图像半色调化算法研究综述

半色调化算法是图像打印输出的关键技术之一。介绍了简单阈值比较算法、使用随机数的半色调化算法、误差扩散算法、点扩散算法、按序抖动算法和抖动算法等一系列半色调化算法,并揭示了这些算法之间的联系。为了高效率地对图像做半色调化操作,商用光栅图像处理器一般使用抖动算法。抖动算法生成的半色调化图像的质量取决于所采用的抖动矩阵。基于几何分割设计半色调化抖动矩阵的方法可以在满足堆栈限制的前提下优化半色调化图像的质量。使用随机数的半色调化算法可以消除图像半色调化中产生的莫尔纹。随机半色调化算法的基础是将一定数量的随机点均匀地分布到一个正方形区域中。Asano提出了随机点均匀分布问题等价于圆形装填问题的命题,本文对该命题给出了初步的证明。最后,给出了一些有待进一步研究的图像半色调化课题。     

基于图像极小相似度的填充曲线半色调方法

扫描路径是数字半色调技术的关键环节。针对行扫描误差扩散方法、Hilbert—Peano曲线半色调方法的不足，提出了基于图像极小相似度的填充曲线半色调方法。该方法首先定义了一个与待处理图像像素个数相等的非连通带权图及其相关的一个连通带权图；其次求出后者的最小生成树；再次根据最小生成树将非连通的原图连接成连通图，该连通图即为图像的极小相似度曲线；最后从该曲线的任意一点出发，沿此曲线深度优先处理图像的每一个像素。实验表明，用新的扫描路径处理后得到的半色调图像的整体效果较好；图像不存在与扫描路径相关的规律性纹理；图像边缘更加平滑，其边缘对比度指标比现有方法优一个数量级；图像的非边缘区域误差最小。     

基于非理想打印机模型的半色调化图像质量评价方法研究

胶印工艺中印刷的内容需要半色调化成二值图像。为了评价半色调化算法和图像的质量,就要对输出图像的设备建模。现有的建模方法都基于理想打印机,假定输出图像的像素和输出设备的一个矩形区域的状态对应。然而理想打印机反映不了实际胶印工艺中的像素点重叠、极小网点丢失、网点扩大等基本现象。本研究的目标是建立一个面向胶印工艺的打印机模型,用于半色调化图像质量评价算法的研究。     

基于改进协方差矩阵的半色调图像分类研究

针对半色调图像分类中只存在0和1的特点,提出了一种基于改进的协方差矩阵在半色调图像中的分类方法。根据协方差矩阵在实现半色调图像分类中个数少且并未体现其局部和全局信息的特性,对协方差矩阵的底层特征进行改进。利用样本的局部特性和核密度估计方法,实现黎曼流形上的贝叶斯分类策略。实验中研究协方差矩阵的底层特征与传统协方差矩阵的特征提取方法并对其进行分类性能比较。实验结果表明,在半色调图像分类中,与传统的协方差矩阵相比较,改进的协方差矩阵提取出的特征在分类中平均错误分类率更低。     

数字半色调技术中的误差扩散算法的研究

误差扩散是一种非常优秀的调频半色调技术,但这种方法在图像高光和暗调以及阶调平滑区域会产生“蠕虫”,同时噪声较多,导致半色调图像的边缘不清晰。在Floyd和Steinberg的误差扩散算法的基础上,设计一种新的基于平均阈值和改变扫描路径的误差扩散算法——阈值采用平均值法,通过优化平均阈值方法中的γ值得到最优的半色调图像,同时扫描路径采用“蛇型”路径。实验结果表明该算法可以减少“蠕虫”,增强图像的边缘,提高半色调图像的主观视觉效果。     

一种大幅面二级设备输出多级半色调图像的方法

基于绿噪声技术，提出一种大幅面二级喷墨打印设备输出多级半色调图像的新方法，其中采用阈值调制技术设计了多级误差扩散方法较好地解决了伪轮廓问题。实验表明使用该方法大幅面二级喷墨打印设备输出多级半色调图像效果良好。     

图象硬拷贝的点密度方法——通过掩模矩阵构造不同灰度级的模矩阵

目前的图象硬拷贝设备主要是数字式的(如打印机、静电复印仪等),因此灰度图象的硬拷贝大多采用点密度方法。本文通过介绍掩模矩阵的生成算法和据其构造不同灰度级的模矩阵算法,给出一种可行的用于图象硬拷贝的点密度方法。     

低质量无约束人脸图像下的超分辨率摆正

针对人脸识别算法准确率受面部姿态、遮挡、图像分辨率等因素影响的问题,提出一种超分辨率摆正的方法,作用于低质量无约束输入图像上,生成高清晰度标准正面视图。主要通过估计输入图像与3D模型间的投影矩阵,产生标准正面视图,通过人脸对称性的特点,补全由于姿态、遮挡等原因所产生的面部缺失像素。在摆正过程中,为了提高图像分辨率以及避免面部像素信息丢失,引入一个16层的深度递归卷积神经网络进行超分辨率重构;并提出两个扩展：递归监督和跳跃链接,来降低网络训练难度以及缩小模型体量。在经过处理的LFW数据集上实验表明,该方法对人脸识别和性别检测算法的性能具有显著提升作用。     

基于混沌系统的对称图像加密方案

采用基于外部密钥的复合混沌系统对数字图像进行对称加密,由外部密钥产生混沌系统的初始值。复合混沌系统由2个Logistic系统构成,一个用来产生置换矩阵,对图像进行像素置换操作,另一个用来产生灰度扰乱序列。在对灰度扰乱过程中,使用基于外部密钥导出的子密钥对灰度扰乱序列进行采样。在置换过程中,通过加入置换矩阵信息,使位置置换和像素替代过程以简单有效的方式复合,提高系统的耦合性。     

基于谱聚类的多闭值图像分割方法

阈值法是图像分割的一种重要方法,在图像处理与目标识别中广为应用。因此,如何确定阈值是图像分割的关键。提出了一种新的图像阈值分割方法,即通过采用新的相似度函数的谱聚类算法(Dcut)确定图像阈值。采用基于灰度级的权值矩阵代替常用的基于图像像素级的权值矩阵描述图像像素的关系,因而算法需要的存储空间及实现的复杂性与其它基于图的图像分割方法相比大大减少。实验表明,该方法分割图像的时间少,且能够单阈值和多阈值分割图像,与现有的阈值分割方法相比,其具有更为优越的分割性能。     

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     

煤矿井下安全监控分站的设计及其仿真实现

为了设计一种具有低成本、低功耗、易操作、功能强且可靠性高的煤矿井下安全分站,针对煤矿安全生产实际,文章提出了采用MCS-51系列单片机为核心、具有CAN总线通信接口的煤矿井下安全监控分站的设计方案;首先给出煤矿井下安全监控分站的整体构架设计,然后着重阐述模拟量输入信号处理系统的设计过程,最后说明单片机最小系统及其键盘、显示、报警、通信等各个组成部分的设计;为验证设计方案的可行性与有效性,使用Proteus软件对设计内容进行仿真验证,设计的煤矿井下安全监控分站具有瓦斯、温度等模拟量参数超标报警功能和电机开停、风门开闭等开关量指示功能;仿真结果表明:设计的煤矿井下安全监控分站具有一定的实际应用价值.     

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。