab shows that the new watermarking method has good robustness to JPEG compression and has a certain robustness on Gaussian noise, salt & pepper noise.In addition ,we compared several kinds of popular binary image distortion standards and point out that the most effective method ,which named DRDM, has a drawback when compute the distortion of binary Chinese character images. In order to solve the problem ,we use m×n,m≠n matrix as weighting matrix, instead of n × n weighting matrix which used by DRDM. The validity of this modification can be verified by calculating the smoothness of pixels and their neighborhood.