Abstract: The binary phase-only filter digital watermarking embeds the phase information of the discrete Fourier transform of an image into the corresponding magnitude for image authentication.In the paper，embedding the BPOF watermark by quantizing the magnitude is studied.Adjusting the quantization steps following the frequencies of the magnitude coefficients，and embedding the watermark into the low frequencies are discussed.Theoretical analysis and experimental results show that，with quantization based watermark embedding，the flexibility，security，watermark imperceptibility and detection performance are improved effectively，while the robustness against JPEG compression is enhanced at a certain degree.

摘要： 二元纯位相滤波器数字图像水印算法将图像离散Fourier变换的相位信息作为水印嵌入到其相应的幅值中，较好地实现了图像自认证。研究了通过量化幅值实现水印嵌入，讨论了根据嵌入水印的各幅值系数所处的频率位置调整量化步长，以及在低频域量化嵌入水印。理论分析和实验结果表明，通过量化幅值嵌入水印，可有效改进算法的灵活性、安全性、水印不可感知性和检测有效性，并且在一定程度上提高了抗JPEG压缩性能。