Research On Digital Image Watermarking Based On Fourier Transform And Synchronization Template

With the rapid evolvement of multimedia technology and network communication,digital products become more and more convenient to modify,duplicate and transmit.Meanwhile,such products are also susceptible to the malicious attack,which is a great threat to the security and integrity of the digital products.How to protect the copyright of the multimedia digital products has attracted more and more attention.Digital watermarking as a kind of information hiding has been proved to be an effective approach to solve such problem.There are four main requirements in designing a watermark system,the capacity,the invisibility,the robustness and the security.Besides the invisibility and the robustness are the current researching hotspots.The method proposed in this paper is based on Fourier transform and synchronization mark,which tries to design a more invisible and robust watermarking scheme.The process can be described as follows: the watermark is generated by the chaotic system;the watermark is first embedded in the real part of the Fourier domain of the original image and afterwards the synchronization mark is embedded in the imaginary part.In addition,the original image is not required in the detecting process,which increases the applicability of the watermarking system.PSNR will be used to evaluate the quality of the watermarked image and the normalized cross correlation will be used to compute the similarity of the extracted watermark and the original watermark.The experiments show that the method has a decent performance of invisibility and robustness,especially against the cropping attack and the sharpening attack.Besides,it can resist small limits of rotation.