修正大气耗散函数的单幅图像去雾

目的 针对暗原色先验原理对雾霾图像中天空或白色物体等明亮区域透射率估计不足,导致该区域去雾后彩色失真的问题,提出一种基于暗原色先验和引导滤波修正大气耗散函数的单幅图像去雾算法。方法 首先,基于暗原色先验模型得到大气耗散函数的粗估计值;其次,构造一个修正函数,纠正暗先验失效的明亮区域的大气耗散函数;然后,对修正后的大气耗散函数和求得的初始传输图分别利用引导滤波进行优化,平滑图像边缘的同时保持图像细节信息;最后,由优化后的传输图和估计的大气光值得到复原图像。结果 选取多幅经典图像进行对比实验,并利用峰值信噪比和均方误差衡量去雾结果的失真程度。实验结果表明,本文算法不但在非明亮区域可以得到较好的去雾效果,而且也能使图像中的明亮区域保持原有色彩,相比而言本文算法得到的复原图像整体失真较少;对于大小为460×300像素的图像,本文算法与He方法相比,得到的复原图像峰值信噪比提高了0.6005 dB,均方误差降低了0.0026,耗时缩短了29.6220 s。结论 对于雾天包含明亮区域的降质图像,提出了一种修正大气耗散函数的单幅图像去雾算法。实验结果的主观和客观评价表明本文算法对天空或白色物体等明亮区域能得到较好的去雾效果,有效改善了暗原色先验原理对图像中明亮区域造成的彩色失真问题。     

含有大片天空区域图像的去雾算法

为提高包含天空区域图像的去雾效果,解决暗原色先验原理去雾容易导致天空区域色彩失真以及图像整体亮度较暗的问题,针对含有大片天空的图像,提出一种基于天空分割和色调映射的图像去雾算法.在HSI颜色空间中利用图像众数和图像连通区域提出天空识别算法,分割出天空与非天空区域;然后根据暗原色先验原理分别求取二者透射率,并在天空区域完成大气光值的估计;最后在RGB空间中利用大气散射模型复原图像,并经过改进的自适应色调映射得到最终的去雾图像.采用合成雾图、实景雾图和网络收集雾图进行实验的结果表明,该算法在主观视觉和客观指标方面均能得到质量更好的去雾图像.     

结合天空检测与纹理平滑的图像去雾

目的 针对已有图像去雾方法中存在的天空灰暗以及透射率分布与实际情况不一致导致的对比度增强不足等问题,以暗通道先验图像去雾方法为基础,提出结合天空检测与纹理滤波的图像去雾算法。方法 首先,设计了一个基于天空检测的大气光自适应估计策略,以天空区域亮度值较低的像素为依据估计大气光值,能够避免天空色彩失真,获得更明亮且干净的天空恢复结果;其次,对输入图像进行纹理平滑预处理以保持同一平面物体内的像素颜色一致性,并提出一个基于块偏移与导向滤波的透射率精确化计算策略,使透射率估值更符合深度信息的变化趋势,以提升无雾图像的对比度与色彩饱和度;最后,对复原结果进行联合双边滤波后处理,以降低噪声的影响。结果 本文算法得到的大气光估值更为合理,对于不符合暗通道先验的天空区域,能够取得更为自然的天空复原结果;本文算法得到的透射率的变化趋势与实际场景深度之间具有更高的一致性,对于符合暗通道先验的非天空区域,能够取得高对比度与高色彩饱和度的恢复结果。结论 本文算法在大气光与透射率的估值的准确性以及无雾图像的对比度与清晰度增强方面都得到了有效提升,具有较高的鲁棒性,适用于视频监控、交通监管和目标识别等户外获取图像的诸多应用领域。     

融合GF-MSRCR和暗通道先验的图像去雾

目的 针对雾天图像高亮和雾浓区域中容易出现场景透射率值求取不准确,导致复原后的图像细节丢失、出现光晕现象、对比度和色彩难以满足人眼的视觉特性等问题,提出了一种融合引导滤波优化的色彩恢复多尺度视网膜算法（GF-MSRCR）和暗通道先验的图像去雾算法。方法 首先利用加权四叉树方法从最小通道图中快速搜索全局大气光值,再从图像增强角度应用GF-MSRCR算法初步估计场景透射率值,依据暗通道先验原理对最小通道图进行二次估测,根据两次求取结果按一定比例进行像素级图像融合,得到场景透射率估计值;利用变差函数修正估计值,经中值滤波进一步优化得到场景透射率的精确值,最后通过大气散射模型恢复雾天图像,调整对比度和恢复颜色后,得到了轮廓完整且细节清晰的无雾图像。结果 理论分析和实验结果表明,经本文算法去雾处理后的图像信息熵、对比度、平均梯度、结构相似性分别平均提升了7.87%、21.95%、47.73%和15.58%,同时运行时间缩短了53.22%,对近景、含小部分天空区域、含大片天空区域和含白色物体场景的多种类型雾天图像显示出较好的复原效果。结论 融合GF-MSRCR和暗通道先验的图像去雾算法能快速有效保留图像的细节信息、消除光晕,满足了人眼的视觉特性,具有一定的实用性以及普适性。     

雾天交通场景中单幅图像去雾

目的 针对雾天交通场景中通常含有大片天空区域,传统去雾方法在复原这些图像时容易产生光晕、色彩失真等现象。提出一种基于天空区域分割和暗通道先验理论的图像去雾方法。方法 首先提出一种基于最大类间方差法（OTSU）的图像分割算法来自动分离天空区域,然后将天空区域的平均强度值作为大气光值,从而改进场景传输率的估计。结果 本文方法不仅有效地解决了图像去雾后出现光晕和色彩失真等问题,与He Kaiming以及Fattal的方法相比,本文方法去雾后的图像更加真实、自然、平滑。结论 实验结果表明,本文方法能够很好地完成对雾天交通图像的复原,可为道路交通监管提供一种有效的理论基础和技术支撑。     

基于改进暗通道和导向滤波的单幅图像去雾算法

针对单幅雾霾图像中包含的大面积天空或白色物体等区域暗通道先验失效和导向滤波去雾方法去雾不彻底的问题, 提出了一种基于改进暗通道和导向滤波的单幅图像去雾算法.首先基于暗通道引入了混合暗通道, 然后对混合暗通道进行映射处理, 从而得到大气耗散函数粗估计值; 利用导向滤波方法优化大气耗散函数粗估计值, 进而求解环境光值和初始传输图; 利用全变差正则化方法对初始传输图进行优化, 以解决其平滑性较差的问题.实验结果表明, 本文算法得到的去雾图像具有较高的清晰度, 对于大面积天空或白色物体区域也能实现良好的去雾效果.     

基于暗原色及入射光假设的单幅图像去雾

目的 雾是一种常见的天气状况,针对雾能使图像中的景物对比度降低、表面颜色退化的问题,提出一种基于入射光假设的单幅图像去雾方法。方法 首先利用全局暗原色进行初步去雾,从而使图像透射率处于[0,1]范围内;然后利用雾天光照均匀的特点以及Retinex的照度估计原理进行透射图的估计;最后利用透射图以及初步去雾图像得到复原图像。结果 与He算法、Fattal算法的对比实验结果显示,该算法获得的复原图像细节清晰,颜色自然。与引导滤波优化后的He去雾算法相比,本文算法速度提高了93%。结论 大量对比实验结果表明,本文算法能够显著恢复雾天降质图像,对于薄雾和浓雾同样有效,具有广泛的适用性,且算法原理简单。此外,本文算法也同样适用于灰度图。     

基于图像融合的快速单幅图像去雾算法

针对单幅雾霾图像中存在大面积明亮区域,暗通道先验失效、引导滤波算法去雾不彻底和时间复杂度较高的问题,提出了一种基于图像融合的快速单幅图像去雾算法.在大气散射模型的基础上,对大气光值进行区间估计;由暗通道先验法得到透射率的简单估计,由Retinex理论进行多尺度高斯卷积得到透射率的模糊估计,利用图像融合将两者进行像素级融合,得到透射率的精确估计;采用交叉双边滤波进行平滑处理并针对明亮区域修正透射率;对复原图像进行色调调整后得到最终图像.实验表明:算法不仅取得良好的去雾效果和较好的图像色彩,还有效降低了时间复杂度.     

基于图像分割的去雾算法

针对雾霾条件下,所得的单幅图像出现降质现象,因而对视觉效果要求高的图像进行复原具有必要性;基于图像分割的去雾算法以暗通道先验模型为基础对大气光矢量A值的求取和透射率t(x,y)的处理方法实现改进;首先对单幅图像进行阈值分割找到天空区域,在所获取的天空区域部分结合skyline算法,可以找到精确的大气光矢量A值;进而对初始透射率t(x,y)采用改进的约束最小二乘方滤波进行优化,得到优化透射率t₁(x,y),最后将所得的大气光矢量A值和优化透射率t₁(x,y)利用大气光传输物理模型复原;改进算法的去雾结果具备保留细致的边缘细节,同时具有高效的去除图像噪声能力;实验结果表明,与he方法相对比,改进去雾算法的处理时间大程度缩短的同时,图像效果得到了提升。     

基于暗原色先验的单幅图像快速去雾算法

针对雾天环境下图像清晰度降低以及色调偏移问题,提出一种基于暗原色先验的单幅图像快速去雾算法。首先使用灰度开运算代替最小值滤波得到粗略暗通道图,根据方差标记出雾天图像各个景深突变区的位置,并对突变区的暗原色值进行细化求解;其次求解出透射率的粗略估计并使用引导滤波来进行优化;然后使用一种自适应的容差机制对天空等明亮区域的透射率进行动态修正;最后利用大气散射模型复原出无雾图像。实验结果表明,与几种典型的图像去雾算法相比,所提算法具有较快的处理速度,同时得到的复原图像细节突出、色彩丰富。     

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.