Performance optimization for multicast packet authentication

1 Introduction a Many secure multicast systems, such as stock quotes, video conferencing, should provide mechanisms for recipients to authenticate messages they received. Packet authentication in multicast environments is a challenge for two reasons. First, the standard Message Authentication Code (MAC) technique is no longer available because of the fact that all members in a multicast group share the same session key. Another obvious way is to sign each packet using the sender’s private …     

彩色人脸图像鉴别特征抽取综述

近年来,人脸识别技术得到了迅猛发展,而基于彩色图像人脸识别的研究尚处于初级阶段.本文在对所有彩色人脸图像表示法和鉴别特征抽取方法分析比较的基础上,综述了彩色人脸鉴别特征抽取的研究现状.     

颜色和形状图像检索在邢台市智能交通的应用

给出颜色空间模型,阐述颜色特征的检索方法,并对直方图相交方法和其他方法的利弊进行了对比分析;在基于颜色特征的检索基础上,针对图像检索的另一个重要特征形状,提出了对轮廓特征的索引和对区域特征的索引;基于颜色特征和形状特征为邢台市智能交通系统设计了一个图像检索系统。     

A new semi-fragile watermarking algorithm for image authentication

1 Introduction1 With the rapid development of Internet, digital multimedia can be easily shared via computer networks and conveniently processed for queries in databases. At the same time, the powerful multimedia manipulation software has made it possible to edit and alter the media’s content seamlessly, which breeds the demand of a secure authentication system to verify authentication. Digital watermarking has been proposed as a possible solution for data and tamper detection. An authentica…     

基于奇异值测度和颜色纹理的图像块特征向量

In this work, image feature vectors are formed for blocks containing sufficient information, which are selected using a singular-value criterion. When the ratio between the first two SVs are below a given threshold, the block is considered informative. A total of 12 features including statistics of brightness, color components and texture measures are used to form intermediate vectors. Principal component analysis is then performed to reduce the dimension to 6 to give the final feature vectors. Relevance of the constructed feature vectors is demonstrated by experiments in which k-means clustering is used to group the vectors hence the blocks. Blocks falling into the same group show similar visual appearances.     

航摄影像特征点提取算法研究

随着无人机在测绘领域的广泛应用,航摄影像处理已成为国内外关注的热点。为寻求更适合航摄影像特征点提取的算法,对目前国内外几种常用特征点提取算法进行对比分析,结果表明,Moravec算子相较于其它算子,原理最为简单,但图像处理效果不佳。为此,利用C#工具实现Moravec算子,并通过图像处理实验,从计算速度、提取质量、定位精度、抗噪能力等方面对其进行全面分析,得出该算子在提取质量、定位精度与抗噪能力等方面均性能较差,该结论为今后对其优化改进提供了明确的研究方向。     

机器人焊缝图像特征提取技术研究

机器人焊接因受到加工精度、组装精度以及环境等因素的影响,焊枪在运行时不可避免地会偏离焊缝位置,从而影响焊接品质。因此对焊缝图像进行特征提取,实现机器人焊接自动跟踪,即通过将焊缝与背景进行有效区分,提取出焊缝图像的中心线,为自动跟踪系统提供可靠信息,帮助机器人焊枪纠偏,提高焊接精度,实现焊接过程的自动化、柔性化、信息化、智能化。     

基于C#的图像颜色特征值的提取与匹配

数字图像数据特征值的提取和匹配,是基于内容的图像检索的基础,本文利用C#语言实现了一种图像颜色特征值的提取和匹配算法。     

稳健图像Hash研究进展

The easy generation, storage, transmission and reproduction of digital images have caused serious abuse and security problems. Assurance of the rightful ownership, integrity, and authenticity is a major concern to the academia as well as the industry. On the other hand, efficient search of the huge amount of images has become a great challenge. Image hashing is a technique suitable for use in image authentication and content based image retrieval （CBIR）. In this article, we review some representative image hashing techniques proposed in the recent years, with emphases on how to meet the conflicting requirements of perceptual robustness and security. Following a brief introduction to some earlier methods, we focus on a typical two-stage structure and some geometric-distortion resilient techniques. We then introduce two image hashing approaches developed in our own research, and reveal security problems in some existing methods due to the absence of secret keys in certain stage of the image feature extraction, or availability of a large quantity of images, keys, or the hash function to the adversary. More research efforts are needed in developing truly robust and secure image hashing techniques.     

维吾尔语拟声词形象色彩探究

维吾尔语是维吾尔族文化和风俗习惯的综合反映,维吾尔语拟声词的形象色彩能使语言描述更加生动形象。本文主要根据维吾尔语的语言特点,分析维吾尔语拟声词的形象色彩及其分类、修辞作用、特点和修饰形象色彩丢失的原因,以提高维吾尔语语言教学。     

高分辨率天文图像分块并行特征提取方法研究

图像并行处理研究较多,但鲜有分块文献以及图像分块机制研究。针对高分辨率天文图像数据量大、特征提取速度缓慢的问题,研究了图像分块并行处理策略。通过对高分辨天文图像在不同分块分辨率下的特征提取时间进行对比分析,找到特征提取速度最快的分块分辨率。通过实验对比和分析得到分块策略,通过实验验证了方法的有效性。     

一种改进的彩色人脸鉴别特征抽取方法及自动识别

针对传统的线性分析方法中都需要的平均样本的共性,提出了基于中间样本的人脸识别．这种方法有效去除了干扰样本对平均样本的影响,并结合彩色人脸识别,提出了基于中间样本的彩色人脸鉴别特征抽取及自动识别方法．最后,在国际通用的AR标准彩色人脸库中进行了大量实验,验证了算法的有效性．     

基于认证测试的鲁棒电子邮件协议形式化分析(英文)

基于认证测试方法及strand space模型,形式化分析了具有完美前向机密性的鲁棒电子邮件协议,指出该协议存在安全缺陷.同时给出了针对该协议的中间人攻击方法,即攻击者在协议的接收阶段通过伪造消息即可欺骗通信双方,使通信双方与其共享错误的会话密钥,由此使得协议的完美前向机密性得不到保证,针对协议的上述缺陷,提出一种改进方案,即通过在协议的接收阶段加入相应的签名信息,以保证改进协议能够克服中间人攻击并且提供完美前向机密性.最后,基于认证测试方法及strand space模型,形式化证明了改进协议在发起者、接收者及服务器之间的安全认证,确保了改进协议具备真正的完美前向机密性.     

Web文本挖掘中的特征表示与特征提取技术

Web文本挖掘是人工智能一个崭新的研究领域。分词、特征表示和特征子集提取技术是文本挖掘过程中前期的基础性工作。介绍了文本挖掘中分词、特征表示及特征子集提取的常用技术及发展趋势。     

基于分形的快速最大熵红外图像特征检测

文章针对红外图像目标检测问题,提出一种基于分形的快速最大熵的红外图像特征检测算法.该算法利用DBC方法计算分维数,根据人造物和自然背景分形维差异,确定目标区域;最后,通过二维最大熵原则确定最佳阈值,实现对单目标或者多目标图像分割.该算法能够较好实现红外图像特征检测,有效抑制背景和噪声.     

不同图像之间拼接篡改的数字图像检测研究

对基于CFA（颜色滤波阵列）模型的篡改检测算法进行了改进。其检测过程为：首先,利用插值算法得到像素位置的预测误差,根据预测误差计算出CFA单元特征;然后,利用EM（期望最大化）算法估计特征模型的参数,算法对篡改位置的均值不做事先确定（从实验来看这种改进具有较好的效果）;最后,利用贝叶斯理论计算出每个像素点的似然率,根据似然率的不同来定位篡改区域。在进行单CFA阵列模式检测的情况下,对多种CFA阵列模式的图像也进行了检测分析,实验结果显示,该算法能够对多种CFA阵列模式的图像准确定位篡改区域。     

复杂背景图像文本信息提取技术研究

许多图像中包含的文本信息对于图像高层语义内容的自动理解、图像索引和检索非常有用。复杂背景图像中文本信息的提取一般包括文字的自动检测、定位、提取、分割和识别,由于图像中文本的大小、字体、字形、位置、排列和图像的清晰度、对比度等不定,使文本自动提取非常困难。文章对目前国内外图像中文本提取主要技术和发展方向进行了综述,便于该领域的研究人员了解和借鉴,同时指出了今后研究方向的热点。     

Multi-core based parallel computing technique for content-based image retrieval

In this paper, we propose a parallel computing technique for content-based image retrieval （CBIR） system. This technique is mainly used for single node with multi-core processor, which is different from those based on cluster or network computing architecture. Due to its specific applications （such as medical image processing） and the harsh terms of hardware resource requirement, the CBIR system has been prevented from being widely used. With the increasing volume of the image database, the widespread use of multi-core processors, and the requirement of the retrieval accuracy and speed, we need to achieve a retrieval strategy which is based on multi-core processor to make the retrieval faster and more convenient than before. Experimental results demonstrate that this parallel architecture can significantly improve the performance of retrieval system. In addition, we also propose an efficient parallel technique with the combinations of the cluster and the multi-core techniques, which is supposed to gear to the new trend of the cloud computing.     

特定人孤立词语音识别系统的特征提取方法研究

随着语音识别技术的不断发展,特定人孤立词语音识别技术己基本成熟并逐渐开始应用于社会众多领域。而系统所追求的成本低、速度快和识别率高等目标,使主因素特征参数的选取成为其重点和难点。在实验的基础上对特征提取方法进行了深入的研究,提出了对传统Mel倒谱参数的改进方法,有效提高了系统的识别性能。     

基于投影和纹理信息融合的医学图像检索

为克服基于单一特征进行医学图像检索存在的局限性,文章提出了一种新的基于投影和纹理信息融合的检索算法,分析医学图像的特点,引入颜色投影并选择综合性能较高的特征进行融合,调整各特征的权重,最后运用加权欧氏距离进行相似性度量．实验结果表明,该算法检索速度快,具有较高的查准率．