噪声符合高斯分布的曲面图像分割

针对噪声符合高斯分布的曲面图像分割问题,提出了一种基于变分水平集方法的隐式曲面上噪声符合高斯分布的图像分割模型。为定义隐式曲面上图像区域划分的动态轮廓线,引入另一个动态水平集函数,其零水平集与隐式曲面的交线即为曲面上区域划分的轮廓线。该模型采用N个水平集函数划分2^N个区域的区域竞争策略。通过变分方法得到图像分割空间轮廓线演化的梯度降方程。通过显式差分格式对演化方程进行离散。实验结果表明,该模型对曲面上噪声符合高斯分布的图像具有良好的分割效果,并且在图像分割的同时能够完全保持曲面固有的几何特征。     

ICA based speckle filtering for target extraction in SAR images using adaptive space separation

A novel approach based on independent component analysis (ICA) for speckle filtering and target extraction of synthetic aperture radar (SAR) images is proposed using adaptive space separation with weighted information entropy (WIE) incorporated. First the basis and the independent components are respectively obtained by ICA technique, and WIE of the image is computed; then based on the threshold computed from function T-WIE (threshold versus weighted-information-entropy), independent components are adaptively separated and the bases are classified accordingly. Thus, the image space is separated into two subspaces: "clean" and "noise". Then, a proposed nonlinear operator ABO is applied on each component of the 'clean' subspace for further optimization. Finally, recovery image is obtained reconstructing this subspace and target is easily extracted with binarisation. Note that here T-WIE is an interpolated function based on several representative target SAR images using proposed space separation algorithm.     

基于数字图像技术的露石混凝土表面构造研究

运用数字图像技术实现了露石混凝土路面(EACCP)图像像素值量化计算,建立了露石表面像素差平均值与构造深度的关系模型;通过采集的数字图像计算分析了露石表面构造深度,评价了EACCP露石表面构造质量。实例分析表明:数字图像技术的露石表面构造检测方法,能方便快捷地进行露石路表构造深度检测,有利于实现测量工作的连续化。     

一种基于核局部保留投影的人脸识别方法

为了有效提取人脸的非线性结构信息,提出一种新的基于最大散度差的核判别局部保留投影方法.首先通过核函数将样本数据映射到高维特征空间,计算特征空间中样本的散度矩阵,其次将样本原始空间中的近邻图嵌入到散度矩阵,最后采用最大散度差准则进行特征提取.在PIE与Yale人脸数据库上的实验结果表明,提出的人脸识别方法最高识别率可达到99%.      

基于结构光的多投影显示系统图像对准算法

为了解决多投影显示系统的图像对准问题,提出了一种基于结构光投影技术的对准算法.该算法通过求取等相位线的交点来建立投影机图像与相机拍摄图像间的映射关系,对于投影机图像上任一像素点,有水平和垂直2个相位值.在相机图像的水平相位展开图中找出与该点水平相位值相等的离散坐标点的位置,拟合出一条水平等相位线,同理,可以得到它的一条垂直等相位线;求出水平和垂直等相位线的交点,即为该点对应于相机图像中的像素点.该算法无需知道显示墙的解析表达式和相机的内部参数,适用于任意光滑的曲面显示墙.对准后图像与原始图像的对比实验表明:峰值信噪比达到27.904,结构相似度为0.972 4,说明该算法能有效提高图像的对准精度.      

基于贝叶斯决策的航空影像自动配准

为消除像点投影差对航空影像目标监测中影像配准的影响,提出了一种基于贝叶斯决策理论的像点投影差消除方法.该方法通过推导分析像点投影差的分布规律及其对影像配准的影响,设置训练样本区,提取大量特征匹配对,计算得到投影差分布参数,并基于贝叶斯决策理论构建了像点投影差消除准则.为验证其有效性,选用KIT AIS影像数据进行了实验,比较分析了投影差消除前后的配准影像结果.分析结果显示,消除后差分视觉效果得到改善,信息熵减小10%,表明本文方法可有效提高航空影像配准的精度.      

Analysis of the pencil of conics with double complex contact and its application to camera calibration

In this paper,we introduce a novel class of coplanar conies,the pencil of which can doubly contact to calibrate camera and estimate pose.We first analyze the properties of con-axes and con-eccentricity ellipses, which consist of a natural extending pattern of concentric circles.Then the general case that two ellipses have two repeated complex intersection points is presented.This degenerate configuration results in a one-parameter family of homographies which map the planar pattern to its image.Although it is unable to compute the complete homography,an indirect 3-degree polynomial or 5-degree polynomial constraint on intrinsic parameters from one image can also be used for camera calibration and pose estimation under the minimal conditions.Furthermore, this nonlinear problem can be treated as a polynomial optimization problem(POP) and the global optimization solution can be also obtained by using SparsePOP(a sparse semidefinite programming relaxation of POPs). Finally,the experiments with simulated data and real images are shown to verify the correctness and robustness of the proposed technique.     

IMAGE ANALYSIS BASED ON EDGE DETECTION TECHNIQUES

IntroductionEdges are pixels where brightness changesabruptly and often used in image analysis for find-ing region boundaries.It locates sharp changes inthe intensity function.Edges detection is basic im-age features.They carry useful information aboutobject boundaries.Edges can be used for object i-dentification,image analysis and image filteringapplications as well.We shall consider as an edgethe border between two homogeneous image re-gions having different illumination.This definitionimp…     

海量影像数据的快速浏览设计

信息技术和传感器技术的飞速发展,使得遥感图像的数据量呈几何级数的递增.当浏览图像或缩放时传统的方法速度都比较慢,特别是缩小图像时要读取整个影像数据,而且还要间隔的抽取数据,速度之慢几乎难以忍受,当对影像数据进行数据矢量化的时候,工作效率就非常低.本文提出了一种在打开文件时花出一定时间对影像文件进行临时文件重建,做成倒金字分层结构,并通过内存映射文件读取数据,简化了文件读取操作.这样每次浏览或缩放图像时就可以无等待了.     

Modified gray level difference-based thresholding segmentation and its application in X-Ray welding image

Thresholding is a popular image segmentation method that often requires as a preliminary and indispensable stage in the computer aided image process, particularly in the analysis of X-ray welding images. In this paper, a modified gray level difference-based transition region extraction and thresholding algorithm is presented for segmentation of the images that have been corrupted by intensity inhomogeneities or noise. Classical gray level difference algorithm is improved by selective output of the result of the maximum or the minimum of the gray level with the pixels in the surrounding, and multi-structuring of neighborhood window is used to represent the essence of transition region. The proposed algorithm could robustly measure the gray level changes, and accurately extract transition region of an image. Comparisons with other approaches demonstrate the superior performance of the proposed algorithm.     

融合式空间塔式算子和HIK-SVM的交通标志识别研究

在交通标志识别问题上,提出了一种基于融合式的空间塔式算子和直方图交叉核支持向量机(HIK-SVM)的分类方法.在该方法中,通过提取图像的灰度塔式词袋直方图(Gray-PHOW)特征、颜色塔式词袋直方图(Color-PHOW)特征和塔式边缘方向梯度直方图(PHOG)特征来对交通标志的外观、颜色和轮廓信息进行描述.通过提取空间塔式直方图特征,能很好地对图像各种特征的空间分布状况进行描述.提取到图像的外观、颜色、轮廓和特征的空间分布信息后,对其进行融合,最后得到的融合式的空间塔式特征具有很强的鲁棒性.将该融合式特征送入HIK-SVM进行训练和分类,取得了极其高的识别效果.     

An Image Retrieval Method Based on Color and Texture Features

The technique of image retrieval is widely used in science experiment, military affairs, public security,advertisement, family entertainment, library and so on. The existing algorithms are mostly based on the characteristics of color, texture, shape and space relationship. This paper introduced an image retrieval algorithm, which is based on the matching of weighted EMD(Earth Mover‘s Distance) distance and texture distance. EMD distance is the distance between the histograms of two images in HSV(Hue, Saturation, Value) color space, and texture distance is the L1 distance between the texture spectra of two images. The experimental results show that the retrieval rate can be increased obviously by using the proposed algorithm.     

HIERARCHICAL CONTENT BASED IMAGE RETRIEVAL

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Mutual information optimization based dynamic log-polar image registration

Log-polar transformation(LPT)is widely used in image registration due to its scale and rotation invariant properties.Through LPT,rotation and scale transformation can be made into translation displacement in log-polar coordinates,and phase correlation technique can be used to get the displacement.In LPT based image registration,constant samples in digitalization processing produce less precise and effective results.Thus,dynamic log-polar transformation(DLPT)is used in this paper.DLPT is a method that generates several sample sets in axes to produce several results and only the effective results are used to get the final results by using statistical approach.Therefore,DLPT can get more precise and effective transformation results than the conventional LPT.Mutual information(MI)is a similarity measure to align two images and has been used in image registration for a long time.An optimal transform for image registration can be obtained by maximizing MI between the two images.Image registration based on MI is robust in noisy,occlusion and illumination changing circumstance.In this paper,we study image registration using MI and DLPT.Experiments with digitalizing images and with real image datasets are performed,and the experimental results show that the combination of MI with DLPT is an effective and precise method for image registration.     

基于二维耦合映像格子模型的图像加密

为了平衡混沌系统的复杂性和效率之间的关系，将分段Logistic映射（piecewise Logistic map，PLM）引入到二维耦合映像格子（2D coupled map lattices，2DCML）模型中. 采用暂态转换以使模型的输出序列服从均匀分布，进而得到T2DCML模型，基于此模型提出了一类图像加密算法. 在加密算法中，利用模型输出的伪随机序列构造两个初等变换矩阵，对图像进行置乱操作；然后再从模型中提取状态值的比特构造整数序列，对置乱后的图像进行扩散操作；经过若干轮的置乱与扩散操作，产生最后的加密图像. 仿真实验及性能分析表明:该算法的相关系数的绝对平均值为0.001 3，信息熵为7.999 3，像素变化率（number of pixel change rate，NPCR）和统一平均变化强度（unified average change intensity，UACI）分别为99.63%和33.60%，能够有效满足图像在网络中安全传输的需求.      

A Target-Orientated Marker Image Binarization Method for Orthopaedic Surgical Navigation System

Camera calibration is the key technique in a C-arm based orthopaedic surgical navigation system. The extraction of marker location information is a necessary step in the calibration process. Ideal marker images should possess uniform background and contain marker shadow only, but in fact marker images always possess nonuniform background and are contaminated by noise and unwanted anatomic information, making the extraction very difficult. A target-orientated marker shadow extraction method was proposed. With this method a proper threshold for marker image binarization can be determined.     

Detecting shifted double JPEG compression tampering utilizing both intra-block and inter-block correlations

Copy-paste forgery is a very common type of forgery in JPEG images.The tampered patch has always suffered from JPEG compression twice with inconsistent block segmentation.This phenomenon in JPEG image forgeries is called the shifted double JPEG(SDJPEG) compression.Detection of SDJPEG compressed image patches can make crucial contribution to detect and locate the tampered region.However,the existing SDJPEG compression tampering detection methods cannot achieve satisfactory results especially when the tampered region is small.In this paper,an effective SDJPEG compression tampering detection method utilizing both intra-block and inter-block correlations is proposed.Statistical artifacts are left by the SDJPEG compression among the magnitudes of JPEG quantized discrete cosine transform(DCT) coefficients.Firstly,difference 2D arrays,which describe the differences between the magnitudes of neighboring JPEG quantized DCT coefficients on the intrablock and inter-block,are used to enhance the SDJPEG compression artifacts.Then,the thresholding technique is used to deal with these difference 2D arrays for reducing computational cost.After that,co-occurrence matrix is used to model these difference 2D arrays so as to take advantage of second-order statistics.All elements of these co-occurrence matrices are served as features for SDJPEG compression tampering detection.Finally,support vector machine(SVM) classifier is employed to distinguish the SDJPEG compressed image patches from the single JPEG compressed image patches using the developed feature set.Experimental results demonstrate the efficiency of the proposed method.     

Poisson noise removal based on nonlocal total variation with Euler’s elastica pre-processing

An enhancement-based Poisson denoising method for photon-limited images is presented. The noisy image is firstly pre-processed for enhancing incomplete object information, and then it is denoised while preserving the restored structural details. A variational regularization model based on Euler’s elastica (EE) is proposed for image enhancement pre-processing. A nonlocal total variation (NLTV) regularization model is then employed in the second stage of image denoising. The above two optimization problems are solved by the alternating direction method of multipliers (ADMM). For Poissonian images with low image peak values, experiments demonstrate the validity and efficiency of the proposed method for both restoring geometric structure and removing noise.     

基于Kittler最小误差分割算法的小视场星图分割

小视场星图易受光照不均和噪声影响,常用阈值分割算法存在处理效果不佳或效率较低的不足.针对星图灰度的高斯分布特征,基于贝叶斯最小误差理论,提出利用Kittler最小误差分割算法处理小视场星图.以视频测量机器人为测量平台,以"优度法"、区域一致性、区域对比度和时间复杂度为评价指标,对比了常用的阈值分割算法和一维最大熵法,验...     

图像分块下的隧道裂缝识别方法

针对隧道衬砌表面不均匀光照、渗水和噪声等强视觉干扰,设计了基于图像分块的隧道衬砌裂缝检测算法;根据中国西部地区的地理特征和隧道衬砌的外观病害,研制开发出一种快速、自动化的非接触式智能隧道结构物外观检测系统; 以非均匀光照下隧道图像数据集为研究对象,在图像分块的基础上提出一种适用于隧道裂缝特征提取的图像识别算法;研究了电子元件产生的噪声,并分析和总结了隧道衬砌的灾害特征;根据裂缝特征和分辨率将图像矩阵划分为适当数量的区域块,根据区域块的灰度特征将原始图像划分为目标背景区、目标病害区、病害背景区和其他区域,通过最大类间方差法和局部阈值法分割得到了隧道裂缝的粗图像,在此基础上进行了粗图像裂缝特征提取;对原始图像的每个区域块进行了对比度受限的自适应直方图均衡操作和局部阈值分割,得到了细节图像;将细节图像和粗图像的重叠区域设为理想裂缝二值化图像;结合隧道结构物外观检测系统对不同方向的裂缝图像进行了二值化试验,并通过隧道裂缝定位和投影法得到了隧道衬砌图像中裂缝的位置信息和方向。研究结果表明:提出的算法对隧道裂缝识别的准确值、召回率和F值可分别达90.34%、98.78%和94.37%,既可以保证隧道裂缝的完整性,也可以在非均匀光照下最大程度地保留目标裂缝的细节,可用于处理一般灰度图像的二值化问题。