A Parallel “String Matching Engine” for use in High Speed Network Intrusion Detection Systems

This paper describes a finite state machine approach to string matching for an intrusion detection system. To obtain high performance, we typically need to be able to operate on input data that is several bytes wide. However, finite state machine designs become more complex when operating on large input data words, partly because of needing to match the starts and ends of a string that may occur part way through an input data word. Here we use finite state machines that each operate on only a single byte wide data input. We then provide a separate finite state machine for each byte wide data path from a multi-byte wide input data word. By splitting the search strings into multiple interleaved substrings and by combining the outputs from the individual finite state machines in an appropriate way we can perform string matching in parallel across multiple finite state machines. A hardware design for a parallel string matching engine has been generated, built for implementation in a Xilinx Field Programmable Gate Array and tested by simulation. The design is capable of operating at a search rate of 4.7 Gbps with a 32-bit input word size.     

A real-time global stereo-matching on FPGA

An improved global stereo matching algorithm is implemented on a single FPGA for real-time applications. Stereo matching is widely used in stereo vision systems, i.e. objects detection and autonomous vehicles. Global algorithms have much more accurate results than local algorithms, but global algorithms are not implemented on FPGA since they rely over high-end hardware resources. In this implementation the stereo pairs are divided into blocks, the hardware resources are reduced by processing one block once. The hardware implementation is based on a Xilinx Kintex 7 FPGA. Experiment results show that the proposed implementation has an accurate result for the Middlebury benchmarks and 30 frames per second (fps) @1920 × 1680 is achieved.     

Reliability analysis of the rank transform for stereo matching

The rank transform is a nonparametric technique which has been recently proposed for the stereo matching problem. The motivation behind its application to this problem is its invariance to certain types of image distortion and noise, as well as its amenability to real-time implementation. This paper derives one constraint which must be satisfied for a correct match. This has been termed the rank constraint. Experimental work has shown that this constraint is capable of resolving ambiguous matches, thereby improving matching reliability. A novel matching algorithm incorporating the rank constraint has also been proposed. This modified algorithm consistently resulted in an increased percentage of correct matches, for all test imagery used. Furthermore, the rank constraint has been used to devise a method of identifying regions of an image where the rank transform, and hence matching outcome, is more susceptible to noise. Experimental results have shown that the errors predicted using this technique are consistent with the actual errors which result when images are corrupted with noise. Such a method could be used to identify matches which are likely to be incorrect and/or provide a measure of confidence in a match.     

基于可重构微服务器的高能效指纹比对方法

大规模指纹应用需要强大的后端指纹比对计算能力作为支撑.基于可重构微服务器(reconfigurable micro server, RMS)技术,提出一种软硬协同的高效指纹比对方法,该方法充分发挥可重构混合核心计算架构的优势,采用优化定制的硬件加速部件对指纹比对算法中的计算密集部分进行加速.复杂控制流和离散访存较多的算法部分则以软件形式在通用计算核心上高效执行.在单个RMS计算节点上完成了算法原型的实现并进行了详细测试.测试结果表明:单个RMS节点上的指纹比对性能约为105万次秒,功耗仅为5 W.与相关工作相比,该性能是单个X86集群节点的15.5倍;能效是X86集群节点的583倍,是基于Tesla C2075的GPU服务器的5.4倍.与单纯的FPGA平台相比,基于RMS技术的实现方法更具灵活性和可扩展性,是未来构建大规模指纹比对系统的一种高效的技术解决方案.     

一种单值区域的图形匹配算法

图形匹配是计算机视觉、机器人控制中一个重要问题。本文在文献[2]基础上,改进了其中不足,提出了一种单值区域的匹配算法,具有空间不变性,如：平移、旋转和尺度的不变性,而且鲁棒性很好、准确性很高。实验结果表明,对所有凸区域和许多凹区域图形的匹配都可行,而且速度也快。     

Rapid real-time generation of super-resolution hyperspectral images through compressive sensing and GPU

Recently, compressive sensing (CS) has offered a new framework whereby a signal can be recovered from a small number of noisy non-adaptive samples. This is now an active area of research in many image-processing applications, especially super-resolution. CS algorithms are widely known to be computationally expensive. This paper studies a real time super-resolution reconstruction method based on the compressive sampling matching pursuit (CoSaMP) algorithm for hyperspectral images. CoSaMP is an iterative compressive sensing method based on the orthogonal matching pursuit (OMP). Multi-spectral images record enormous volumes of data that are required in practical modern remote-sensing applications. A proposed implementation based on the graphical processing unit (GPU) has been developed for CoSaMP using computed unified device architecture (CUDA) and the cuBLAS library. The CoSaMP algorithm is divided into interdependent parts with respect to complexity and potential for parallelization. The proposed implementation is evaluated in terms of reconstruction error for different state-of-the-art super-resolution methods. Various experiments were conducted using real hyperspectral images collected by Earth Observing-1 (EO-1), and experimental results demonstrate the speeding up of the proposed GPU implementation and compare it to the sequential CPU implementation and state-of-the-art techniques. The speeding up of the GPU-based implementation is up to approximately 70 times faster than the corresponding optimized CPU.     

Refactoring pattern matching

Defining functions by pattern matching over the arguments is advantageous for understanding and reasoning, but it tends to expose the implementation of a datatype. Significant effort has been invested in tackling this loss of modularity; however, decoupling patterns from concrete representations while maintaining soundness of reasoning has been a challenge. Inspired by the development of invertible programming, we propose an approach to program refactoring based on a right-invertible language rinv—every function has a right (or pre-) inverse. We show how this new design is able to permit a smooth incremental transition from programs with algebraic datatypes and pattern matching, to ones with proper encapsulation, while maintaining simple and sound reasoning.     

3D Free-Form Object Recognition Using Indexing by Contour Features

We address the problem of recognizing free-form 3D objects from a single 2D intensity image. A model-based solution within the alignment paradigm is presented which involves three major schemes—modeling, matching, and indexing. The modeling scheme constructs a set of model aspects which can predict the object contour as seen from any viewpoint. The matching scheme aligns the edgemap of a candidate model to the observed edgemap using an initial approximate pose. The major contribution of this paper involves the indexing scheme and its integration with modeling and matching to perform recognition. Indexing generates hypotheses specifying both candidate model aspects and approximate pose and scale. Hypotheses are ordered by likelihood based on prior knowledge of pre-stored models and the visual evidence from the observed objects. A prototype implementation has been tested in recognition and localization experiments with a database containing 658 model aspects from twenty 3D objects and eighty 2D objects. Bench tests and simulations show that many kinds of objects can be handled accurately and efficiently even in cluttered scenes. We conclude that the proposed recognition-by-alignment paradigm is a viable approach to many 3D object recognition problems.     

A local method for contour matching and its parallel implementation

This paper presents a local approach for matching contour segments in an image sequence. This study has been primarily motivated by work concerned with the recovery of 3D structure using active vision. The method to recover the 3D structure of the scene requires to track in real-time contour segments in an image sequence. Here, we propose an original and robust approach that is ideally suited for this problem. It is also of more general interest and can be used in any context requiring matching of line boundaries over time. This method only involves local modeling and computation of moving edges dealing “virtually” with a contour segment primitive representation. Such an approach brings robustness to contour segmentation instability and to occlusion, and easiness for implementation. Parallelism has also been investigated using an SIMD-based real-time image-processing system. This method has been validated with experiments on several real-image sequences. Our results show quite satisfactory performance and the algorithm runs in a few milliseconds. Received: 11 December 1996 / Accepted: 8 August 1997     

普通话发音训练多级音素模板综合评价方法

提出了一种应用于普通话声韵母发音评价的多级音素模板综合评分法,该方法在单模板匹配的基础上,通过寻找汉语音素发音过程中的浊化、摩擦、爆破等特征,形成多个子模式,进行多模式匹配,最后给出加权评分。实验结果表明多级音素模板综合评分法有效地改善了汉语发音中几组相似音之间的区分度。也介绍了MFCC等语音特征提取、DTW模板匹配算法、基于聚类的模板训练以及综合加权评价机制的实现方法。     

基于模式匹配的软件架构恢复的研究

行业软件的开发常常是一个不断进化的过程。架构恢复对干软件维护和软件进化至关重要。本文介绍了软件架构恢复策略的框架、步骤和相关研究;描述了基于模式匹配进行软件架构恢复的方法,着重介绍了该架构恢复所基于的恢复环境、执行过程和模武匹配算法的具体实现。最后,给出了对Clips系统进行实验所得到的恢复结果的评估。     

On-line fingerprint verification

Fingerprint verification is one of the most reliable personal identification methods. However, manual fingerprint verification is incapable of meeting today's increasing performance requirements. An automatic fingerprint identification system (AFIS) is needed. This paper describes the design and implementation of an online fingerprint verification system which operates in two stages: minutia extraction and minutia matching. An improved version of the minutia extraction algorithm proposed by Ratha et al. (1995), which is much faster and more reliable, is implemented for extracting features from an input fingerprint image captured with an online inkless scanner. For minutia matching, an alignment-based elastic matching algorithm has been developed. This algorithm is capable of finding the correspondences between minutiae in the input image and the stored template without resorting to exhaustive search and has the ability of adaptively compensating for the nonlinear deformations and inexact pose transformations between fingerprints. The system has been tested on two sets of fingerprint images captured with inkless scanners. The verification accuracy is found to be acceptable. Typically, a complete fingerprint verification procedure takes, on an average, about eight seconds on a SPARC 20 workstation. These experimental results show that our system meets the response time requirements of online verification with high accuracy     

景象匹配算法在多DSP系统中的并行实现

灰度互相关匹配是一种有效的景象匹配算法,其具有适应性强和匹配精度高的特点。但互相关匹配的计算量很大,在实时性要求很高的精确末制导中,匹配速度往往很难满足要求。基于空间并行方法实现了互相关匹配算法的并行处理,通过不同数量处理器的并行处理实验,结果表明:空间并行方法具有很高的加速比和并行效率,是一种适合互相关匹配算法的有效的并行处理方法。当图像尺寸增大计算量增加时,可以采取增加处理器提高系统处理能力的办法使算法依然满足实时性要求。     

三维对象模型与地形的匹配方法研究

提出并详细论述了四点匹配的方法并对该方法中的悬空点计算、姿态突变等问题，给出了相应的解决方案．针对点、线、面匹配方法中存在的问题，各种方法的效率、质量、适用范围进行了比较，给出了虚拟环境中实现模型与地形匹配的方法选择的基本原则和实施步骤．     

基于极线几何的改进多约束图像立体匹配

针对计算机视觉和模式识别领域基本而重要的问题--立体匹配,提出了一种基于极线几何、结合特征匹配与区域匹配、视差梯度约束等多约束立体匹配算法,实现图像快速准确匹配.该算法将现有的基于特征和基于窗口匹配两种方法相结合,并加入视差梯度等约束条件,有效弥补了单一匹配算法的不足,同时增强了算法适应性.实验表明,该算法具有更高的求解质量和求解效率,可以满足双目立体视觉系统的需要.     

基于空间分块的图像匹配多DSP系统实现

图像匹配是图像处理的一个重要分支,其算法运算量大。针对图像互相关匹配算法具有较强的并行特性,提出空间分块技术对图像进行分块以及算法进行任务均衡分解,并将分割的图像数据通过FPGA生成的四块双口RAM空间进行数据存储并传输给多DSP进行图像NCCF值计算,实现快速图像匹配。实验证明该系统实现方案可行,具有较强的实际应用效果。     

边缘增强图像互相关模板匹配的并行架构

基于归一化互相关测度(NCC)的模板匹配已经在图像处理领域得到了广泛的应用。对图像进行边缘检测然后进行模板匹配,可充分利用图像的空间相关性,锐化模板匹配结果的相关峰,提高匹配的准确度,可以获得更高的定位精度。为了有效提高定位精度,考虑到导弹制导系统的算法实时性、体积以及为适应战场不同任务阶段采用不同匹配策略的灵活性要求,基于FPGA,通过结合Sobel边缘检测,进一步改进了提出的图像归一化互相关模板匹配高速并行实现架构。对边缘检测前后图像模板匹配的仿真比较结果表明,边缘检测处理可有效锐化相关峰;基于Altera的FPGA芯片EP2S90和开发软件Quartus Ⅱ 8.0的并行实现架构功能与时序仿真及在实际目标识别系统中的应用表明,这种方案可有效地提高系统的运算速度和定位精度,FPGA实现本身也进一步缩小了系统的体积。     

Real-Time Feature Matching in Image Sequences for Non-Structured Environments. Applications to Vehicle Guidance

This paper describes an integrated vehicle control system with visual feedback. A general-purpose, low-level feature matching method, able to work in real time without any strict assumptions on the environment structure or camera parameters, generates low-level matching results, which are used as source of data for applications like mobile object tracking, among others. A generalized predictive path-tracking control approach keeps the vehicle on the trajectory defined by the moving target. In the low-level matching process, block-based features (windows) are selected and tracked along a stream of monocular images; least residual square error and similarity between clusters of features are used as constraints to select the right matching pair between multiple candidates. Real-time performance is achieved through optimized algorithms and a parallel DSP-based multiprocessor system implementation. Object detection and tracking is motion-based, and does not require a predefined model of the target. The integrated control system has been tested on the ROMEO-3R experimental vehicle.     

自动孔板印刷机中图像检测系统的设计与实现

设计与实现了自动孔板印刷机中印刷图像质量检测系统。该系统主要包括孔板印刷中多路印刷图像的获取、特征的提取和匹配以及质量监控处理等功能模块。在RG Chromaticity空间中采用模板匹配的方法设计了相关的算法,实现了对印刷图像的错位、漏印、渗溢以及颜色不均等质量因素的快速实时检测,并成功地应用于自动丝网印刷设备中。经过测试和运行取得了良好的质量监控效果和经济效益。     

Practical solution using a new approach to robot vision

A system has been devised for development and testing in robot vision applications. The hardware and software of the system are described. Keyboard manufacturing is taken as a typical example of robot vision applications. For this example, an account is given of the four main stages in a development and implementation programme: defining the requirements of the application; matching these to the vision system; developing the application software; integrating and installing the system. Further applications of robot vision are suggested.