基于图像校正的抗几何变换全息水印算法

目的提出了一种基于图像校正的抗几何变换全息水印算法。方法在水印嵌入时,将原始二值水印图像,利用共轭对称延拓傅里叶计算全息方法生成全息水印,并嵌入在原始图像小波变换的对角线高频系数中,逆变换得到含水印图像。在含水印图像的DFT域中嵌入模版信息,在水印提取时,首先利用模版信息对图像进行校正,然后提取水印信息。结果该算法保留了全息水印的优良特性,结合了模版匹配校正技术,可以有效抵抗滤波、噪声、裁切、JPEG压缩、旋转、等比例缩放及其组合攻击。结论该算法在实际应用中能有效抵抗几何攻击,可以应用于数字图像的版权保护中。

Holographic Watermarking Algorithm Resistant to Geometric Attack Based on Image Correction

Objective To propose a holographic watermarking algorithm resistant to geometric attack based on image correction. Methods In the phase of watermark embedding, a binary watermark was converted to a hologram using the computer generated holography by the conjugate-symmetric extension, and the hologram was embedded in the high-frequency coefficients of the original image decomposed by DWT transformation. The template was then inserted into the DFT domain of the watermarked image. During extraction of the watermark, the image was first corrected using the template information and then the information was extracted. Results The proposed algorithm combined the use of holography and the image correction method of template matching. It could effectively resist low-pass filtering, noise, cropping, JPEG compression, rotation, scaling attacks and hybrid attack of rotation and scaling. Conclusion The algorithm proposed in this paper could efficiently resist geometric attacks in practice and could be used in copyright protection.