基于EM算法的图像小波系数统计研究

基于小波分析的贝叶斯(Bayes)图像处理方法常常需要获得图像小波波系数的先验概率分布密度,该文提出,利用混合高斯模型对正交小波域中自然图像的父子小波系数的联合分布密度进行建模,运用非完备数据的极大似然估计算法——期望极大(EM)算法,对该模型的参数进行估计并且给出了联合分布密度函数的模型分量数与迭代次数的确定过程。最后,在后验均值(PM)方法下,把该联合分布密度模型运用于图像去噪研究;仿真结果表明该方法能够获得较好的效果。     

一种基于小波变换域的有意义图像盲水印算法

提出了一种基于小波变换域的有意义图像盲水印算法。算法中利用乘性隐藏方法在原始图像小波高频系数中嵌入一幅二值图像信息,通过拉普拉斯分布对原始图像小波变换域高频系数的统计分布特性进行建模,然后采用最大似然(ML)法推导得出了一个盲水印检测器,并且利用该检测器实现了一个有意义图像的盲水印算法。实验表明该算法具有较好的隐蔽性和鲁棒性。     

基于小波域隐马尔可夫树模型和SVR的定量隐写分析

本文结合小波域隐马尔可夫树模型(Hidden Markov Tree,HMT)和支持向量回归(Support Vector Regression,SVR)分析法提出了估计信息嵌入率的定量隐写分析。本文分别将垂直、水平和对角的小波系数建模为两状态的HMT模型,用EM算法(Estimation and Maximization Algorithm)对HMT模型进行训练得出包括状态初始概率、小波子带的转移概率和方差在内的模型参数,由这些参数构成图像的特征。然后结合SVR建立定量隐写分析器,并估计F5,outguess和MB三种隐写图的信息嵌入率。     

基于复小波噪声方差显著修正的SAR图像去噪

提出了一种基于复小波域统计建模与噪声方差估计显著性修正相结合的合成孔径雷达(Synthetic Aperture Radar,SAR)图像斑点噪声滤波方法。该方法首先通过对数变换将乘性噪声模型转化为加性噪声模型,然后对变换后的图像进行双树复小波变换(Dualtree Complex Wavelet Transform,DCWT),并对复数小波系数的统计分布进行建模。在此先验分布的基础上,通过运用贝叶斯估计方法从含噪系数中恢复原始系数,达到滤除噪声的目的。实验结果表明该方法在去除噪声的同时保留了图像的细节信息,取得了很好的降噪效果。     

基于MATLAB的图像小波子带广义高斯模型的研究

图像小波系数的统计分布具有非高斯特性,本文以采用广义高斯分布对图像子带小波系数进行建模为例,研究了广义高斯模型和模型参数的估计问题,介绍了利用MATLAB语言设计概率直方图以及求解模型参数超越方程的方法,最后对实验结果进行了讨论。     

小波与双边滤波的医学超声图像去噪

目的：医学超声图像中的斑点噪声降低了图像质量并且限制了超声图像自动化诊断技术的发展。针对斑点噪声问题,提出了一种新型的基于小波和双边滤波的去噪算法。方法：首先,根据医学超声图像在小波域内的统计特性,在通用小波阈值函数的基础之上,改进了小波阈值函数。其次,将无噪信号的小波系数和斑点噪声的小波系数分别建模为广义拉普拉斯分布模型和高斯分布模型,利用贝叶斯最大后验估计方法得到了新型的小波收缩算法,利用小波阈值法对小波域内的高频信号分量进行去噪。最后,对小波域内的低频信号分量进行双边滤波处理,然后利用小波逆变换便得到去噪后的图像。结果：在仿真实验中,通过与其它7种去噪算法作对比,观察峰值信噪比(PSNR)等图像质量评价指标,结果表明本文算法的去噪效果优于其他相关算法。临床超声图像的实验结果进一步验证了本文算法的去噪性能。结论：本文提出了一种新型的去噪算法,实验表明本文算法能够很好地抑制斑点噪声,并且能保留图像病灶边缘等细节。     

基于复数小波域广义高斯分布模型的纹理图像检索

由于在频域用能量参数来表示图像的特征矢量缺乏准确性,而且实数离散小波变换具有平移变化性和弱的方向选择性,为此针对以上问题提出了一种基于复数小波域广义高斯分布模型的纹理图像检索方法。该方法首先利用双树复数小波变换系数的统计特性来建立广义高斯分布的统计模型;然后基于该模型提取图像的特征矢量;最后利用Kullback-Leibler distance(KLD)测度算法进行纹理图像检索。对Brodatz图像库的仿真表明,新方法较双树复数小波算法的查准率提高6.96%,较基于Gabor纹理特征检索法的查准率提高了18.8%。同时复数小波系数统计模型具有旋转不变性。新方法对今后的纹理图像检索具有重要的理论与实际意义。     

基于复数小波域广义高斯分布模型的

由于在频域用能量参数来表示图像的特征矢量缺乏准确性,而且实数离散小波变换具有平移变化性和弱的方向选择性,为此针对以上问题提出了一种基于复数小波域广义高斯分布模型的纹理图像检索方法。该方法首先利用双树复数小波变换系数的统计特性来建立广义高斯分布的统计模型;然后基于该模型提取图像的特征矢量;最后利用KullbackLeibler distance(KLD)测度算法进行纹理图像检索。对Brodatz图像库的仿真表明,新方法较双树复数小波算法的查准率提高6.96%,较基于Gabor纹理特征检索法的查准率提高了18.8%。同时复数小波系数统计模型具有旋转不变性。新方法对今后的纹理图像检索具有重要的理论与实际意义。     

具有人类视觉特性的可见水印算法

论文提出一种基于小波变换的可见水印算法,该算法利用人类视觉模型的亮度CSF和纹理敏感特性,根据主图像和水印图像的局部和全局特征,建立确定水印嵌入的拉伸系数数学模型。首先描述了人类视觉及小波分解系数分析,给出了小波系数视觉重要性权重值。把原图像和水印图像小波系数频率子带分成不同的块,基于视觉掩模对子块进行分类。利用人眼的纹理敏感特性,进一步增强了嵌入水印的图像视觉质量。仿真实验表明该算法结果良好。     

复数小波域的高斯尺度混合模型图像降噪

由于复数小波变换具有近似平移不变性和良好的方向选择性,因此适用于图像去噪。为了取得更好的降噪效果,提出了一种基于复数小波的高斯尺度混合模型降噪算法。该算法首先对自然图像的复数小波系数建立统计模型,即将位于相邻位置和尺度的系数邻域建模为一个高斯尺度混合模型;然后用该模型对子带系数进行贝叶斯最小均方估计,以达到降低噪声的目的。由于这一模型很好地利用了复数小波系数幅值尺度间和尺度内的相关性,因此可以取得较好的降噪效果。实验结果表明,该算法无论从峰值信噪比还是从主观视觉上都优于一些传统的降噪算法。     

Only connect: teaching, technology and telesis

Abstract This paper describes an approach to the design of interactive multimedia materials being developed in a European Community project. The developmental process is seen as a dialogue between technologists and teachers. This dialogue is often problematic because of the differences in training, experience and culture between them. Conditions needed for fruitful dialogue are described and the generic model for learning design used in the project is explained.     

European Community policy and the market

Abstract This paper starts with some reflections on the policy considerations and priorities which are shaping European Commission (EC) research programmes. Then it attempts to position the current projects which seek to capitalise on information and communications technologies for learning in relation to these priorities and the apparent realities of the marketplace. It concludes that while there are grounds to be optimistic about the contribution EC programmes can make to the efficiency and standard of education and training, they are still too technology driven.     

一种自适应子融合集成多分类器方法

融合集成方法已经广泛应用在模式识别领域,然而一些基分类器实时性能稳定性较差,导致多分类器融合性能差,针对上述问题本文提出了一种新的基于多分类器的子融合集成分类器系统。该方法考虑在度量层融合层次之上通过对各类基多分类器进行动态选择,票数最多的类别作为融合系统中对特征向量识别的类别,构成一种新的自适应子融合集成分类器方法。实验表明,该方法比传统的分类器以及分类融合方法识别准确率明显更高,具有更好的鲁棒性。     

Avoiding semantic and temporal gaps in developing software intensive systems

Development of software intensive systems (systems) in practice involves a series of self-contained phases for the lifecycle of a system. Semantic and temporal gaps, which occur among phases and among developer disciplines within and across phases, hinder the ongoing development of a system because of the interdependencies among phases and among disciplines. Such gaps are magnified among systems that are developed at different times by different development teams, which may limit reuse of artifacts of systems development and interoperability among the systems. This article discusses such gaps and a systems development process for avoiding them.     

Designing economic np control charts: A programmed simulation approach

This paper presents control charts models and the necessary simulation software for the location of economic values of the control parameters. The simulation program is written in FORTRAN, requires only 10K of main storage, and can run on most mini and micro computers. Two models are presented - one describes the process when it is operating at full capacity and the other when the process is operating under capacity. The models allow the product quality to deteriorate to a further level before an existing out-of-control state is detected, and they can also be used in situations where no prior knowledge exists of the out-of-control causes and the resulting proportion defectives.     

The development of robot art

Going through a few examples of robot artists who are recognized worldwide, we try to analyze the deepest meaning of what is called “robot art” and the related art field definition. We also try to highlight its well-marked borders, such as kinetic sculptures, kinetic art, cyber art, and cyberpunk. A brief excursion into the importance of the context, the message, and its semiotics is also provided, case by case, together with a few hints on the history of this discipline in the light of an artistic perspective. Therefore, the aim of this article is to try to summarize the main characteristics that might classify robot art as a unique and innovative discipline, and to track down some of the principles by which a robotic artifact can or cannot be considered an art piece in terms of social, cultural, and strictly artistic interest. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Explanation and prediction: an architecture for default and abductive reasoning

Although there are many arguments that logic is an appropriate tool for artificial intelligence, there has been a perceived problem with the monotonicity of classical logic. This paper elaborates on the idea that reasoning should be viewed as theory formation where logic tells us the consequences of our assumptions. The two activities of predicting what is expected to be true and explaining observations are considered in a simple theory formation framework. Properties of each activity are discussed, along with a number of proposals as to what should be predicted or accepted as reasonable explanations. An architecture is proposed to combine explanation and prediction into one coherent framework. Algorithms used to implement the system as well as examples from a running implementation are given.     

Three Process Perspectives: Organizations, Teams, and People

This paper provides the author's personal views and perspectives on software process improvement. Starting with his first work on technology assessment in IBM over 20 years ago, Watts Humphrey describes the process improvement work he has been directly involved in. This includes the development of the early process assessment methods, the original design of the CMM, and the introduction of the Personal Software Process (PSP)^SM and Team Software Process (TSP){^SM}. In addition to describing the original motivation for this work, the author also reviews many of the problems he and his associates encountered and why they solved them the way they did. He also comments on the outstanding issues and likely directions for future work. Finally, this work has built on the experiences and contributions of many people. Mr. Humphrey only describes work that he was personally involved in and he names many of the key contributors. However, so many people have been involved in this work that a full list of the important participants would be impractical.     

How do children do mathematics with LOGO?

Abstract  This paper considers some results of a study designed to investigate the kinds of mathematical activity undertaken by children (aged between 8 and 11) as they learned to program in LOGO. A model of learning modes is proposed, which attempts to describe the ways in which children used and acquired understanding of the programming/mathematical concepts involved. The remainder of the paper is concerned with discussing the validity and limitations of the model, and its implications for further research and curriculum development.