结合DWT变换的二元纯位相滤波器水印

Binary phase-only filter based watermarking combined with discrete wavelet transform

提出了结合离散小波变换(discrete wavelet transform,DWT)的二元纯位相滤波器(binaryphase-only filter,BPOF)数字图像水印算法。首先对图像进行DWT变换,然后在DWT变换后的低频子带进行离散Fourier变换(discrete Fourier transform,DFT)变换,将DFT变换的相位信息二值化得到BPOF,并将其作为水印嵌入到相应的幅值中。与对图像整体进行DFT变换,并在其全频域或低频域嵌入BPOF水印相比,在保持嵌入水印的不可感知性和检测性能的同时,显著提高了抗JPEG压缩性能。该方法可用于图像真实性、完整性认证,仿真实验证明了算法的有效性。

The binary phase-only filter （BPOF） based digital image watermarking combined with a discrete wavelet transform （DWT） was proposed. Firstly, the DWT transform was applied to an image. Then, the discrete Fourier transform （DFT） was applied to the low frequency subband of the DWT transform. Next, the phase information of the DFT was binarized to obtain the BPOF, which would be taken as the watermark and embedded into the corresponding magnitude. Compared to applying the DFT transform to the whole image and embedding the BPOF watermark in the entire frequency range, or in the low frequency range, the watermark robustness in JPEG compression is improved significantly while maintaining the watermark imperceptibility and detection efficiency. This method may be used to demonstrate the authenticity and integrity of an image. The simulation experiments demonstrate the efficiency of this method.