A new watermarking algorithm based on NSCT_DCT is proposed to improve the robustness of digital watermarking. This algorithm performs L-level NSCT transformation on the image which requires to be embedded watermark, and DCT transforms the low frequency band. The DCT coefficients are chosen as the feature of the image, which are unchanged or changed after the geometric transformation. XOR and scrambling the watermark using image features, get a key. Complete the extraction process by the secret key. Simulation results show that the proposed algorithm is robust to common Gaussian noise, salt and pepper noise and mean filtering. It is also resistant to rotation, aspect ratio variation and shear geometric transformation, which are difficult to be resisted for most watermarks.
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