基于版面的拍照文档图像倾斜校正

文档图像版面十分复杂,建立一个较为通用的文档图像倾斜校正算法是很困难的。因此提出了基于版面的文档图像倾斜自动校正算法,并且对经典的霍夫变换检测直线的方法进行了改进,最后采用最小距离法对这些直线进行拟合,避免了因利用传统的最小二乘法拟合直线所带来的缺点。针对不同的文档版面采用相应的倾斜校正策略,实验表明该方法具有适应性强、倾斜校正速度快和精度高的特点。     

Accelerated Hough transform using rectangular image decomposition

A novel fast method for evaluating the Hough transform is proposed, which can be used to accelerate detection of prevalent linear formations in binary images. An image is decomposed using rectangular blocks and the contribution of each whole block to the Hough transform space is evaluated, rather than the contribution of each image point. The resulting acceleration in the calculation of the Hough transform field is demonstrated in two image processing experiments related to object axis identification and skew detection of digitised documents     

端面不透光的PDMS微柱阵列制备与图像处理方法研究

细胞可对外界施加力的作用，从而感知外界环境并做出力学响应。聚二甲基硅氧烷（PDMS）微柱阵列被广泛应用于细胞力测量，通过测量微柱顶面在细胞力作用下的位移量，获得细胞力的大小及方向。然而，由于PDMS微柱的高透明度，当利用明场显微图像进行图像处理计算微柱位移量时，提取微柱端面质心的算法较为复杂。提出了一种利用磁珠修饰微柱端面使其不透光的方法，以降低图像处理算法复杂度，同时提高微柱位置的识别精度。磁珠在外界磁场作用下被引入模具，向模具中浇铸PDMS后，得到端面嵌有磁珠的不透光PDMS微柱。修饰过后的微柱，其端面会在倒置显微镜下形成实心圆形图案，可以直接用regionprops函数计算出实心圆形图案的质心；未经修饰的微柱，在倒置显微镜下形成环形图案，需要用运算更为复杂的霍夫变换来计算环形图案质心。实验结果表明:该PDMS微柱修饰方法能使微柱端面与基底的对比度得到很大提高，因此在提取端面质心时，不需要用到霍夫变换，减小了图像处理中算法的复杂度，并且提高了微柱定位的精度。     

用于HRR雷达在非高斯杂波中进行起伏目标检测的基于Hough变换的两种算法之比较

在HRR雷达中,当目标尺寸大于雷达波长和雷达距离分辨单元时,在连续扫描过程中从目标不同散射中心返回的目标回波会产生不同的方向图,使传统杂波抑制方法无效。提出采用Hough变换来解决这个问题。Hough变换是一种在图像中识别曲线的著名变换。比较了两种基于Hough变换的雷达检测算法,一是将数据空间中的点映射到ρ-θ空间中的曲线的传统模式,另一种模式采用斜率-截距参数空间Hough变换。斜率-截距模式的效率通过仿真进行验证。与传统模式相比,Hough变换的斜率-截距模式的性能更好。针对非起伏目标及四种Swerling类目标,研究了在瑞利分布、Weibull分布、对数正态分布和K分布杂波下,Hough变换检测器的斜率-截距模式对HRR雷达信号的检测性能。还研究了目标速度和脉冲数的影响。通过Monte-Carlo仿真对Hough变换检测器的目标检测性能进行了分析。     

Exploiting Inherent Parallelisms for Accelerating Linear Hough Transform

Accelerating Hough transform in hardware has been of interest due its popularity in real-time capable image processing applications. In most existing linear Hough transform architectures, an m times medge map is serially read for processing, resulting in a total computation time of at least m² cycles. In this paper, we propose a novel parallel Hough transform computation method called the Additive Hough transform (AHT), wherein the image is divided using a k times k grid to reduce the total computation time by a factor of k². We have also proposed an efficient implementation of the AHT consisting of a look-up table (LUT) and two-operand adder arrays for every angle. Techniques to condense the LUT size have also been proposed to further reduce area utilization by as much as 50%. Our investigations based on employing an 8 times 8 grid shows a 1000 times speedup compared to existing architectures for a range of image sizes. Area-time trade-off analysis has been presented to demonstrate that the area-time product of the proposed AHT-based implementation is at least 43% lower than other implementations reported in the literature. We have also included and characterized a hierarchical addition step in order to generate a global accumulation space equivalent to that of the conventional HT. It is shown that the proposed implementation with the hierarchical addition step remains superior to other methods in terms of both performance and area-time product metrics. Finally, we show that the proposed solution is equally efficient when applied on rectangular images.     

一种适合多频连续波体制雷达的航迹起始算法

作为多目标航迹处理中的首要问题,航迹起始的好与坏直接影响着后续航迹的处理.现有的航迹起始算法主要分为顺序处理技术和批处理两大类,包括直观法、逻辑法、Hough变换法、修正的Hough变换法等.本文对几种航迹起始算法的性能进行了仿真分析,并在此基础上研究了一种基于逻辑法的航迹起始算法,工程应用表明这是一种适用于多频连续波体制雷达的航迹起始算法.     

New method of bad points elimination based on Hough transform

In experimental tests, besides data in range of allowable error, the experimenters usually get some unexpected wrong data called bad points. In usual experimental data processing, the method of bad points exclusion based on automatic programming is seldom taken into consideration by researchers. This paper presents a new method to reject bad points based on Hough transform, which is modified to save computational and memory consumptions. It is fit for linear data processing and can be extended to process data that is possible to be transformed into and from linear form; curved lines, which can be effectively detected by Hough transform. In this paper, the premise is the distribution of data, such as linear distribution and exponential distribution, is predetermined. Steps of the algorithm start from searching for an approximate curve line that minimizes the sum of parameters of data points. The data points, whose parameters are above a self-adapting threshold, will be deleted. Simulation experiments have manifested that the method proposed in this paper performs efficiently and robustly.     

Study on Detection and Recognition of Speed Signs

Speed sign detection and recognition are the important part of the driving assistant systems.Combining gradient-based random Hough transform with BP network,a method is proposed to detect and recognize speed signs.Firstly,the gradient-based random Hough transform is used to detect and locate the speed signs.Then four contour features of the ’digit’ inside the speed signs are extracted and recognized using the method of BP network.The results show that this method can detect and recognize the speed signs accurately and efficiently.     

并行Hough 变换航迹起始

Hough 变换作为一种批处理航迹起始方法,混淆了传感器量测数据的时序信息,难以克服单次扫描数据的累积效应。该文通过改变Hough 变换处理结构和计数器累加方式,提出了一种并行处理结构的Hough 变换航迹起始算法。该算法利用Hough 变换将不同时刻的量测集合分别映射到参数空间,继而将空间中具有相同索引的各次累加结果构成累加向量;再根据建立的参数空间累加规则,利用滑窗法来确定累积矩阵的输出,最后通过门限检测实现航迹起始判决。对密集杂波环境下不同扫描周期下的航迹起始问题进行了仿真验证,结果表明了并行Hough变换起始算法的有效性。      

Recognition Method of Aircraft Axis Direction Based on Morphological Skeleton and Hough Transform

Because of the limit of angle of view（AOV） of IR imaging seeker during the approach of missile and target, the detector can only get the partial image sequence of aircraft nose after ＂lose point＂. Recognizing the axis direction on the basis of partial IR image sequence is a key issue of the advanced IR imaging guide airto-air missile faced. In this paper, a recognition method was proposed based on the morphological skeleton and modified Hough transform, and this method can recognize correctly the axis direction of aircraft nose in different poses during missile-target encounter. Firstly, the morphological skeleton transform was used for the extraction of skeleton features. Secondly, the modified Hough transform was used for the straight-lines detection. Finally, According to the relations between aircraft nose and axis and invariant of nose features in high-speed IR image sequence, the axis direction can be detected and calculated. Experimental results indicate that the method is feasible and effective, and the precision of axis direction recognized can meet the requirement of accurate burst control of GIF fuze.     

基于Hough变换的瞳孔识别方法研究与实现

研究了一种改进的基于Hough变换圆检测的瞳孔识别方法。直接利用Hough变换圆检测进行瞳孔识别准确度低、运算量大,为此,本文提出了改进的识别方法。在实现Canny边缘检测的基础上,利用Hough变换进行求解时,限定检测的半径范围,在此范围内,根据参数空间圆的方程,求出对应的圆心坐标,得到最佳拟合圆,最终实现瞳孔识别以及中心点定位。在vc++6.0开发平台下,对150幅图像进行瞳孔识别检测实验,结果显示,直接利用Hough变换检测方法的准确率为70.7%,平均速度为1 s;本方法的准确率为94%,平均速度为0.45 s,可见相较于直接利用Hough变换进行瞳孔识别,本文方法在识别准确率和识别速度方面均有显著提高。结果表明,此方法能够快速而准确地进行瞳孔识别以及中心点定位。     

浅地层探地雷达波速测量方法的研究

波速的测量在探地雷达的研究中一直是一个至关重要的课题,尤其是对地下目标进行定位和成像时;本文针对浅地层探地雷达接收信号的特征,抛弃传统的过零点检测和其他的边缘轮廓检测方法,提出用极值进行边缘轮廓检测的方法,从而对目标的提取更准确并且有较少的数据,减少了霍夫变换的计算量;通过对霍夫变换算法的分析,针对传统霍夫变换的缺点,提出了一种加FIR低通滤波器的改进霍夫变换;同时应用算法对实测数据进行了计算,证明所提算法比传统的霍夫变换方法有更高的测速准确度.     

A NEW METHOD OF BAD POINTS ELIMINATION BASED ON HOUGH TRANSFORM

In experimental tests,besides data in range of allowable error,the experimenters usually get some unexpected wrong data called bad points. In usual experimental data processing,the method of bad points exclusion based on automatic programming is seldom taken into consideration by researchers. This paper presents a new method to reject bad points based on Hough transform,which is modified to save computational and memory consumptions. It is fit for linear data processing and can be extended to process data that is possible to be transformed into and from linear form; curved lines,which can be effectively detected by Hough transform. In this paper,the premise is the distribution of data,such as linear distribution and exponential distribution,is predetermined. Steps of the algorithm start from searching for an approximate curve line that minimizes the sum of parameters of data points. The data points,whose parameters are above a self-adapting threshold,will be deleted. Simulation experiments have manifested that the method proposed in this paper performs efficiently and robustly.     

海天背景下红外小目标检测的背景抑制及海天线检测方法

针对复杂海天背景下红外弱小目标难以检测与识别的问题,提出了基于海天线检测实现远距离弱小目标识别的方法。该方法对采集到的红外图像进行相关处理。通过用多级小波变换方法抑制背景杂波噪声提高目标信杂比;然后使用多方向Gabor滤波融合方法增强海天线边缘,并通过霍夫变换方法实现海天线定位和检测;最后通过定位海天线确定海天线附近区域的目标搜寻范围,缩小目标点潜在区,从而提高弱小目标在海天背景下的检测和识别概率。     

Automated cell nuclei segmentation for breast fine needle aspiration cytology

Breast cancer detection and segmentation of cytological images is the standard clinical practice for the diagnosis and prognosis of breast cancer. This paper presents a fully automated method for cell nuclei detection and segmentation in breast cytological images. The images are enhanced with histogram stretching and contrast-limited adaptive histogram equalization (CLAHE). The locations of the cell nuclei in the image are detected with circular Hough transform (CHT) and local maximum filtering. The elimination of false positive findings (noisy circles and blood cells) is achieved using Otsu’s thresholding method and fuzzy C-means clustering technique. The segmentation of the nuclei boundaries is accomplished with the application of the marker controlled watershed transform in the gradient image, using the nuclei markers extracted in the detection step. The proposed method is evaluated using 92 breast cytological images containing 11,502 cell nuclei. Experimental evidence shows that the proposed method has very effective results even in the case of images with high degree of blood cells, noisy circles.     

基于Hough变换的红外序列图像点目标跟踪方法

针对红外序列图像中点目标成像质量较差、跟踪困难等问题,利用Hough变换算法的抗噪性,并根据测量图像的具体特点,对算法的计算量进行了优化.通过将三维空间Hough变换降为二维,提出了一种基于Hough变换的红外序列图像点目标跟踪方法.实验结果表明,该方法对部分缺损及大小变化的目标都能够实现稳定跟踪,提高了红外目标跟踪的...     

基于视觉的微细对接焊缝检测方法

本文将机器视觉和图像处理技术融入到紧密对接焊缝的检测系统中,提出一种采用LED光源照明的焊缝检测方法。第一步采用Canny算法对焊缝进行边缘处理,第二步采用概率Hough变换提取焊缝中心线。实验结果表明,该方法鲁棒性强,可以精确检测出焊缝中心线,达到了期望的检测精度,解决了微细对接焊缝检测问题,结果令人满意。     

Statistical performance analysis of track initiation techniques

This paper analyzes the statistical performance of track initiation methods. It evaluates, by considering a track initiation as a problem of signal detection, the track detection probabilities and false track probabilities of four popular approaches: the rule-based method, the logic-based method, the Hough transform, and the modified Hough transform techniques. The first two methods detect the existence of tracks in a sequential fashion, and the fast two are image processing techniques that initiate tracks using a batch of frames. The analytical expressions for the track detection probability and false track probability of the four methods are derived to predict their capabilities in capturing new tracks and in rejecting false tracks due to false alarms and clutter background. Monte Carlo simulations are performed to confirm the analysis. It is observed that when the false track probability is held fixed, the logic-based and the modified Hough transform techniques have good detection performances     

基于游程元的纸印品图像的直线特征提取

针对纸印品中直线特征提取这一问题，给出游程元、中心游程元、最大领域搜索区域等定义，并在此基础上提出了一种基于游理元提取与归并的直线特征提取算法，给出了基于此算法的横格纸与方格纸中直线特征提取实验结果并对此算法的复杂性进行了分析。实验结果与算法分析表明，方法比基于Hough交换算法简单，实验效果理想，适用于文档表格等的直线特征提取。     

基于改进Hough变换和图搜索的油库目标识别

为了识别遥感图像中圆形油库目标,首先改进了基于梯度信息的圆形检测Hough变换方法,提取出图像中的圆形油库。然后根据油库的空间分布关系,提出利用深度优先的图搜索策略对检测到的圆进行分组,剔除虚警目标,最终实现油库目标区域的定位。改进的Hough变换通过利用梯度的方向信息和降低参数空间维数的方法降低了算法执行时耗费的时间和占用的存储空间,提高了圆检测的效率,同时用图搜索技术来排除虚假目标和定位目标区域,降低了虚警率,提高了识别精度。实验表明,该方法能够快速准确地识别油库目标,适用于不同分辨率的可见光遥感影像。