针对传统数字图像水印版权保护中存在的鲁棒性差和安全性低的问题, 为提升不同图像零水印的可区分性, 提出了一种基于多特征和混沌加密的零水印算法. 首先根据整体与局部的角度提取图像的5维特征: 均值特征、方差特征、偏态特征、峰度特征和HOG特征; 然后利用新提出的基于混沌映射的块置乱方法加密水印图像; 最后基于提取的多特征与置乱后水印, 构造零水印信息. 在版权认证过程中, 首先提取多特征, 再结合零水印信息, 得到加密后水印; 最后对其进行解密; 即可实现版权认证. 实验结果表明, 所提出的方法效率高、安全性高、抗攻击能力强. 基于多特征和混沌加密零水印算法综合了数字图像的多方面性质作为特征, 稳定性高, 提高了算法鲁棒性; 同时采用新提出的基于混沌映射的块置乱方法提高了水印图像安全性, 有效地解决了图像水印鲁棒性差和安全性低的问题.
Given the poor robustness and low security of traditional watermark-based copyright protection of digital images, a zero watermarking algorithm based on multiple features and chaotic encryption is proposed to improve the differentiability of the zero watermarks of different images. Specifically, global and local perspectives are utilized to extract the five-dimensional features of the image, including its mean feature, variance feature, skewness feature, kurtosis feature, and histogram of oriented gradients (HOG) feature. Then, the watermarked image is encrypted by the proposed block scrambling method based on chaotic mapping. Finally, zero watermarking information is constructed with the multiple features extracted and the scrambled watermarks. The copyright authentication process starts by extracting the multiple features. Then, the encrypted watermarks are obtained according to the zero watermarking information and decrypted, thereby achieving copyright authentication. The experimental results show that the proposed method has high efficiency, high security, and strong anti-attack capability. Integrating various properties of the digital image as the features, the proposed zero watermarking algorithm based on multiple features and chaotic encryption is stable and more robust. In addition, the proposed block scrambling method based on chaotic mapping improves the security of the watermarked images. The proposed algorithm and method effectively solve the problems of the poor robustness and low security of image watermarks.