基于自适应图像块组合的无损图像认证算法

现有基于分块的无损图像认证算法在图像认证块划分方面存在不足。为此,提出一种基于自适应分块组合的无损图像认证算法。算法中的认证块由基本分块根据原图像特征和水印图像保真度要求自适应组合而成,认证信息用数字签名技术产生,以无损水印方式嵌入,同时以多次嵌入方式实现图像编号的顽健传送,利用图像编号和认证块编号防止矢量量化攻击。理论分析与实验结果表明该算法篡改定位能力强于现有无损图像认证算法,且适应性强,能抗矢量量化攻击。     

基于子块区域分割和自嵌入技术的全盲多功能图像水印算法

利用子块区域分割思想和自嵌入技术提出了一种只利用攻击图像就能进行版权鉴别和内容认证的全盲多功能图像水印算法。将原始图像分割成不重叠的子块,对每个子块进行离散余弦变换,将每个子块离散余弦变换矩阵分成为区域1和区域2两部分,然后对区域1进行奇异值分解,通过判断奇异值均值的最高位数字奇偶性产生特征水印,然后通过调整区域2的2个离散余弦变换交流系数大小自嵌入特征水印,最后对每个子块进行逆离散余弦变换得到含水印图像。算法通过结合将区域1产生的特征水印自嵌入区域2和在区域2盲提取认证水印实现全盲检测和多功能。实验结果表明,算法既能实现版权保护又能实现内容认证,而且还具有区分恶意篡改和无意篡改的能力。     

基于ROI的图像检索算法研究

针对全局特征的图像检索不能很好地满足用户的意图和基于图像分割的检索过分依赖复杂的图像分割算法二者的不足。在基于子图的检索思想的基础上，给出了一种基于用户感兴趣区域的图像检索算法。该算法无需对图像进行复杂的分割就能提取对象特征，实验证明该算法具有简单、高效、查全率较高的优点。     

改进型遗传算法在医学图像分割中的应用

医学图像分割是图像分割领域的重要分支,文章研究了基本遗传算法和改进型遗传算法在医学图像分割中的优劣,通过引入两个经典测试函数对两种算法进行了仿真对比,实验结果表明,改进后的算法可以有效地提取感兴趣的图像区域,具有较好的寻优能力。     

基于多阈值分割的红外与可见光图像融合

对基于NSCT分解的可见光和红外图像的融合算法进行了优化技术研究.在场景复杂或有多个区域需要同时关注时,低频子图融合阶段采用简单的二值化区域分割方法并不能将不同区域的感兴趣目标有效地反映到融合结果中.所以本文采用基于最大熵的多阈值分割方法,并对每一个分割区域计算其区域能量比指导融合系数的求取;高频融合阶段采用最能保持图像细节的梯度最大规则.实验结果表明本文算法能够将多个区域中的感兴趣目标很好地反映到融合结果中,并保留了可见光图像丰富的细节信息和分辨率高特征,融合图像具有更好的视觉效果.     

一种快速鲁棒的红外图像分割方法

介绍了一种快速鲁棒的红外图像分割方法,算法是为了满足工程化应用。首先采用Canny边缘检测算子提取图像的边缘像素;然后统计边缘像素灰度值得到红外行人图像的分割阈值,并利用自适应双阈值算法对图像进行初始分割;最后通过边缘扫描对初始分割的图像区域进行边界修正,得到边界更加精确的目标区域。实验结果表明,该方法能够较好地保留行人的边缘信息,减少了区域像素错误分割,且具有较强的实时性。     

医学图像中典型分割算法的比较分析

通过图像分割算法获取医学图像感兴趣区域是医学图像分析与识别要解决的首要问题及技术难点。在阐述医学图像分割及其研究意义的基础上,总结了医学图像分割中的典型算法。接着,以MR颅脑图像的分割为例,做了基于FCM、C-V、区域生长法的图像分割及对比分析,讨论了医学图像有效分割存在的技术难点。最后,指明了医学图像分割未来的发展趋势。研究成果对深入认识医学图像分割的研究意义、分割算法、分割难点、分割趋势等,推动医学图像分割技术的发展均具有一定意义。     

面向医学图像的篡改检测双重水印算法

针对医学图像中嵌入水印信息造成的鲁棒性与透明性的不平衡问题，提出了一种面向医学图像的篡改检测双重水印算法。首先，采用Sine-Cubic混沌映射加密算法将Sine映射与Cubic映射进行线性耦合，利用得到的混沌序列对版权图像进行加密。其次，对载体图像进行小波变换，并对低频子带进行安全区域划分，根据安全区域内子块熵值将医学图像划分为感兴趣区域（ROI）和非感兴趣区域（NROI）。同时，通过提取ROI的稳定特征与加密的版权构造鲁棒的零水印。最后，将零水印嵌入医学图像NROI子块Schur分解的上三角矩阵最大系数中，同时记录嵌入水印后的最大系数用于篡改检测。实验结果表明：所提水印算法具有不可感知性、鲁棒性和安全性，同时可以准确地定位被篡改的含水印区域；与其他水印算法相比，所提双重水印算法在鲁棒性和算法效率上均有很大的提升。     

一种改进的一维模糊熵图像分割算法

传统的一维最大模糊熵图像分割算法对于图像的局部信息干扰噪声处理能力存在不足。文中研究实数编码混沌量子遗传算法（RCQGA）与一维模糊熵算法相结合的新算法。该算法将图像的空间信息和像素信息引入到一维模糊熵图像分割算法中,并运用实数编码混沌量子遗传算法对一维最大模糊熵图像分割算法进行改进,从而提高了一维最大模糊熵分割精度。研究结果表明,该算法分割效果明显优于传统一维模糊熵图像分割算法,并具有较强的抗噪性能。     

基于红外CCD的掺钆液体闪烁体液位测量方法

图像分割在医学超声图像的定量、定性分析中均扮演着十分重要的作用, 并直接影响到后续的分析、处理工作。针对医学超声图像对比度低和噪声强的特点, 提出了一种将超像素和模糊聚类技术相结合的图像分割方法。该方法利用简单线性迭代聚类算法产生多个超像素子区域, 通过比较各个子区域间特征向量的相似性, 利用模糊C均值(FCM)聚类技术对这些过分割区域进行合并, 实现超声图像目标区域的有效分割。和传统的基于单像素的FCM聚类算法相比, 该方法具有较强的鲁棒性, 有效提高了目标区域的分割精度和分割效率, 取得了较好的分割效果。     

Semi-fragile watermarking algorithm for image tampers localization and recovery

Two watermarks are embedded into the original image. One is the authentication watermark generated by secret key, which is embedded into the sub-LSB （Least Significant Bit） of the original image for tamper localization; the other is the recovery watermark for tamper recovering. The original image is divided into 8 x 8 blocks and each block is transformed by Discrete Cosine Transform （DCT）. For each block, some lower frequency DCT coefficients are chosen to be quantized and binary encoded so as to gain the recovery watermark of each block, and the recovery watermark is embedded into the LSB of another block by chaos encryption and authentication chain technology. After the two watermarks being detected, the location of any minute changes in image can be detected, and the tampered image data can be recovered effectively. In the paper, the number of coefficients and their bit lengths are carefully chosen in order to satisfy with the payload of each block and gain the capability of self-recovering. The proposed algorithm can well resist against possible forged attacks. Experimental results show that the watermark generated by the proposed algorithm is sensitive to tiny changes in images, and it has higher accuracy of tamper localization and good capability of the tamper recovery.     

Robust digital signature for multimedia authentication

Image authentication verifies the originality of an image by detecting malicious manipulations. This goal is different from that of image watermarking which embeds into the image a signature surviving most manipulations. Most existing methods for image authentication treat all types of manipulation equally (i.e., as unacceptable). However, some applications demand techniques that can distinguish acceptable manipulations (e.g., compression) from malicious ones. In this paper, we describe an effective technique for image authentication, which can prevent malicious manipulations but allow JPEG lossy compression. The authentication signature is based on the invariance of the relationship between the DCT coefficients at the same position in separate blocks of an image. This relationship will be preserved when these coefficients are quantized in a JPEG compression process. Our proposed method can distinguish malicious manipulations from JPEG lossy compression regardless of how high the compression ratio is. We also show that, in different practical cases, the design of the authenticator depends on the number of recompression times, and whether the image is decoded into integral values in the pixel domain during the recompression process. Theoretical and experimental results indicate that this technique is effective for image authentication.     

Identification of inpainted images and natural images for digital forensics

Image forensics is a form of image analysis for finding out the condition of an image in the complete absence of any digital watermark or signature.It can be used to authenticate digital images and identify their sources.While the technology of exemplar-based inpainting provides an approach to remove objects from an image and play visual tricks.In this paper,as a first attempt,a method based on zero-connectivity feature and fuzzy membership is proposed to discriminate natural images from inpainted images.Firstly,zero-connectivity labeling is applied on block pairs to yield matching degree feature of all blocks in the region of suspicious,then the fuzzy memberships are computed and the tampered regions are identified by a cut set.Experimental results demonstrate the effectiveness of our method in detecting inpainted images.     

Multimedia Broadcast Authentication Based on Batch Signature [Advances in Mobile Multimedia]

Conventional block-based broadcast authentication protocols overlook the heterogeneity of receivers in mobile computing by letting the sender choose the block size, divide a broadcast stream into blocks, associate each block with a signature, and spread the effect of the signature across all the packets in the block through hash or coding algorithms. They suffer from some drawbacks. First, they require that the entire block with its signature be collected before authenticating every packet in the block. This authentication latency can lead to the jitter effect on real-time applications at receivers. Second, the block-based approach is vulnerable to packet loss in mobile computing in the sense that the loss of some packets makes the other packets unable to be authenticated, especially when the block signature is lost. Third, they are also vulnerable to DoS attacks caused by the injection of forged packets. In this article we propose a novel broadcast authentication protocol based on an efficient cryptographic primitive called a batch signature. Our protocol supports the verification of the authenticity of any number of packets simultaneously and avoids the shortcomings of the block-based approach.     

双重功能图像水印算法

提出一种能同时实现内容认证和版权保护双重功能的图像水印算法.首先,对原始图像进行分块奇异值分解(SVD),计算所有子块最大奇异值的均值,通过比较各子块的最大奇异值与所有子块最大奇异值的均值间的数值关系产生鲁棒零水印序列.然后,对原始图像进行分块离散余弦变换(DCT).调整图像子块DCT高频系数的数值大小,建立同一子块两...     

基于色调处理技术的图像认证算法

基于色调处理技术,该文给出了一种有效可行且具有自修复能力的图像认证算法。首先,基于误差扩散色调处理技术将水印图像4bit色调量化,井依据混沌置乱算子,将色调结果置乱,然后构造平均误差最小的特征集合C,最后依据误差扩散数据隐藏算法将置乱后水印图像隐藏于原始图像中;在认证端,从接收到的图像提取其中所隐藏水印信息并进行逆置乱,比较接收到的图像和反置乱后的隐藏信息,判断内容发生变化的位置,并依据所提取的水印信息修复被篡改图像。实验结果表明,该算法对删除、替换、篡改等破坏图像内容的恶意操作有精确的检测和定位,以及自修复能力。     

A Block-Level Image Tamper Detection Scheme Using Modulus Function Based Fragile Watermarking

Intentional illegitimate modification in any digital image data is one of the general malversations in the existing digital domain. Therefore in this work, the authors have devised a fragile watermarking technique for the localization of illegitimate modifications in the digital image content effectually. The proposed technique detects forged digital image content strongly in the block-level of two successive pixels. This scheme is performed at the block level, where the actual image is partitioned into non-overlapping blocks of size (1?×?2) pixels. Afterward, the block-level authentication code is generated from the MSB of two successive pixels of each block using averaging and modulus operations. The generated authentication code/watermark is encrypted using a logistic-map-based chaotic key series. The encrypted authentication code is embedded into two successive pixels of the corresponding block. Further, any form of forgery in the watermarked image can be detected by comparing its extracted authentication code and regenerated authentication code. The proposed procedure is successfully experienced on a variety of grayscale images, and the experimental results exhibit that watermarked images generated by this scheme are of considerably high quality in terms of PSNR, IF, and SSIM. The proposed method is capable of efficient forgery detection by achieving very high accuracy, NC, and true positive rate while maintaining considerably low false-positive and false-negative rates.

     

Improved image tamper localisation using chaotic maps and self-recovery

In this paper an image tamper localisation scheme is proposed in which authentication bits of a 2 × 2 image block are generated using the chaotic maps. Further the scheme is improved by including a self-recovery method to recover the tampered regions. To improve the quality of the recovered image, two different sets of restoration bits of a block are generated and each one is embedded into randomly selected distinct blocks. The proposed tamper detection scheme performs better than some of the recent schemes proposed by the researchers. The experimental results demonstrate the accuracy and fragility of the tamper detection scheme, and the efficacy of the recovery method.