块截断编码的图像自嵌入半脆弱水印算法  

Image self-embedding semi-fragile watermarking algorithm based on block truncation coding

作　　者：王艺龙 李震宇 巩道福 马世鑫 刘粉林 Wang Yilong;Li Zhenyu;Gong Daofu;Ma Shixin;Liu Fenlin(PLA Strategic Support Force Information Engineering University,Zhengzhou 450000,China;National Defense University of People’s Liberation Army(PLA),Beijing 100091,China)

机构地区：[1]中国人民解放军战略支援部队信息工程大学,郑州450000 [2]中国人民解放军国防大学,北京100091

出　　处：《中国图象图形学报》2022年第1期203-214,共12页Journal of Image and Graphics

基　　金：国家自然科学基金项目(U1736214,61772549)。

摘　　要：目的数字图像自嵌入水印技术是解决图像篡改检测和恢复问题的主要技术手段之一,现有的自嵌入水印技术存在着认证粒度不高、嵌入水印后的图像失真较大,且无法抵抗滤波等操作。为提高图像自嵌入水印的认证粒度以及抵抗滤波等处理操作的能力,提出了一种基于块截断编码的图像自嵌入半脆弱水印算法。方法水印生成与嵌入:首先,将图像进行块级别的二级划分,分别生成粒度为4×4和2×2的图像块;然后,利用块截断编码对每个4×4图像块进行压缩编码,生成2×2图像块的恢复水印,并对恢复水印进行哈希生成2×2图像块的认证水印;最后,将恢复水印和认证水印级联构成自嵌入水印,嵌入到映射块中。篡改认证与恢复:首先,将某个4×4图像块提取的水印与该块生成的水印比较,判别该图像块的2×2子块是否通过认证;最后,依据认证结果对2×2图像块实施恢复。结果该算法产生的水印图像的峰值信噪比(peak signal-to-noise ratio,PSNR)均高于44 dB,在50%的篡改率下,恢复后的图像质量可达到32.7 dB。该算法生成水印并在图像上嵌入大约需要3.15 s,恢复图像大约需要3.6 s。结论算法利用块截断编码,有效缩短了生成的水印长度,保证嵌入水印后图像的质量。此外,通过引入的可容忍修改阈值,使得水印能够对滤波等图像处理操作具有一定的鲁棒性,同时保证对图像的恶意篡改具有敏感性。最后通过与最近典型方法的对比实验,验证了算法在嵌入水印后图像质量、恢复图像质量等方面的优势。Objective Digital images have become the main interface for people to acquire and disseminate information.People can easily replace digital image content with fake to achieve a certain purpose via widespread availability of image processing and editing tools.Hence,it is one of the research hotspots in the field of information content security to judge the authenticity of the content of the digital image,and even restore the tampered area.Digital image self-embedding watermarking technology is one of the key technical implications constrained by low authentication accuracy and extremely quality loss without filtering.In order to improve the authentication accuracy and the resistance to filtering and other processing operations,a semi-fragile image self-embedding watermarking algorithm based on block truncation coding is proposed.Method 1)Watermarking generation and embedding:the image is divided into 4×4 image blocks,and each 4×4 image block is further divided into 2×2 image blocks.Then,block truncation coding is used to compress and encode each image block as the self-embedding watermarking information of the image block,and hash the self-embedding watermarking as the authentication watermarking information of the image block.At last,the self-embedded watermarking information and the authentication watermarking information form the watermarking information,which is embedded in the mapping block.2)Tampering detection and recovery:At the beginning,the authentication watermarking information of 4×4 blocks is compared to identify the tampering of the image block,and then set a threshold to determine the tampering of the 2×2 image blocks based on the block truncation coding information and restore it.The algorithm uses block truncation coding to effectively shorten the watermarking information generated for 4×4 image blocks.The watermarking information is just embedded in the lowest two bits of the pixel,the quality of the image is guaranteed following the embedded watermarking and 2×2 image targeted blocks bas

关 键 词：半脆弱水印 自嵌入 块截断编码 篡改认证 篡改恢复 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]