说明：  no intro
(Blind watermark extraction can be fulfilled without referring to the original host image. Therefore it hasmuch prospective applications in the fields of information hiding and copyright protection. Based on blocking Discrete Cosine Transform (DCT) and blocking DiscreteWaveletTransform (DWT), the proposed blind watermarking algorithm uses an embedding strategy of adaptively selecting either relationship embedding or quantization embedding. The relationship em- bedding comes from the observation thatboth themagnitudes of coefficients concerned in the relationship usually have thesame change trend when the image is attacked. This strategy remarkably improves the robustness ofwatermark extraction.In addition, dithermodulation is used in quantization embedding, bywhich the tradeoff between transparency and robus-tness ofwatermarking can be easily adjusted. Simulation results show that the algorithm is fairly robust against the attacks such as noise, filtering, compression, and contrast )