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A grayscle watermarking blind algorithm resistant to geometric attacks based on the lifting wavelet transform

To address the technical problem that hinders the practical application of digital watermarks, an implementation method of digital watermarking against the geometric attacks with the lifting wavelet transform (LWT) is proposed. Based on the characteristics of the wavelet transform sub-bands, one of the wavelet sub-bands of the carrier image is divided into four blocks. This method is combined with the uniform log-polar mapping. The watermark informations are embedded into the designated spectrum coefficients of the carrier image by setting a relevant parameters. The rotation angle estimation method based on Fourier logarithmic transformation with high precision and high speed is proposed. Compared with the existing watermark methods, the simulation results show that the robustness of the proposed watermark method against the geometric attacks significantly improved.