曲线演化的图像分割算法改进研究

研究提高曲线演化的图像自动检测效果问题.由于图像识别度低、准确度低,传统 Chan-vese 活动轮廓模型(C-V 模型)不能检测到远离活动轮廓线且与平均灰度值相差大的边缘.图像分割算法采用水平集演化曲线外图像的目标和背景的灰度加权平均值,通过调节权重值,使演化曲线能准确快速收敛于远离平均灰度强度的图像边缘上.该算法具备拓扑变化能力,分割速度快,能克服原 C-V 模型不能检测到边缘缺陷,加速图像分割的收敛速度,提高分割效果.     

结合分水岭算法的水平集医学图像分割方法

由于医学图像中的复杂目标通常难以被完全分割,提出标记分水岭与改进型Li模型的组合图像分割算法。改进型Li模型构造了符号压力函数来取代传统的停止函数,解决了曲线单向演化的问题。标记分水岭具有较强的抑制噪声的能力,对医学图像的弱边缘具有较强的捕获能力。所以首先运用标记分水岭算法对图像进行预分割,快速准确定位目标区域边缘信息。再引入改进型Li模型算法,通过符号压力函数来指引曲线演化方向,控制演化速度大小,实现对复杂目标的完全分割。实验结果表明:全局信息和边缘信息都能被获得,该组合算法对医学图像中的复杂目标的分割效果较满意。     

基于区域划分的曲线演化多目标分割

该文在小波变换的多分辨率框架下建立了一种基于曲线演化的多目标分割算法，并且目标分割由两步实现：(1)区域划分，将图像域分为多个子区域；(2)在各子区域中，采用基于简化的Mumford-Shah模型的曲线演化方法进行分割，从而实现了多个(不局限于一个)不同平均灰度目标的分割．由于算法建立在区域划分和CV方法的基础上，因而对受噪声影响大、边缘模糊的多个不同质区域仍能得到正确的分割．同时算法从多方面提高了曲线演化速度．     

基于方向Snake模型的心脏磁共振图像左心室内外膜分割

针对心脏磁共振图像(MRI)左心室内膜与外膜边缘方向不同的特点,提出一种基于曲线演化框架的方向主动轮廓模型进行左心室内外膜分割。曲线演化方程中包含基于图像边缘与区域灰度特征的混合几何流。几何流中的边缘信息项由经Fast Marching方法扩展后的动态方向梯度矢量流场（DDGVF）构成,用以引导曲线向具有不同方向的目标边缘运动,而区域灰度信息项则由Chan-Vese (CV)模型构成,用以防止曲线在演化过程中受其他边缘成分的影响而发生泄漏。最终的曲线演化方程采用水平集方法求解。实验结果表明,所提方法能够较为准确地分割出心脏MRI图像中的左心室内外膜并具有较好的鲁棒性,对于实现基于心脏MRI图像的左心室心肌区域自动快速分割和心脏功能分析与评价具有一定的应用价值。     

修正局部极小值的局部灰度差异分割模型

针对现有局部模型在分割灰度不均匀图像时容易陷入局部极小值,导致演化曲线停留在背景处或目标内部无法继续演化从而造成分割失败的现象,提出本模型。该模型在能量泛函中增加局部灰度差异项,通过最大化演化曲线上所有点的邻域内目标和背景的差异来驱动演化曲线越过图像背景处或目标内部,直到准确地停留在目标边缘。实验结果表明提出的模型可以有效地解决局部模型因陷入局部极小值而导致的误分割问题,同时提高对分割灰度不均匀等复杂图像的准确性,并减小对初始轮廓的敏感性。     

灰度差能量函数引导的图像分割自适应C-V模型

作为几何活动轮廓模型(GACM)的一个标志性模型,C-V模型在图像分割应用中因具有对目标遮挡和边缘噪声的鲁棒性而受到关注.然而该模型通常不能较好地处理复杂的异质图像,并且有对演化曲线的初始位置较为敏感和计算复杂度高等弱点.依据演化曲线内、外区域平均灰度值差的绝对值越大,演化曲线越靠近准确目标边缘的特性,提出一种基于灰度差能量函数引导的图像分割自适应C-V模型.该模型通过构造基于轮廓曲线内、外区域平均灰度差引导函数自适应地调整演化曲线的运动趋势,使得曲线演化可在一个有效的"窄带"范围内进行,保证轮廓曲线内、外部区域灰度计算的局部均一性,增强对目标细节信息的捕捉能力,同时也在一定程度上提高模型的计算速度和对轮廓曲线初始位置的适应性.大量的仿真实验验证该模型的有效性.     

基于ROI提取的多目标图像水平集分割

针对包含多个目标或目标灰度与背景灰度接近的图像分割问题,借鉴人类视觉系统的关注机制和多分辨性,提出一种多尺度框架下基于感兴趣区域提取的图像水平集分割方法。对原图像小波变换的低频分量图应用显著性特征提取出感兴趣区域,将图像域分成多个感兴趣子区域和一个背景子区域,在各目标子区域中,采用C-V模型方法进行曲线演化,并对各子区域分割结果进行合成。仿真结果标明,该算法能有效分割多目标图像。     

一种类圆形图像目标分割方法的研究

研究工业视觉识别系统与图像处理有密切关系.针对类圆形图像背景和目标在色彩和灰度上相近难以准确分割的问题,为了提供精确图像目标,提出了一种新型的类圆形目标分割方法.采用带方向的序贯滤波和方向边缘检测,有效去除背景干扰信息;边缘检测的结果填充后进行图像投影,据此得到待分割目标的大致区域,再次滤波得到较佳的预分割结果;采用中心扫描算法,接合投影曲线完成粗分割,得到边缘曲线;最后根据边缘曲率对边缘线进行矫正,实现了类圆形目标的完整提取.通过实验表明,对灰度相近的图像能进行有效提取,避免了阈值法的局限性,提高了类圆形目标分割的完整性和精确度.     

基于水平集的医学图像分割改进算法

医学影像分割是图像分割中的难点,具有重要的应用价值。针对医学影像的特点和图像分割算法的性能差异,提出了一种水平集医学图像分割改进算法。首先通过曲线演化仿真,得出水平集算法核心-速度函数;其次选定速度函数实现对图像的粗略分割,将灰度值较大的区域设置成灰度值较小的值,通过仿真演化准确找到图像中目标区域;最后利用选定的速度函数通过初始算法,经过一定次数的迭代操作后实现了医学影像的准确分割。实验结果表明:该算法可以精确地找到肿瘤所在区域,具有较好的分割性能和一定的鲁棒性。
     

一种基于主动轮廓模型的医学图像序列分割算法

介绍了一种结合live wire算法和活动轮廓模型的医学图像序列的分割方法.通过把live wire算法和图像分割中一般的区域增长方法结合,对传统live wire算法进行了改进,并用改进后的算法对医学图像序列中的单张或多张切片进行交互式地准确分割.然后计算机利用活动轮廓模型自动分割相邻的未分割切片.还通过在活动轮廓模型的边缘点中引入记录已分割物体边缘附近局部区域特征的灰度模型,把已分割切片中的物体与背景的局部区域特征带入相邻的未分割切片中,并用由灰度模型定义的区域相似性代替活动轮廓模型中的外能来引导边缘轮廓收敛到物体的实际边缘.最后介绍了一种基于live wire算法思想的简单的分割结果交互式修复方法.实验结果表明该算法仅需少量用户交互就能快速准确地从医学图像序列中分割出感兴趣的物体,在医学图像分析中具有实用价值.     

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.