喷墨印刷中重影检测及修复技术

重影是喷墨印刷中影响印刷质量的主要问题之一,尤其是在彩色文字印刷中,重影的出现将会导致文字模糊,甚至影响辨识。通过打印特殊设计的检测图,运用数字图像处理的方法,精确识别每个喷嘴喷射的墨滴的着墨点位置,从而计算出重影偏移量。根据所得偏移量参数,提出了基于网点图调整的重影修复方法,该方法与硬件设备及挂网算法独立。实验结果表明,提出的方案检测精度高,重影修复效果好,并且能够满足高速印刷的实时性要求。     

一种去除运动目标重影的图像镶嵌方法研究

针对图像镶嵌过程中如果图像序列中存在运动目标就会引起重影的问题,文中提出了一种新的去除运动目标重影的图像镶嵌方法。算法首先对视频图像进行了运动分割,在图像匹配阶段采用边缘特征点进行匹配,并由马尔可夫随机场模型生成运动目标的二值模板,剔除掉运动目标二值模板上的边缘点,从而保证图像匹配的准确率。在镶嵌阶段使用活动轮廓模型生成一条最优镶嵌线,产生的镶嵌线充分考虑了图像的边缘特征和梯度信息,确保了镶嵌后图像两边纹理差异更小。从连续视频帧中选取多帧图像进行实际的图像镶嵌,实验结果表明文中算法取得了较好的效果。     

一种光学显微自动聚焦系统设计与实现

针对普通CCD拍摄的低对比度生物样品图像,设计并实现了一种以PC机为控制核心的光学显微镜自动聚焦系统。系统采用弹性联轴器与显微镜调焦轴直接耦合的方式,结合细分驱动,有效地消除了传动机构的回程差,提高了聚焦控制精度。在对几种常用图像清晰度评价算子进行分析的基础上,证实了图像自相关算子是评价低对比度生物样品图像清晰度的有效算法。实验结果表明,该系统自动聚焦的准确度和实时性基本上满足生物学研究的需要。     

一种印刷电路板缺陷图像边缘信息提取方法

为了较好地提取印刷电路板缺陷图像边缘信息,提出了基于二阶曲线拟合、模式聚类与阈值比较法相结合的印刷电路板缺陷图像边缘信息提取方法。首先分析了最小二乘法拟合的基本原理;然后在此基础上提出了采用二阶曲线拟合法来设定阈值进行拟合得到大致的图像边缘,并分析了其基本原理;最后在模式聚类基础上利用阈值比较法选择适当阈值截取拟合曲线得到图像边缘点、去除噪声边缘点,连接各个图像边缘点可得到缺陷图像的边缘信息。用由显微镜及CCD获取的4幅印刷电路板缺陷图像进行了实验;从实验主观效果看,用该方法提取出图像边缘信息的效果较好,图像边缘比较连续,噪声点极少;从实验客观效果评价看,用该方法所得到的图像边缘信息熵较大。实验结果表明,该方法结合了二阶曲线拟合、模式聚类与阈值比较法优点,可较好地提取出印刷电路板缺陷图像的边缘信息。     

一种基于RPCA的图像聚焦区域检测方法

阁像聚焦区域检测是图像融合、计算机视觉等领域中的一个重要研究方向．聚焦区域属于图像中的显著性区域,仉人部分娩著性区域愉测算法在提取图像聚焦区域是存在一定的问题,不能进行准确分辨和提取．针对现有方法的不足,该文利用近来受到广泛关注的RPCA（Robust Principal Component Analysis）分解技术,提取出能有效表征图像聚焦区域的稀疏特征矩阵,并结合多区域图像分割技术获得聚焦区域．实验结果证明了该文所提方法存获取聚焦区域上的有效性,此外,该文指出基于RPCA的图像分解技术有着广泛的用途．     

激光打印机重影的解决与预防

近来,办公所用的激光打印机有重影现象（如右图）,十分影响美观和阅读。激光打印机打印时为什么会出现重影？该如何解决与预防呢？以下笔者对此略做介绍     

一种摄像头自动聚焦方法及硬件实现

提出了一种基于数字图像处理技术实现自动聚焦的方法,给出了一种改进的灰度差分法作为图像聚焦是否清楚的评价函数。对图像质量进行比较,根据比较结果由单片机驱动镜头到达聚焦点,实现自动聚焦。     

显微镜一种新的自动聚焦算法

在开发普通光学显微镜自动聚焦系统的过程中,超初作者采用图像灰度熵和灰度方差这两种常用的显微镜聚焦算法,但实际应用效果不很理想。经检验发现了两种算法的一些不足之处,并针对这些不足点加以改进,进而提出了灰度差分绝对值之和算法。经实际聚焦过程中的对比实验,证明了新算法在聚焦可靠性、聚焦速度及聚焦结果等方面都具有一定的优越性。     

一种综合的SAR图像边缘检测方法

针对合成孔径雷达图像中斑点噪声的特性,基于中值滤波方法,并结合Ratio算子、Canny算子和双阈值连接三种处理方法,提出一种综合的边缘检测算法。实验结果表明,与传统算法比较,该算法克服了边缘方向量化带来的直线断裂,边缘定位准确,显著提高了边缘检测正确率,并对噪声有抑制作用,从而取得了良好的检测效果。     

一种综合的SAR图像边缘检测方法

针对合成孔径雷达图像中斑点噪声的特性，基于中值滤波方法，并结合Ratio算子、Canny算子和双阈值连接三种处理方法，提出一种综合的边缘检测算法。实验结果表明，与传统算法比较，该算法克服了边缘方向量化带来的直线断裂，边缘定位准确，显著提高了边缘检测正确率，并对噪声有抑制作用，从而取得了良好的检测效果。     

A focus checking technique for image analysis systems

The paper describes a method of checking the accuracy of focus of images scanned with a raster scanner, by means of direct analysis of the data from a single scan. The parameter used is a measure of the high frequency response of the system to sharp edges in the image, and is obtained by comparing entries of tables of density differences between adjacent and near-adjacent pixels along scanlines. The technique has been incorporated into an autofocussing module of an automated cytology prescreening system, and has been found to give adequate warning of focus errors when scanning a wide range of normal and abnormal cytology specimens.     

OpenCV在印刷质量检测系统中的应用

本文依据印刷质量检测系统的要求,通过分析用于数字图像处理的开放源代码的计算机视觉类库OpenCV的特点与功能,分析了OpenCV在印刷质量检测系统中的可行性。提出OpenCV可以用于印刷质量检测系统的开发。     

基于开源LAMP架构的Web打印技术

通过对现有B/S架构打印方法进行分析对比,针对它们的缺陷提出了一种基于开源LAMP架构的跨平台、精确、有效的Web打印新技术,并详细介绍了其原理,最后给出了具体的实现方法.     

On an equivalence checking technique for algebraic models of programs

In the paper, the equivalence checking problem for program schemas in balanced semigroup models of programs is studied. A method for constructing algorithms to resolve this problem is proposed in the case where a semigroup model of programs possesses the left cancellation property h ₁ h ₂ = h ₁ h ₃ ? h ₂ = h ₃. The equivalence checking problem is shown to be decidable in time that polynomially depends on size of the schema being checked if the balanced semigroup model of programs possesses additionally the right cancellation property h ₂ h ₁ = h ₃ h ₁ ? h ₂ = h ₃.     

Improving data accuracy: Selecting the best data checking technique

Data entry errors can have catastrophic effects on the results of a statistical analysis. Therefore, researchers often spend considerable effort checking their data. This paper compared the effectiveness of three data checking methods – double entry, read aloud, and visual checking – using the types of data and data entry personnel that are typically used in psychological research. To compare these techniques, we created 20 data sheets and entered them into the computer. Next, we deliberately introduced errors into this data set. Participants’ job was to locate and correct these errors.     

检查存储变动的入侵检测技术研究

大部分的入侵行为都会引起被入侵主机的存储变动,因此检查存储变动是一种有效的入侵检测方法。校验和方法与基于存储的入侵检测技术是两种重要的检查存储变动的入侵检测技术。综述和比较了这两种技术。     

Fabrication of electrochemical carbon-based microelectrodes using electrohydrodynamic jet printing technique

Microsystem Technologies - Due to unique advantages, carbon is widely used as electrode material for electrochemical sensors. In this paper, an efficient method of combining the electrohydrodynamic...     

A correspondence between type checking via reduction and type checking via evaluation

We describe a derivational approach to proving the equivalence of different representations of a type system. Different ways of representing type assignments are convenient for particular applications such as reasoning or implementation, but some kind of correspondence between them should be proven. In this paper we address two such semantics for type checking: one, due to Kuan et al., in the form of a term rewriting system and the other in the form of a traditional set of derivation rules. By employing a set of techniques investigated by Danvy et al., we mechanically derive the correspondence between a reduction-based semantics for type checking and a traditional one in the form of derivation rules, implemented as a recursive descent. The correspondence is established through a series of semantics-preserving functional program transformations.     

A framework for checking proofs naturally

We propose a logical framework, called Natural Framework (NF), which supports formal reasoning about computation and logic (CAL) on a computer. NF is based on a theory of Judgments and Derivations. NF is designed by observing how working mathematical theories are created and developed. Our observation is that the notions of judgments and derivations are the two fundamental notions used in any mathematical activity. We have therefore developed a theory of judgments and derivations and designed a framework in which the theory provides a uniform and common play ground on which various mathematical theories can be defined as derivation games and can be played, namely, can write and check proofs. NF is equipped with a higher-order intuitionistic logic and derivations (proofs) are described following Gentzen’s natural deduction style. NF is part of an interactive computer environment CAL and it is also referred to as NF/CAL. CAL is written in Emacs Lisp and it is run within a special buffer of the Emacs editor. CAL consists of user interface, a general purpose parser and a checker for checking proofs of NF derivation games. NF/CAL system has been successfully used as an education system for teaching CAL for undergraduate students for about 8 years. We will give an overview of the NF/CAL system both from theoretical and practical sides.