轮廓特征包在激光主动照明识别系统中的应用

提出了一种结合轮廓转动惯量和特征包(Bo F)算法的激光主动照明目标识别方法。介绍了转动惯量的定义,并提出了一种多尺度轮廓转动惯量特征区域检测方法和轮廓转动惯量局部不变特征提取方法。多尺度轮廓转动惯量特征区域检测方法能够提取出包含轮廓的最小特征区域,而轮廓转动惯量局部不变特征能够很好地描述轮廓的大小、位置、规则度等信息,对于各种图像变换具有不变性,并且计算效率较高。使用Bo F算法统计图像的轮廓转动惯量局部不变特征,生成归一化特征直方图作为整幅图像的特征向量,输入训练好的支持向量机分类器进行识别。实验结果表明与基于Hu矩和BP神经网络的目标识别方法相比,所提算法在旋转和仿射变换下的识别率分别提高7.33%和19.08%。     

基于区域矩的舰船图像目标特征融合方法研究

为了增强特征对图像目标的描述能力,一类重要的方法是将不同类型的特征融合。面向舰船图像目标识别,研究了基于区域矩的特征融合方法。区域矩不是计算原始图像像素的矩,而是计算图像特征的矩,具体是首先设计合适的目标特征,然后利用中心矩、Hu氏不变矩和径向矩实现特征融合,并基于KNN分类实现目标识别。仿真实验表明,与区域协方差相比,区域矩可以更好地融合舰船可见光图像或红外图像的目标特征,而且没有随机初始化问题,所以实用性和有效性更高。     

基于“轮廓-区域”多层互补特性的显著性检测

针对显著性检测在混杂场景中目标容易混淆的问题,本文借助Gestalt心理学理论,利用轮廓线索与外观线索的互补特性,提出一种基于"轮廓-区域"多层互补特性的显著性检测方法.首先,在图像超像素分割基础上,分别提取基于颜色直方图的全局外观线索和基于区域近邻关系的局部对比度线索,充分描述了区域内容的显著性特征;其次,针对混杂场景的区域外观差异小而引起的目标混淆问题,提取基于边缘的目标轮廓封闭性,描述区域轮廓的显著性特征;最后,为了提高对目标尺寸的自适应能力,本文方法使用支持向量机优化多尺度模型中的"轮廓-区域"互补特性融合过程.在ASD,MSRA10K,SED2公认数据集上的实验表明,本文基于轮廓封闭特性的显著性特性,能够有效改善目标显著性查全率、查准率,优于现有的其他先进方法.     

基于图像不变特征的目标识别新方法

基于飞机目标分析了NM(I归一化转动惯量)、不变矩、轮廓矩三种图像特征的不变性,提出了目标NMI特征提取的新方法。实验表明,基于新方法提取的NMI特征与传统的NMI特征、不变矩提取算法相比,具有良好的平移、旋转、比例不变性,且提取方法简单,易于实现。     

基于主动轮廓模型联合Camshift算法的目标跟踪方法

针对城市道路交通环境中传统Camshift算法跟踪窗不能描述运动目标轮廓以及易受近似颜色干扰跟踪丢失的问题,提出基于Snake主动轮廓模型联合Chamshift区域模型的目标跟踪方法,算法将原Camshift算法中使用的HSV颜色特征和LTP纹理特征融合,增加了抗干扰能力,同时利用多尺度小波改进的Snake主动轮廓模型进一步对物体轮廓检测,去除阴影区域,更为直观的描述了物体的轮廓。实验证明,新方法在城市道路交通监控中有良好的应用前景。     

基于局部小波矩的易混淆三维目标识别

使用多视点特性视图方法进行易混淆三维目标识别时,由于目标具有相似的轮廓,必须辅以局部特征提取以提高识别率.传统的小渡矩仅具有径向区间上的局部性,不具有角度区间上的局部性,因此提取的特征不能较好地分辨易混淆目标.利用信息采样方法,首先获得目标视图的先验信息,将目标视图分为若干个区域,由贝叶斯后验估计,分别计算基于这些区域的后验信息,然后比较其与先验信息的差异,即可获得视图中最具有分辨力的局部区域,计算这个区域上的小波矩,即可获得具有一定角度区间上的局部小波矩.研究表明,与传统的局部特征提取方法相比,这种新算法提取的局部特征具有更好的局部性,可以有效地应用于易混淆三维目标识别.     

Zernike矩不变性分析及其改进

在分析了Zernike矩不变性后,提出了一种基于图像整个区域形状描述算子的改进Zernike矩。改进的Zernike矩不仅具有旋转不变性,而且还具有改进前不具有的比例不变性。试验结果证明,和改进前的Zernike矩相比,改进后的Zernike矩具有更好的不变特征,可用作基于区域的形状描述算子。     

基于轮廓分层描述的目标识别算法研究

有效的目标轮廓分段是描述目标局部特征的关键环节.针对现有轮廓描述算法存在轮廓分段不合理的问题,本文基于认知心理学,提出了分层描述的轮廓描述算法.算法思想是首先根据角点特征将整个轮廓划分成一些轮廓分段,接着对轮廓分段的分布特点提出价值尺度,然后将多级轮廓分段按照价值尺度原则合并得到有限个能够完整描述目标轮廓的特征分段,最后将特征分段综合考虑长度尺度应用到Shape Context相似度检测模型中进行目标识别.通过对MPEG-7图像数据库中的图像进行实验分析表明该算法能够完整描述目标图像的形状特征,提高了目标识别率和形状检索率,并对部分遮挡的目标也具有良好的鲁棒性.基本满足目标识别识别和形状检索对准确率、稳定性、抗遮挡能力等方面的要求.     

基于边缘轮廓的特征匹配跟踪

介绍了目标轮廓LCS描述,并对其进行改进,建立了基于目标轮廓的特征匹配跟踪方 法。     

融合轮廓矩和Fourier描述子特征的压印字符识别

提出了一种基于混合轮廓特征的压印字符识别新方法.首先提取字符轮廓的矩不变量和Fourier描述子,然后将2种特征融合构成混合特征,最后将新特征输入BP网络进行识别.实验证明,混合轮廓特征不仅克服了2种特征单独使用时的缺点,提高了识别率,而且可以提高特征的平移、缩放以及旋转不变性.     

基于机器视觉的工件定位和识别

根据机器视觉系统具有非接触性、实时性、稳定性及高精度的特点。文中采用机器视觉技术对工件的定位和识别进行了研究。通过求取工件轮廓中心矩和轮廓轴线二阶导数的最小值,求得工件的中心坐标和旋转角度;通过提取模板工件的Hu不变矩与工件轮廓的Hu不变矩,利用轮廓的相似度量函数识别工件类型。实验结果表明,通过提取工件轮廓矩能在旋转的情况下精确地定位和识别工件。     

物理逆问题中的一个定理

本文将物象重建归结为描述这一物理过程的积分方程的定义域的反演问题。本文提出了一个定理,当被积函数满足某些先决条件时,则该定义域的轮廓可以借助于这个定理反演获得。计算机模拟结果表明了本文的论述和定理的正确性。     

融合图像轮廓矩和傅立叶描叙子的手势识别

针对手势识别中人手是复杂变形体,手部特征描叙容易受到环境因素影响的特点,提出了一种基于混合轮廓特征的手势识别的新方法.首先根据手的颜色信息将手从复杂的背景中分离出来,然后提取出手轮廓的矩不变量和Fourier描叙子特征,然后将2种特征融合构成混合特征,最后将新特征输入BP神经网络进行识别.实验表明:此方法具有较好的鲁棒性和较高的识别率.     

Reconstructing the cross sections of coronary arteries from biplane angiograms

An algorithm that reconstructs the cross sections of the lumens of coronary arteries from two mutually orthogonal X-ray projections is described. The algorithm accommodates the possibility of elliptical, crescent, or star shapes. It represents each biplane projection of a transverse slice of the arterial lumen as a binary-valued image. The single-coordinate moments of these two projection images are equal to those of the slice. Since the cross-coordinate moments of the slice are not available from the projections, an algorithm to estimate these moments based on assumptions of smoothness and connectivity is developed. Once all the missing moments are estimated, the image of the slice can be estimated by inverting these moments, using the uniqueness theorem governing the relation between an image and its moments. Preliminary tests of the algorithm on synthetic data, on hardware phantoms and on a segment of a barium-enhanced in vitro coronary artery are reported.     

Unusual boundary conditions at an interface [EM theory]

The derivation of electromagnetic boundary conditions at an interface by applying Gauss' divergence theorem to a flat pillbox or Stokes' curl theorem to a narrow contour is considered for two types of unusual boundary condition. One is an electric field discontinuity and the other is a double layer of current. It is suggested that the usual continuity proofs, based on pillboxes and contours of vanishing dimension, must be handled with care. Specifically, a `δ function' behavior of certain components along the normal is possible     

A contour-based approach to multisensor image registration

Image registration is concerned with the establishment of correspondence between images of the same scene. One challenging problem in this area is the registration of multispectral/multisensor images. In general, such images have different gray level characteristics, and simple techniques such as those based on area correlations cannot be applied directly. On the other hand, contours representing region boundaries are preserved in most cases. The authors present two contour-based methods which use region boundaries and other strong edges as matching primitives. The first contour matching algorithm is based on the chain-code correlation and other shape similarity criteria such as invariant moments. Closed contours and the salient segments along the open contours are matched separately. This method works well for image pairs in which the contour information is well preserved, such as the optical images from Landsat and Spot satellites. For the registration of the optical images with synthetic aperture radar (SAR) images, the authors propose an elastic contour matching scheme based on the active contour model. Using the contours from the optical image as the initial condition, accurate contour locations in the SAR image are obtained by applying the active contour model. Both contour matching methods are automatic and computationally quite efficient. Experimental results with various kinds of image data have verified the robustness of the algorithms, which have outperformed manual registration in terms of root mean square error at the control points.     

基于多特征融合与支持向量机的手势识别

针对手势识别中人的手部特征描述易受到环境因素影响,手势识别率低等问题,并考虑到单个特征的局限性,提出了一种基于Hu矩和HOG特征融合的支持向量机手势识别新方法。该方法首先对处理后的手势图像提取局部的HOG特征,然后针对手势的轮廓提取全局Hu矩特征,再将两种特征融合成混合特征,并通过主成分分析法对混合特征进行降维形成最终分类特征,并将新特征输入到支持向量机中进行识别。实验表明,该方法具有较好的鲁棒性和较高的识别率。     

具有任意斜缝的微带缝隙天线研究

本文利用谱域方法和互易定理,建立了具有任意斜缝的微带缝隙天线的一般化求解方程,并用矩量法求其数值解。文中给出了天线输入阻抗随缝隙倾斜角变化的数值结果,最后给出了3GHz频段的设计曲线。     

任意形状导体目标的极点求解

从理论上求解极点,频域矩量法结合围线积分是通用且准确的方法,但由于计算量大而一直用于处理旋转对称目标的求解.本文提出Chebyshev多项式展开格林函数的方法,把频率因子从电场积分方程中分离出来,实现了多频点矩量法的快速计算,解决了任意形状导体目标极点的求解问题.最后对围线积分方法进行适当改进,并求解了三种目标的极点.     

Zernike moment and local distribution fitting fuzzy energy-based active contours for image segmentation

This paper presents a new region-based active contour model for extracting the object boundaries in an image, based on techniques of curve evolution. The proposed model introduces an energy functional that involves intensity distributions in local image regions and fuzzy membership functions. The local image intensity distribution information used to guide the motion of the contour, in the paper, is derived by Hueckel operator in the neighborhood of each image point. The parameters of Hueckel operator are estimated by a set of orthogonal Zernike moments before curve evolution. Meanwhile, the fuzzy membership functions are used to measure the association degree of each image pixel to the region outside and inside the contour. To minimize the energy functional, instead of solving the Euler–Lagrange equation of the underlying problem, the paper employs a direct method to compute the energy alterations. As a result, the model can deal with images with intensity inhomogeneity. In addition, the model effectively alleviates the sensitivity to contour initialization. Moreover, the model reduces computational cost, avoids problems associated with choosing time steps as well as allows fast convergence to the segmentation solutions. Experimental results on synthetic, real images and comparisons with other models show the desired performances of the proposed model.