Abstract: This paper proposes a digital watermark algorithm resisting to geometric distortions. The max smooth area of the image is obtained according to the results of edges detection and the entropies of the image’s blocks, and the histogram of the area is equalized via exact histogram specification approach to the desired shape. In order to improve the accuracy of watermark detection and the fidelity degree of the image watermark embedded in, the serrate shape is utilized as the digital watermark. Experimental results show that the algorithm yields high fidelity degree and relatively high robustness to geometric distortions, and it obtains high tolerance to several signal processing approaches including linear filtering, nonlinear filtering, the addition of Gaussian noise, the addition of salt-and pepper noise and JPEG compression.

Key words: digital watermark, geometric attack, histogram specification

摘要： 提出一种基于严格直方图规定化的抗几何攻击数字水印算法。该算法基于图像块信息熵与边缘检测结果，选择图像最大的平坦区域，利用严格直方图规定化将图像平坦区域的直方图规定化为特定形状，为了提高水印检测精度与嵌入图像的保真度，选择锯齿状直方图作为水印信息。实验表明，该算法嵌入水印后的图像具有很好的保真度，对几何攻击、噪声污染、JPEG压缩、线性和非线性滤波有较好的鲁棒性。

关键词: 数字水印, 几何攻击, 直方图规定化

CLC Number: 

• TP391