Measure of microscopy mineral image clarity constructed using the sequentially combined toggle and top‐hat based contrast operator

Correctly and effectively quantifying the clarity of microscopy mineral image is important and useful to produce clear image for mineral analysis. To well quantify the clarity of mineral image, an effective measure constructed using the sequentially combined toggle and top‐hat based contrast operator is proposed in this article. First, the sequentially combined toggle and top‐hat based contrast operator is used to extract the effective features which represent the clarity of mineral image. Second, the multiscale clarity features corresponding to each scale are extracted. Finally, after combining the multiscale clarity features in one feature image, the mean value of the feature image is constructed as the measure of mineral image clarity. Because the sequentially combined toggle and top‐hat based contrast operator could effectively extract the clarity features, the clarity features are directly used as the measure of image clarity. Therefore, the proposed measure is effective and reasonable. The experimental results on different types of microscopy mineral images verified the effective performance of the proposed measure. Microsc. Res. Tech. 76:811–817, 2013. © 2013 Wiley Periodicals, Inc.     

Morphological enhancement of microscopy mineral image using opening‐ and closing‐based toggle operator

To enhance unclear microscopy mineral images, an algorithm based on toggle operator using opening and closing is proposed in this paper. Firstly, the specified toggle operator using opening and closing through designing the selection rules is analysed. Secondly, after importing the multiscale theory into the specified toggle operator, useful mineral image features, especially the mineral details, are extracted using the multiscale theory‐based toggle operator. Finally, the mineral image is enhanced through the strategy of enlarging the contrast between the extracted bright and dark image features. Experimental results on different types of mineral images verified that the proposed algorithm could effectively enhance mineral images and performed better than some other algorithms. The enhanced mineral image is clear and contains rich mineral details, whereas the grey scale distribution of the original mineral image is appropriately maintained. This would be useful for the further mineral analysis. Therefore, the proposed algorithm could be widely used for image‐based mineral applications.     

Evaluation of scanning electron microscopy images of a model dressing using image feature extraction techniques and principal component analysis

Twelve dressing systems made by varying protein type, oil level, CaCl₂, NaCl, and sucrose, were examined using scanning electron microscopy. Images from the 12 systems were quantitatively analysed using methods of feature extraction. These methods were based on vectorisations of the images followed by principal component analysis on the extracted vectors. These techniques were used to examine the reproducibility of the acquired images as well as to relate the images to rheologic and sensory texture parameters. Two feature extraction methods were used: the angle measure technique (AMT) and the absolute difference method (ABDF). The ABDF method used fewer principal components to extract information from images relevant to the complex modulus/sensory viscosity of the system, but the information seemed equally well preserved by the two-feature extraction methods. The AMT was more efficient in classifying the images with respect to protein type. A fair correlation between images and complex modulus was obtained (R=0.73). It is suggested that a better correlation might be obtained by adding more systems, increasing the number of areas imaged for each system as well as avoiding systems of low viscosity.     

Compensation of inhomogeneous fluorescence signal distribution in 2D images acquired by confocal microscopy

In images acquired by confocal laser scanning microscopy (CLSM), regions corresponding to the same concentration of fluorophores in the specimen should be mapped to the same grayscale levels. However, in practice, due to multiple distortion effects, CLSM images of even homogeneous specimen regions suffer from irregular brightness variations, e.g., darkening of image edges and lightening of the center. The effects are yet more pronounced in images of real biological specimens. A spatially varying grayscale map complicates image postprocessing, e.g., in alignment of overlapping regions of two images and in 3D reconstructions, since measures of similarity usually assume a spatially independent grayscale map. We present a fast correction method based on estimating a spatially variable illumination gain, and multiplying acquired CLSM images by the inverse of the estimated gain. The method does not require any special calibration of reference images since the gain estimate is extracted from the CLSM image being corrected itself. The proposed approach exploits two types of morphological filters: the median filter and the upper Lipschitz cover. The presented correction method, tested on images of both artificial (homogeneous fluorescent layer) and real biological specimens, namely sections of a rat embryo and a rat brain, proved to be very fast and yielded a significant visual improvement. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

基于字符特征约束的自适应车牌校正提取

针对复杂多变环境中难以快速、精确提取车牌的问题,提出了一种利用字符特征智能校正提取车牌的方法。首先通过Gamma校正和Canny算子结合的方法在灰度图中实现自适应阈值边缘检测,解决了分割阈值选取的难题;然后应用字符特征约束条件提取特征轮廓,根据特征轮廓分布规律提取车牌候选区,避免复杂运算的同时提高了定位准确性;最后对候选区进行线性畸变校正并利用行灰度跳变统计实现了车牌真实性验证和精确提取,为后续的识别工作提供了良好条件。对不同环境中随机采集的700幅高清图像进行测试,综合提取准确率为96%,提取车牌字符规整、无多余残留信息。实验结果显示,该方法对图像中车牌状态、背景环境、光照条件等限制极少,具有更广的适用范围和更强的鲁棒性。     

基于冗余提升形态小波的非对称表面特征提取研究

针对提升小波提取非对称表面形貌特征时存在平移变动性和较差的方向选择性,将具有平移不变性和良好的方向选择性的冗余提升形态Haar小波应用到非对称表面的特征提取中。开展了该形态小波对具有显著特征的非对称平顶珩磨的缸套内表面进行特征提取的分析;同时结合仿真的方法,研究了该形态Haar小波对一个模拟的具有一定长度沟槽特征的空间表面进行特征提取的效果。研究结果表明,冗余提升形态Haar小波对非对称表面形貌进行形态特征提取时,在各尺度重构的信号沿特征边缘几乎没有变动且无畸变,可实现准确提取。     

昆虫翅膀运动变形测量中的图像特征提取

通过分析翅脉图像的特点, 提出了一种用于提取昆虫图像翅脉和翅脉交点的亚像素级图像处理方法。该方法应用小波理论对图像消噪,并采用中值滤波预处理图像,然后利用小波同态滤波和双线性广义模糊相结合的算法增强图像的翅脉信号。应用基于Hession矩阵的亚像素提取算法提取翅脉中心点的位置,并根据翅脉方向变化的连续性,利用邻域角度约束方法确定翅脉交叉点。最后,给出几种算法实验结果的比较和分析,结果表明,该方法成功实现了翅脉和翅脉交点特征的提取,并有效抑制了噪声和干扰。     

基于区域化形态滤波的分合闸线圈电流信号特征值提取方法研究

针对断路器分合闸线圈电流信号特征值提取效率不能满足在线监测系统要求的问题,对断路器在线圈尺寸偏小、弹簧力矩偏小、线圈电阻偏大和控制电压偏低等4种故障下线圈电流信号的特点进行了归纳,说明了线圈电流信号区域化的可行性,对数学形态学的基本运算、结构元素及具备抗干扰能力的区间搜索求极值方法进行了研究,提出了一种数学形态滤波结合区间搜索求极值的特征值提取方法。利用ZF7A-12断路器实验平台分别进行了正常状态及4种故障状态实验以获取实验数据,并在Matlab中把该方法与传统小波结合求导方法进行了仿真对比。仿真结果表明:在5种状态下,该方法均能准确而高效地提取特征值,它与传统方法的特征值提取误差分别为4%和5%,同时其算法耗时仅为传统方法的25%。     

基于循环提取有效信息的主轴承故障特征增强方法

针对航空发动机主轴承发生故障时特征信息提取不充分的问题,提出一种基于循环提取有效信息的主轴承故障特征增 强方法。 该方法首先对原始振动信号进行小波包分解,计算得到各个节点分量的相关系数值和峭度值,将其进行归一化融合为 一个综合参数 Pi;其次根据特征信息循环提取准则定义一个置信区间,该区间将所有节点分量划分为高信噪比信号、低信噪比 信号和高噪信号 3 个部分;然后不断筛选出高信噪比信号直至达到终止条件;最后重构所有高信噪比信号,并进行包络解调提 取出轴承微弱故障特征。 经仿真信号验证,去噪信号的信噪比相对于去噪前提升了 11. 31 dB。 基于航空发动机中介轴承模拟 试验台所测数据开展了特征信息循环提取方法有效性的综合验证,并对某型航空发动机主轴承振动信号进行了分析。 实践表 明:该方法适用于强背景噪声干扰工况下滚动轴承的特征提取,能准确诊断航空发动机主轴承故障。     

非编码标志点的几何形心提取的研究

在反求工程中,利用毛学测量得到的点云数据只能得到某个视角内的物体,为了得到完整的点云实体,需要对不同视角的点云数据进行拼合。在现有算法中,绝大多数算法都是基于曲面拓扑特征这一前提进行拼合的,这就使得那些曲面平滑,表面拓扑信息不明显的点曲面拼合很难得到较好的效果。之后对于特征不明显的曲面进行拼合,提出了一些基于添加外部特征的方法,标志球,带编码的标志点等。可是这些方法也存在着计算量大的缺陷。基于以上的现状,本文提出了一种基于非编码标志点的曲面拼合方法。直接从图僚中提取标志点的几何形心作为曲面局部匹配的对应关系,具有计算简单,精确度高的特点。     

Compression of fluorescence microscopy images based on the signal-to-noise estimation

Modern microscopic techniques like high-content screening (HCS), high-throughput screening, 4D imaging, and multispectral imaging may involve collection of thousands of images per experiment. Efficient image-compression techniques are indispensable to manage these vast amounts of data. This goal is frequently achieved using lossy compression algorithms such as JPEG and JPEG2000. However, these algorithms are optimized to preserve visual quality but not necessarily the integrity of the scientific data, which are often analyzed in an automated manner. Here, we propose three observer-independent compression algorithms, designed to preserve information contained in the images. These algorithms were constructed using signal-to-noise ratio (SNR) computed from a single image as a quality measure to establish which image components may be discarded. The compression efficiency was measured as a function of image brightness and SNR. The alterations introduced by compression in biological images were estimated using brightness histograms (earth's mover distance (EMD) algorithm) and textures (Haralick parameters). Furthermore, a microscope test pattern was used to assess the effect of compression on the effective resolution of microscope images.     

Incipient fault feature extraction of rolling bearings based on the MVMD and Teager energy operator

Aiming at the problems that the incipient fault of rolling bearings is difficult to recognize and the number of intrinsic mode functions (IMFs) decomposed by variational mode decomposition (VMD) must be set in advance and can not be adaptively selected, taking full advantages of the adaptive segmentation of scale spectrum and Teager energy operator (TEO) demodulation, a new method for early fault feature extraction of rolling bearings based on the modified VMD and Teager energy operator (MVMD-TEO) is proposed. Firstly, the vibration signal of rolling bearings is analyzed by adaptive scale space spectrum segmentation to obtain the spectrum segmentation support boundary, and then the number K of IMFs decomposed by VMD is adaptively determined. Secondly, the original vibration signal is adaptively decomposed into K IMFs, and the effective IMF components are extracted based on the correlation coefficient criterion. Finally, the Teager energy spectrum of the reconstructed signal of the effective IMF components is calculated by the TEO, and then the early fault features of rolling bearings are extracted to realize the fault identification and location. Comparative experiments of the proposed method and the existing fault feature extraction method based on Local Mean Decomposition and Teager energy operator (LMD-TEO) have been implemented using experimental data-sets and a measured data-set. The results of comparative experiments in three application cases show that the presented method can achieve a fairly or slightly better performance than LMD-TEO method, and the validity and feasibility of the proposed method are proved.     

基于特征提取的三维标注技术

对三维模型表达产品信息的方式和三维标注技术进行了研究,提出了基于特征提取的三维标注方法,定义了三维的精度特征符号.基于Pro/E平台,建立了三维精度特征符号库,并将三维精度特征符号和三维模型定义在同一组数据中.实现了3D模型上产品设计信息的三维标注,其中三维标注信息能被提取并保存在数据库中,用于后续的加工制作.     

Palyno‐morphological investigations of subtropical endangered flora of Capparidaceae through light and scanning electron microscopy

The research was performed to investigate pollen morphology of endangered species of Capparidaceae in subtropical regions of Pakistan. The distinguishing characters were investigated by using light microscope and scanning electron microscope. Palynological study is comprised of pollen shape, pollen type, exine sculpturing, polar and equatorial diameter, length and width of colpi, mesocolpium, and exine thickness. In polar view, Cleome viscosa exhibited the highest pollen size 26.4 (32.7–24.5 μm) ±0.776 whereas Capparis spinosa appeared to be the lowest 12.6 (14.5?10.7 μm) ±0.400. In equatorial view, Cleome viscosa had the largest pollen size 17.1 (20.0–15.0 μm) ±0.606 and Capparis spinosa had the smallest pollen size 9.7 (12.50–8.00 μm) ±0.394. The maximum fertility percentage has been observed in Capparis spinosa, that is, 98.96% and minimum in Cleome viscosa, that is, 82.93%. Diagnostic key has been constructed to state the essential diagnostic features by means of which the taxa can be identified. Remarkable variations have been observed in pollen size, shape, and exine sculpturing. All the selected species were tricolporate. Prolate to subprolate pollen were observed. There is a great variation existed in exine sculpturing such as in Capparis decidua and C. sp. nova sculpturing is reticulate, in Capparis himalayensis sculpturing is Scabrate granulate, in Capparis spinosa sculpturing is Psilate, in Cleome viscosa sculpturing is regulate‐reticulate, in Dipterygium glaucum sculpturing is regulate and in Gynandropsis gynandra sculpturing is striate‐regulate. On the basis of overall characteristics of pollen it seems that palynology of this family is helpful at the generic and specific level.     

基于Wedgelet的CT体数据线特征提取

线特征是描述CT体数据的重要特征之一,是基于工业CT逆向设计的重要基础。该文通过分析单尺度下Wedgelet的组成及相互间的联系,得到一种快速Wedgelet分解方法。以此为基础,考虑到CT体数据中的大部分线特征并不是以独立的形式存在,而是以不同灰度区域相连形式存在的客观事实,提出一种基于Wedgelet的CT体数据线特征提取方法。首先将体数据按3个相互垂直的方向进行切片划分;然后对每组切片序列图像进行基于多尺度Wedgelet分解的线特征提取;最后对3个方向的线特征进行融合,从而得到CT体数据的线特征。实际数据的数字实验结果表明,该方法能有效地提取出CT体数据中的线特征。     

基于序列图像提取稳定特征点的虹膜识别算法

为了尽可能降低不稳定特征点对识别率的影响,研究提出了基于序列图像提取稳定特征点的虹膜识别算法.该算法首先用二维Gabor滤波器对序列虹膜图像提取特征编码,然后对该序列特征编码求交集以提取稳定特征点,并利用这些稳定特征点建立虹膜的特征模板库,最后通过计算相似度,获得识别结果.在实验室采集的序列虹膜图库上,当等错率为0.3017%,分类阈值为0.6402时,正确识别率可以达到99.73%.实验证明该算法是有效、可行的,并更好地提高了虹膜的分类精度和改善了虹膜的识别性能.     

基于各向异性数学形态学的火焰图像边缘检测

为了更加有效地提取锅炉燃烧火焰图像的边缘,提出了一种基于各向异性数学形态学的火焰图像边缘检测方法.首先计算火焰图像的平均平方梯度向量并由其表示平均梯度向量,然后对平均梯度向量进行扩散得到图像的平均梯度向量场,并计算图像各像素点的平均梯度方向,最后根据各点的方向信息构造适合的形态结构元素,并计算其形态学梯度,据此检测出火焰图像的边缘.针对大量火焰图像进行的实验结果表明,与现有的边缘检测方法包括Roberts方法、Sobel方法、Prewitt方法、Canny方法、Log方法、各向同性数学形态学方法以及自适应邻域方法相比,该方法检测出的边缘,定位更加准确,边缘完整清晰,算法抗噪性更好,运算速度快.     

基于体素有向连通性的深度图像拉伸特征提取

针对深度图像中的拉伸特征,提出一种基于体素连通性和区域生长的提取方法。通过线性八叉树结构建立深度图像数据的体素模型,并改进了体素邻域的搜索算法;利用种子体素特定方向上的连通性进行区域生长;然后对生长点进行判断并提取出拉伸特征数据。文中将该方法应用在液舱深度数据上,并对提取结果进行了讨论。     

CT影像中一种基于知识的脊髓自动提取方法

基于CT影像人体结构的特征知识,提出了用3个主要步骤实现脊髓的自动提取功能.并在检测脊髓概率区关键步骤中,基于脊髓及其周围结构的特征知识,建立了一个全新的特征模型进行脊髓内一点的检测,并基于该点进行区域增长得到脊髓概率区,进而在脊髓概率区内实现脊髓的检测.在临床60例患者CT图像序列的试验中,躯干轮廓检测率全部达到100％,脊髓概率区的检测率有2例为99％,其余均为100％,基于脊髓概率区的脊髓检测率全部可以达到100％.引入特征模型自适应修正,可以实现全部60例患者CT图像序列脊髓的自动提取.运行于笔记本平台上,患者CT图像序列脊髓检测时间可以达到3 s左右,完全满足临床要求.脊髓自动提取功能的实现,避免了临床放疗医师进行手动勾画的烦琐工作,同时也降低了勾画结果对放疗医师技术水平的依赖,在临床放射治疗领域具有重要意义.     

Out‐of‐focus background subtraction for fast structured illumination super‐resolution microscopy of optically thick samples

We propose a structured illumination microscopy method to combine super resolution and optical sectioning in three‐dimensional (3D) samples that allows the use of two‐dimensional (2D) data processing. Indeed, obtaining super‐resolution images of thick samples is a difficult task if low spatial frequencies are present in the in‐focus section of the sample, as these frequencies have to be distinguished from the out‐of‐focus background. A rigorous treatment would require a 3D reconstruction of the whole sample using a 3D point spread function and a 3D stack of structured illumination data. The number of raw images required, 15 per optical section in this case, limits the rate at which high‐resolution images can be obtained. We show that by a succession of two different treatments of structured illumination data we can estimate the contrast of the illumination pattern and remove the out‐of‐focus content from the raw images. After this cleaning step, we can obtain super‐resolution images of optical sections in thick samples using a two‐beam harmonic illumination pattern and a limited number of raw images. This two‐step processing makes it possible to obtain super resolved optical sections in thick samples as fast as if the sample was two‐dimensional.