Research On Grar-Level Watermarking Of Color Image Based On Wavelets Transform

The multimedia technology has become more and more important along with the booming development of network and digital communication technology. Various kinds of digital multimedia information including text, image, audio and video etc., have widely been distributed through network. At the same time, how to protect this copyright of digital information has become a question need to solve at once. Digital watermarking as the copyright protection and contents authentication of digital media has become an effectual way. Digital watermarking may be a good way to resolve the issue, so it has become a hot research topic and has drawn extensive attention in the field of the information saved. However the practical techniques in color image digital watermarking is lesser studied, especially for the embedding algorithm of grayscale watermarking signal. Because of the question of the gray-level watermark need more places to embed complicate information .Thus, it becomes a challenging question that how to deal with the invisibility and robustness of the digital watermark.In this article, considering the characteristic of human visual system, three gray-level watermark of color image digital watermarking algorithms based on the optimum combine of the wavelet transform and other methods were presented according to the deal with the invisibility and robustness of the digital watermark .A digital watermarking algorithm based on bit decomposition and wavelet transform .The basic thought of this algorithm is makes wavelet transform to the carriers image ,and makes bit decomposition to the watermarking image ,then chose the important bits to enlarge frequent and embed in the part of the median frequency and the low frequency weight of the carriers image .At on time embed the unimportance bits in the median frequency weight ,then construct again have the color image of the watermarking.Also we groped a digital watermarking algorithm based on DCT compression and wavelet transform .It first make JPEG compression and code to the watermarking image and make wavelet transform to the carriers image. According to JND embed the in the carriers image.Another digital watermarking algorithm based on wavelet transform is proposed. It makes wavelet transform to the carriers image and the watermarking image, and make the low frequency weight of the watermarking image enlarge frequent ,then embed in the low frequency weigh of the carriers image. It makes the high frequency weight of the watermarking image embed in the median high frequency weight. In this article, we have that watermarking algorithm imitated and simulation test, the experimental results show that the proposed watermarking scheme is robust for various attacks such as noise adding, JPEG compression and cropping.