  In this paper, a robust blind image watermarking method is proposed for
copyright protection of digital images. This hybrid method relies on combining
two well-known transforms that are the discrete Fourier transform (DFT) and the
discrete cosine transform (DCT). The motivation behind this combination is to
enhance the imperceptibility and the robustness. The imperceptibility
requirement is achieved by using magnitudes of DFT coefficients while the
robustness improvement is ensured by applying DCT to the DFT coefficients
magnitude. The watermark is embedded by modifying the coefficients of the
middle band of the DCT using a secret key. The security of the proposed method
is enhanced by applying Arnold transform (AT) to the watermark before
embedding. Experiments were conducted on natural and textured images. Results
show that, compared with state-of-the-art methods, the proposed method is
robust to a wide range of attacks while preserving high imperceptibility.
