融合区域边缘特征的双重自适应图像水印算法  

Double adaptive image watermarking algorithm based on regional edge features

作　　者：郭娜 黄樱 牛保宁 兰方鹏 牛之贤 郜卓杰 GUO Na;HUANG Ying;NIU Baoning;LAN Fangpeng;NIU Zhixian;GAO Zhuojie(School of Information and Computer,Taiyuan University of Technology,Taiyuan 030026,China;School of Artificial Intelligence,Beijing University of Posts and Telecommunications,Beijing 100089,China;Institute of Automation,Chinese Academy of Sciences,Beijing 100190,China)

机构地区：[1]太原理工大学信息与计算机学院,山西太原030026 [2]北京邮电大学人工智能学院,北京100089 [3]中国科学院自动化研究所,北京100190

出　　处：《西安电子科技大学学报》2023年第5期118-131,共14页Journal of Xidian University

基　　金：国家重点研发计划(2021YFF0900100);山西省重点研发计划(20210201010100)。

摘　　要：局部图像水印技术是指在图像的部分区域而非完整图像中嵌入水印,可抵抗裁剪类攻击,是目前水印领域的研究热点。当图像被攻击后,现有局部水印技术通过特征点定位的水印嵌入区域可能发生偏移,当区域中包含较多边缘时,由于边缘附近像素值差异明显,定位偏移会导致区域整体像素值发生较大的变化,使得水印提取失败。针对该问题,提出融合区域边缘特征的双重自适应图像水印算法。首先,提出一种嵌入区域的判定方法,利用滑动窗口遍历图像,综合边缘、纹理、灰度、位置等因素,对窗口区域进行评分,选择出含边缘少且隐藏性好的区域作为水印的嵌入区域。其次,提出一种双重自适应嵌入方案。在水印嵌入时,通常需要对图像进行分块,通过修改像素值,在一个图像块中嵌入1位水印信息。第一重粗粒度自适应方案是指通过线性回归分析,建立用于控制水印嵌入强度的参数和图像块边缘像素数量间的函数关系,根据不同图像块的特点自适应调节对应的水印嵌入强度,增强包含边缘图像块嵌入水印的鲁棒性;第二重细粒度自适应方案是指在修改像素时,区分对待图像块中的边缘处像素和非边缘处像素,利用高斯窗自适应地调整边缘附近像素的修改量以达到平滑过渡的效果,利用边缘的掩蔽效应提升水印的不可见性。实验证明,该算法相比于已有自适应图像水印算法有更好的不可见性及更强的鲁棒性。Local image watermarking is a hotspot technology which embeds watermark in a partial image and can resist cropping attacks.Existing local watermarking technology locates the embedded region by the feature points,which may be offset when attacks occur.Due to the obvious difference of the pixel near edges,if the region contains many edges,the offset will lead to excessive regional pixel error and fail the watermark extraction.To solve this problem,a double adaptive image watermarking algorithm based on regional edge features is proposed.First,a method to determine the embedding region is proposed,which uses a sliding window to choose embedding regions with few edges and good hiding ability by taking image features such as the edge,texture,etc.into account.Second,a double adaptive watermark embedding scheme is proposed,which is divided into blocks,with each block embedding 1-bit watermark information by modifying the pixel value.In the first coarse-grained adaptive scheme,the function between the embedding parameter and the number of edge pixels is established through linear regression analysis,and the embedding strength is adaptively adjusted by the function to enhance the robustness of blocks containing edges.In the second fine-grained adaptive scheme,the gaussian window is used to adaptively adjust the modifications of different pixels to improve the imperceptibility of the watermark.Experiments show that the proposed algorithm can effectively enhance the robustness of the watermark at the edge,and improve its imperceptibility.

关 键 词：图像水印 边缘特征 不可见性 鲁棒性 自适应 

分 类 号：TP309.7[自动化与计算机技术—计算机系统结构]