基于二元纯位相滤波器水印的图像篡改定位

Image tampering localization based on binary phase-only filter watermarking

二元纯位相滤波器(BPOF)数字图像水印算法将图像离散Fourier变换的BPOF作为水印嵌入到其相应幅值的某个位平面中,较好地实现了图像自认证。研究了利用BPOF水印实现图像篡改定位。其基本原理是将图像划分为互不重叠的分块,通过在各分块中独立嵌入和检测水印,实现图像篡改检测和定位。着重讨论了以不同大小对于图像分块和以不同幅值位平面嵌入水印时,所嵌入水印的不可感知性、检测性能、图像篡改定位能力以及抗JPEG压缩性能。得出了图像分块大小、嵌入水印的幅值位平面及水印检测阈值等参数的选取策略。实验结果证明了BPOF水印可以很好地应用于图像篡改定位。

The Binary Phase-Only Filter （BPOF） digital image watermarking embeds the BPOF of the Discrete Fourier Transform （DFT） of an image into one of the bit planes of the corresponding magnitude for image authentication. In this paper, BPOF watermarking based image tampering localization was studied. To detect and localize the tampered regions in an image, the image was divided into non-overlapping blocks, while the watermarks were embedded and detected within the blocks individually. The discussion focused on the imperceptibility, the detection performance, the robustness to the JPEG compression of the embedded watermark and the image tampering localization ability, under different sizes of the image blocks and different magnitude bit planes for watermark embedding. The methods of selecting the sizes of the image blocks, the magnitude bit planes for watermark embedding, and the threshold values for watermark detection were obtained. The experimental results show that the BPOF watermarking can be used for image tampering localization.