基于曲波域的指纹预处理研究

研究了一种基于曲波域的指纹图像预处理方法。首先将指纹图像在曲波域中分解,然后用Gabor滤波器来处理粗尺度系数,这些系数是原图像的近似值;同时,在细尺度系数上使用软阈值函数减少沿着脊线方向的噪声。再将重构以后的图像二值化,最后使用基于模板的脉冲耦合神经网络(PCNNs)细化算法细化二值图像,得到指纹的骨架图像。实验结果表明,该方法优于传统的基于Gabor滤波器的指纹图像预处理方法。     

基于脊向指纹滤波算法

滤波技术是指纹预处理中的关键步骤.本文提出了一种基于脊向指纹滤波预处理方法.首先利用改进后的极值滤波器对指纹图像进行滤波,再用本文所提出的脊向滤波器对结果进行处理.实验结果验证了此方法的有效性.     

指纹增强算法研究

文章主要研究指纹图像的增强算法,在文中改进了基于STFT(Short Time Fourier Transform)的指纹增强算法,有效的去除了使用STFT增强后图像当中存在的块效应;并且本文提出了一种融合自适应滤波器和Gabor滤波器的增强方法,克服了自适应滤波器断裂脊线连接能力较差和Gabor滤波器分离粘连脊线能力较弱的缺点.实验结果表明这两种方法取得了较好的滤波增强效果.     

指纹旋转情况判定

指纹旋转对社保指纹自主识别系统的性能有负面影响。通过对旋转指纹的研究,采取基于细化二值指纹图像,直接根据录入的指纹图像就可以判定出指纹的旋转情况,而不需要与库存模板进行匹配。它们能给出提示,引导用户采集到不发生旋转的指纹图像。以此解决旋转指纹对指纹识别系统性能的负面影响。文中给出了提取指纹中心点的算法,提出了一种新的基于细化二值指纹图像的脊线跟踪提取算法。     

一种有效的指纹图像细化算法

OPTA方法是一个经典的指纹图像细化方法,针对OPTA法的不足提出改进的OPTA方法能够得到完全细化的指纹图像,细化后图像纹线扭曲小.但是改进的OPTA方法还存在细化后的图像容易产生毛刺的不足,为此提出一组改进模板,即在改进的OPTA模板的基础上增加一组去除毛刺的模板.实验表明,通过该算法得到的细化指纹图像在保持连通性的基础上光滑无毛刺,取得了更为理想的细化结果.     

一种基于指纹细化图的脊线追踪算法

指纹属性是指纹的重要特征,脊线追踪是进行指纹属性拾取的前提。本文提出了一种在细化后的指纹图像上实现脊线追踪的算法,该算法以细节端点和叉点为起始点,沿着脊线的方向逐点进行跟踪,从而遍历指纹细化图中所有脊线。实验结果表明,该算法对细化后的指纹图像具有较好的脊线追踪效果,从而为指纹属性的拾取打下了良好的基础。     

基于8方向脊向滤波器的指纹预处理方案

在自动指纹识别系统中,对时间复杂度高的指纹图像预处理算法进行研究,为了有效地去除指纹图像中的噪声,提高识别速度以应用于实时系统,提出了一种基于8方向脊向滤波器的指纹预处理方案。该方案在求取点方向图时以方向逼近法为基础,引入均值滤波的思想以降低图像中噪声的影响,获取一致性更好、性能更稳定的点方向图;然后根据脊向滤波器的设计原理,优化设计了一组对应于指纹图像方向信息的8方向脊向滤波器模板;最后运用查表法,对于指纹图像中的每个像素点选取与其方向信息相应的滤波器模板进行图像增强。在FVC2004公布的指纹图像数据库DB1_B上,按照FVC2004测试标准所做的试验结果表明,本文所提方案简单快速有效,能够应用于实时的自动指纹识别系统。      

Linux系统下指纹图像处理系统的研究与实现

基于指纹图像处理准确性高、实时性强等实际要求,介绍了一种指纹图像处理方法.Linux系统下用基于fps200芯片的指纹采集系统采集指纹图像,并用QT编程实现了指纹图像采集、处理的整个过程.通过研究,提出了满足要求的方向增强以及细化算法.整个处理过程实时性强,处理后指纹图像细节特征保存较好,可以胜任AFIS的前期工作.     

基于简单方向场的指纹中心点快速检测方法

指纹中心点周围分布着大量的可以直接识别的特征信息,本文提出了一种检测指纹中心点的快速简单的算法,利用基于块的指纹方向场,二值化后得到简单方向场,基于这种简单方向,可以定位指纹奇异点的所在的块,在由指纹预处理后细化图像,可以快速精确定位指纹中心点所在的位置。     

指纹图像的预处理算法

提出了基于方向特性的指纹预处理算法,包括前景/背景提取、平滑、二值化、二值滤波、细化5部分。该算法通过计算指纹方向图对指纹图像进行分割,依据方向场实现二值化,最后采用骨架提取技术细化指纹。这套算法成功减少了原特征的丢失和伪特征的增加。实验结果显示,该算法能够去除噪声,得到较高质量的指纹图像。     

Development of the readout system for waveguide multilayer optical card

Waveguide multilayer optical card （WMOC） is a novel storage device of three-dimensional optical information. An advanced readout system fitting for the WMOC is introduced in this paper. The hardware mainly consists of the light source for reading, WMOC, motorized stages addressing unit, microscope imaging unit, CCD detecting unit and PC controlling ＆ processing unit. The movement of the precision motorized stage is controlled by the computer through Visual Basic （VB） language in software. A control panel is also designed to get the layer address and the page address through which the position of the motorized stages can be changed. The WMOC readout system is easy to manage and the readout result is directly displayed on computer monitor.     

Nanoimprint Lithography -A Next Generation High Volume Lithography Technique

IntroductionNanoimprint Lithography is a well-acknowl-edged low cost, high resolution, large area pattern-ing process. It includes the most promising methods,high-pressure hot embossing lithography (HEL) [2],UV-cured imprinting (UV-NIL) [3] and micro contactprinting (m-CP, MCP) [4]. Curing of the imprintedstructures is either done by subsequent UV-lightexposure in the case of UV-NIL or by cooling downbelow the glass transition temperature of the ther-moplastic material in case of HEL…     

Collinear phase-matching study of terahertz-wave generation via difference frequency mixed in GaAs and Inp

The collinearly phase-matching condition of terahertz-wave generation via difference frequency mixed in GaAs and InP is theoretically studied. In collinear phase-matching, the optimum phase-matching wave hands of these two crystals are calculated. The optimum phase-matching wave bands in GaAs and lnP are 0.95-1.38μm and 0.7-0.96μm respectively. The influence of the wavelength choice of the pump wave on the coherent length in THz-wave tuning is also discussed. The influence of the temperature alteration on the phase-matching and the temperature tuning properties in GaAs crystal are calculated and analyzed. It can serve for the following experiments as a theoretical evidence and a reference as well.     

Effects of the alloy compositions on the phonon-polaritons in ternary mixed crystals

Composition dependence of bulk and surface phonon-polaritons in ternary mixed crystals are studied in the framework of the modified random-element-isodisplacement model and the Bom-Huang approximation. The numerical results for Several Ⅱ - Ⅵ and Ⅲ- Ⅴ compound systems are performed, and the polariton frequencies as functions of the compositions for ternary mixed crystals AlxGa1-xAs, GaPxAS1-x, ZnSxSe1-x, GaAsxSb1-x, GaxIn1-xP, and ZnxCd1-xS as examples are given and discussed. The results show that the dependence of the energies of two branches of bulk phonon-polaritons which have phonon-like characteristics, and surface phonon-polaritons on the compositions of ternary mixed crystals are nonlinear and different from those of the corresponding binary systems.     

Influence of PVK ： NPB hole transporting layer on the characteristics of organic light-emitting devices

A doping system consisting of NPB and PVK is employed as a composite hole transporting layer （CHTL）. By adjusting the component ratio of the doping system, a series of devices with different concentration proportion of PVK ： NPB are constracted. The result shows that doping concentration of NPB enhances the competence of hole transporting ability, and modifies the recombination region of charge as well as affects the surface morphology of doped film. Optimum device with a maximum brightness of 7852 cd/m^2 and a power efficiency of 1.75 lm/W has been obtained by choosing a concentration proportion of PVK ： NPB at 1：3.     

New insert layer structure OLEDs

An insert layer structure organic electroluminescent device（OLED） based on a new luminescent material （Zn（salen）） is fabricated. The configuration of the device is ITO/CuPc/NPD/Zn（salen）/Liq/LiF/A1/CuPc/NPD/Zn（salen）/Liq/LiF/A1. Effective insert electrode layers comprising LiF（1nm）/Al（5 nm） are used as a single semitransparent mirror, and bilayer cathode LiF（1 nm）/A1（100 nm） is used as a reflecting mirror. The two mirrors form a Fabry-Perot microcavity and two emissive units. The maximum brightness and luminous efficiency reach 674 cd/m^2 and 2.652 cd/A, respectively, which are 2.1 and 3.7 times higher than the conventional device, respectively. The superior brightness and luminous efficiency over conventional single-unit devices are attributed to microcavity effect.     

Analysis of error performance on Turbo coded FDPIM

Due to variable symbol length of digital pulse interval modulation（DPIM）, it is difficult to analyze the error performances of Turbo coded DPIM. To solve this problem, a fixed-length digital pulse interval modulation（FDPIM） method is provided. The FDPIM modulation structure is introduced. The packet error rates of uncoded FDPIM are analyzed and compared with that of DPIM. Bit error rates of Turbo coded FDPIM are simulated based on three kinds of analytical models under weak turbulence channel. The results show that packet error rate of uncoded FDPIM is inferior to that of uncoded DPIM. However, FDPIM is easy to be implemented and easy to be combined, with Turbo code for soft-decision because of its fixed length. Besides, the introduction of Turbo code in this modulation can decrease the average power about 10 dBm, which means that it can improve the error performance of the system effectively.     

A method for calculating the center position of collimated light

It is a key problem to accurately calculate beam spots＇ center of measuring the warp by using a collimated laser. A new method, named double geometrical center method （DGCM）, is put forward for the first time. In this method, a plane wave perpendicularly irradiates an aperture stop, and a charge couple device （CCD） is employed to receive the diffraction-beam spots, then the geometrical centers of the fast and the second diffraction-beam spots are calculated respectively, and their mean value is regarded as the center of datum beam. In face of such adverse instances as laser intension distributing defectively, part of the image being saturated, this method can still work well. What＇s more, this method can detect whether an unacceptable error exits in the courses of image receiving, processing and calculating. The experimental results indicate the precision of this method is high.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.