Research of a Digital Image Watermarking Algorithm Resisting Geometrical Attacks in Fourier Domain

A digital image watermarking algorithm based on Fourier domain is proposed. This algorithm calculates an Invariant Centroid of the image and uses it as the origin of logarithm polar mapping (LPM). Then two-dimensional Discrete Fourier Transform (DFT) is performed on the LPM image. And then the amplitude of intermediate frequency is used as the watermarking embedding domain. In order to enhance the safety of the algorithm, it is necessary to encrypt the watermarking signal with the key K, then carry out BCH code on the encrypted signal in order to enhance robustness of resisting various attacks of this algorithm. Therefore the algorithm has a promising prospect of wide use in the fields of the copyright protection of the digital image etc.