Application Of Fractional Fourier Transform In Digital Watermarking

Digital watermarking is a copyright protection technology of digital products appearing in recent years. It solves problems of information security and copyright protection by embedding invisible information into digital information products to identify their owners. The current digital watermarking algorithm has been divided into two types by spatial and frequency domain. Its ability to resist the attack is not yet satisfactory, but also it's difficult to achieve balance between many performances.In this paper, using good time-frequency domain characteristics of fractional Fourier transform, digital watermarking algorithms based on fractional Fourier transform are designed. The digital watermark is embedded into the original image by evenly distributed watermarking algorithm. We simulate the algorithm and analyze the robustness of watermark image under a variety of attacks, such as image rotation, clipping, PJEG compression and Gaussian noise. Experiments show that the algorithm has good robustness. Chapter VI presents a watermarking algorithm based on spatial domain and fractional Fourier domain. Watermark image is divided into two parts. One part is embedded into the space domain of the original image, and another part is embedded into the fractional Fourier domain. The watermarking algorithm has the following characteristics:the capacity of watermark increases as more digital watermark data is embedded into the original image; watermark has better robust and security; its ability to anti- attack and anti-handling is better.