No abstract

This paper proposes a robust and blind watermarking algorithm based on matrix Singular Value Decomposition (SVD) perturbation theory for JPEG image copyright protection. First, the quantized DCT coefficient blocks are extracted from the JPEG image, then SVD is performed on each block, and finally the watermark is embedded into a set of selected maximum singular values of the quantized Discrete Cosine Transform (DCT) coefficients using dither modulation. From the embedding principle of the watermarking algorithm, we can see that the watermark information can be completely extracted correctly when the watermarked image under certain attack. A large number of experiments show that the algorithm has a higher degree of robustness against attacks such as Gaussian noise and JPEG compression, etc.

0XOWLEHDP VDWHOOLWH FRPPXQLFDWLRQV HPSOR\LQJ IXOO IUHTXHQF\ UHXVH KDYH WKH SRWHQWLDO WR LQFUHDVH VSHFWUDO HI¿FLHQF\However, they suffer from severe inter-beam interference. An expectation propagation based message passing algorithm is proposed for decoding multi-user transmissions in the reverse link of multi-beam satellite communications with full frequency reuse. Compared with an iterative MMSE (Minimum Mean Square Error) interference cancellation algorithm, the proposed algorithm reduces the cubic complexity to square complexity in the number of interfering beams. Numerical results show that the proposed algorithm outperforms the iterative MMSE algorithm slightly in terms of bit error rate when the energy per bit to noise power spectral density ratio is low. The performance of both algorithms is the same for other cases.