中值滤波与各向异性扩散相结合的医学图像滤波方法

医学图像的滤波处理,须保留具有重要诊断意义的边缘细节信息。针对Perona-Malik(PM)各向异性扩散模型遇到强噪声则失效和扩散门限参数K依靠经验选取的不足,提出了一种改进的各向异性扩散算法。将PM算法与中值滤波结合,用经过中值滤波平滑后的梯度模代替原始图像的梯度模,以控制扩散的过程。应用自适应扩散门限(当前邻域内梯度的绝对偏差中值(MAD))和迭代终止准则,提高算法鲁棒性和效率。实验分别对超声心动图、CT图像和Lena图像进行去噪处理,用峰值信噪比(PSNR)和边缘保持能力EPI作为评价标准。实验结果表明,改进算法优于PM算法和Catte-PM方法,在提高信噪比的同时保留了图像的细节信息,可以更好地满足医学图像的使用要求。     

中值滤波与各向异性扩散相结合的医学图像滤波方法

医学图像的滤波处理,须保留具有重要诊断意义的边缘细节信息。针对Perona-Malik(PM)各向异性扩散模型遇到强噪声则失效和扩散门限参数K依靠经验选取的不足,提出了一种改进的各向异性扩散算法。将PM算法与中值滤波结合,用经过中值滤波平滑后的梯度模代替原始图像的梯度模,以控制扩散的过程。应用自适应扩散门限(当前邻域内梯度的绝对偏差中值(MAD))和迭代终止准则,提高算法鲁棒性和效率。实验分别对超声心动图、CT图像和Lena图像进行去噪处理,用峰值信噪比(PSNR)和边缘保持能力EPI作为评价标准。实验结果表明,改进算法优于PM算法和Catte-PM方法,在提高信噪比的同时保留了图像的细节信息,可以更好地满足医学图像的使用要求。     

基于异性扩散-中值滤波的超声医学图像去噪方法

针对超声图像存在一种特殊的斑点噪声,使图像边界与细节变得模糊而严重影响图像质量的问题,提出了一种新的去除医学图像斑点噪声的方法,它利用中值滤波和各向异性扩散相结合,不仅可以有效地去除噪声而且很好地保持了边缘、局部细节信息.此外,该方法在扩散过程中,梯度阈值选取的不同对图像结果影响很小,这极大地提高了该算法的健壮性.实验中,通过和各向异性扩散、中值滤波等方法的比较,表明该方法具有良好的去噪效果.     

改进的各向异性扩散图像去噪算法

图像去噪是图像处理中的重要环节,经典的图像去噪算法,如中值滤波、高斯滤波和加权平均滤波等,去噪效果都不是很理想。传统方法在去除噪声的同时,会使图像的边缘也变得模糊。偏微分方程(PDE)是近年比较流行的图像处理方法,它具有各向异性的特点,在去除噪声的同时,能很好地保持图像的边缘。基于现有算法,提出了一种改进的去噪算法。将传统P-M算子中的固定边缘阈值改为随梯度模变化的自适应阈值,并结合图像结构张量构造一个扩散函数。在图像平坦区,改进的P-M模型具有各向同性的特点,有利于平滑噪声;而在图像边缘处,该模型只沿切线方向扩散,有利于保护图像细节。试验表明,改进的P-M模型能很好地改善图像去噪效果,同时也能很好地保持图像的边缘。     

一种改进的自适应中值滤波算法

针对未知脉冲噪声强度的退化图像的去噪,提出了一种新的自适应中值滤波算法,该算法主要基于以下两点：（1）根据模糊数学里的模糊度理论及随机脉冲噪声本身的去噪特点,提出了模糊指标的概念,并通过反向二阶拟合来获得噪声的强度信息;（2）引入了反映图像边缘信息的Prewitt梯度算子,并通过实验来得到合适的梯度阚值,以更好地保持图像的边缘等细节信息.通过将该算法与传统的中值滤波、基于排序阈值的开关中值滤波以及Sorin Zoican提出的改进的中值滤波进行的对比实验表明,该算法对噪声的强度有很好的估计,不仅提高了噪声去除的自适应性,尤其对含噪声多的图像的处理效果更为理想.     

改进的各向异性复扩散模型的医学图像去噪方法

对医学图像进行有效的去噪并保持边缘信息,有利于图像的后续处理.本文分析P-M模型和Gilboa的复扩散模型以及它们的不足,提出一种改进的各向异性复扩散模型.该方法先用中值滤波对图像进行预处理,去除梯度值大的噪声点,然后用图像的虚部求扩散系数,以此引导扩散模型中的边缘检测函数,再进行八邻域像素的扩散过程.实验表明,该方法能达到较理想的去噪和保持边缘的效果,而且减少了迭代次数,缩短了计算时间.     

一种基于边缘检测的改进的中值滤波去噪方法

中值滤波是一种去除椒盐噪声的有效算法,在现实生活中应用相当广泛。传统的中值滤波在去噪的同时很容易丢失图像的边缘信息。本文提出一种基于边缘检测的改进的中值滤波去噪算法。它先将含噪图像的边缘信息检测出来,然后将边缘信息保存下来,再对原含噪图像用中值滤波进行图像去噪,然后对于保存下来的边缘信息用小模板进行去噪,再用该小模板去噪后的边缘信息区替换中值滤波后的边缘信息。最后通过实验验证,此去噪算法可以在去噪的同时更好地保护图像的边缘信息。     

基于边缘扩散的医学图像非线性去噪算法*

在对医学图像去噪的同时保留边缘信息,对于后期的诊断具有重要的意义。分析了ＰＭ和Ｃａｔｔｅ算法 以及它们的不足,提出了一种基于边缘扩散的非线性去噪方法,通过边缘检测把图像分为边缘和非边缘两部分, 非边缘区域通过各向同性算法去噪;边缘区域通过各向异性算法去噪,改进扩散形式,只沿边缘方向扩散去噪。 实验表明方法非常有效,带噪声的医学图像经过改进后的算法去噪处理,图像质量得到明显的改善。     

基于局部方差改进的超声图像各向异性扩散去噪算法

针对各向异性扩散算法不能有效区分强噪声和弱边缘的缺点,提出了一种基于图像局部统计特征改进的算法。该算法在对图像进行各向异性扩散去噪的过程中,使用梯度阈值找到图像中灰度变化较大的点,再通过计算局部方差和局部去心方差的差值判断该点是否为噪声点,若是噪声点则使用均值滤波处理。对仿真图像和临床超声图像的实验结果表明:与传统的各向异性扩散算法相比,改进的算法在图像去噪和特征保留的能力上得到了良好的提升。     

基于解剖非局部先验的模糊扩散PET重建算法

针对传统最大后验(MAP)算法出现阶梯伪影以及不能有效保持重建图像低梯度值处细节信息的问题,提出了一种基于解剖非局部先验的模糊扩散正电子发射计算机断层扫描(PET)重建算法。首先,对中值先验分布的MAP重建进行改进,在每次中值滤波前引入结合模糊函数的各向异性扩散滤波器;然后,采用模糊隶属度函数作为各向异性扩散过程的扩散系数,并结合解剖非局部先验来考虑图像的细节信息。仿真结果表明,与传统算法相比,该算法提高了信噪比(SNR),具有良好的抗噪性;同时视觉效果较好,图像边缘清晰,在抑制噪声和边缘保持方面取得了良好的折中。     

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.     

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。     

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.