Application Of Chaotic Map In Digital Image Watermarking Scheme

As the rapid growth of Internet and digital technique, varies kinds of media digital works can be obtained in Internet. The convenient and non-security of the digital works exist at the same time. The digital works can be copied and transmitted easily and low cost, it offers great benefit for the author and user, but the pirate can also utilize such character. So taking measures to protect digital works and punishing the pirate are exigent now. Beside the instruments of law and supervise, we should provide technique protects based on digital works specialties. How to carry copyright protection and insure the infonnation security is the nuclear issue in era property protection. The technique of Digital Watermarking is developing on such appliance request and turns into the pop task.Based on the research of status quo of Digital Watermarking and other schemes, this paper presents a new scheme in DCT (Discrete Cosine Transform) and analyzes the embedding method and chaotic encryption expressly. Such new embedding and extraction arithmetic are based on modular operation. Applying topic image processing operations to the marked image, the experiments results show that: such scheme is robust against cropping and noise disturbance. As for the JPEG compression, the extracted watermark is not intact. At the same time, the larger the modular is the poorer the transparence of the scheme is, and the extracted watermark from the marked image is clearer. To enhance the security and random of the proposed scheme chaos map is applied. Chaotic sequence is simple and hypersensitive to the original value, and the orbit is incertitude. Such characters are right for the encryption of the watermarking. The proposed scheme uses chaotic sequence twice: first to disorder the original mark;second to select the modified DCT blocks. Simulation results prove that the correlation coefficient between the disordered and the original mark is small.This paper also presents a watermarking scheme based on DWT (Discrete Wavelet Transform). Within recent years, increasingly DWT has been used in many real applications. DWT has favorable frequency character and the multiplayer decompose analyses is identical with human's vision custom, such is special useful for selecting embedding position and intension in Digital Watermarking. First applying three scalesDWT to the host image. For visual imperceptiveness and robustness purpose select the vertical and horizontal detail weight in middle frequency domain to carry mark. The embedding arithmetic is based on addition principle. Chaotic map determines which pixels to be modified. Simulation results show that such scheme is good at transparence and robust against cropping, filter, noise disturbance and so on. Especially for JPEG compression, clear mark can be still extracted from the compressed watermarked image even there is great degradation in watermarked image.