Dual Digital Watermarking Algorithm for Image Based on Fractional Fourier Transform

In this paper, a dual digital watermarking embedding and detecting algorithm for image is presented, which uses the robust watermark and fragile watermark embed in the fractional Fourier transform (FRFT) domain of the image, and the watermark position and the transform order are used as the encryption keys. The experiment results show that the embedded watermark is perceptually invisible and robust to various image processing operations. Most importantly, the tampered place can be identified accurately.