Digital image processing for nonperiodic objects and an on-line image processing system for high resolution electron microscopy

A digital image processing method for noise removal and image enhancement in nonperiodic structural images is described. The method for noise removal uses a reversible transform between an image and image autocorrelation function. The Laplacian filter is then employed for image enhancement. Furthermore, an on-line image processing system for highresolution TEM is presented.     

Crystal structure retrieval by maximum entropy analysis of atomic resolution incoherent images

In this paper, we discuss the application of the maximum entropy method to atomic resolution Z -contrast images acquired in a scanning transmission electron microscope. Z -contrast is an incoherent imaging technique, and can be described as a convolution between an object function (the real-space map of the columnar scattering cross-section to high angles) and a point spread function (the effective electron probe). As such, we show that the technique is ideally suited to maximum entropy analysis which can, given an electron probe distribution, retrieve the 'most likely' Z -contrast object function. Using both simulated and experimentally acquired data, we explore the capabilities of maximum entropy analysis when applied to atomic resolution Z -contrast images, drawing conclusions on both the range of applicability of the technique and the nature of the retrieved crystal structures. Ultimately, we show the way in which the combination of Z -contrast imaging with maximum entropy analysis can be used to yield important information on unexpected atomic structures.     

A method using an on-line digital computer for the improvement of resolution of backscattered electron images

In principle, the resolution of backscattered electron (BSE) images can be little improved, even though an infinitely small beam size is achieved by various improvements in the intrinsic instrument. In order to circumvent this problem, a method is proposed which utilizes an on-line digital computer for the image recording and processing. The major image-processing tools are reduction, expansion, super-imposition with matching of the images, and high-emphasis filtering in the Fourier domain. By using various combinations of these techniques, the resolution of BSE images has been significantly improved. The validity of these improved images has been confirmed. In the case of a BSE image with too wide a dynamic range, both the present method and digital homomorphic filtering provide successful results.     

Column ratio mapping: a processing technique for atomic resolution high-angle annular dark-field (HAADF) images

An image processing technique is presented for atomic resolution high-angle annular dark-field (HAADF) images that have been acquired using scanning transmission electron microscopy (STEM). This technique is termed column ratio mapping and involves the automated process of measuring atomic column intensity ratios in high-resolution HAADF images. This technique was developed to provide a fuller analysis of HAADF images than the usual method of drawing single intensity line profiles across a few areas of interest. For instance, column ratio mapping reveals the compositional distribution across the whole HAADF image and allows a statistical analysis and an estimation of errors. This has proven to be a very valuable technique as it can provide a more detailed assessment of the sharpness of interfacial structures from HAADF images. The technique of column ratio mapping is described in terms of a [110]-oriented zinc-blende structured AlAs/GaAs superlattice using the 1 angstroms-scale resolution capability of the aberration-corrected SuperSTEM 1 instrument.     

在线分析样气的原位处理法研究

为了克服传统直接抽取法样气处理系统的缺点和局限性,原位安装法（即直插式）是项值得肯定的技术进步。但是工程应用实践证明,它仍然存在维护周期短,维护困难和维护成本高的明显不足。本文探讨的原位处理法走的是”中庸”技术路线,试图保持两者的优势,同时又克服两者的不足,也就是同时把制造成本和维护成本都降下来。依靠技术创新,我们正在接近这个理想目标。     

基于联机分析与数据挖掘的电力负荷分析系统

为从大量负荷数据中挖掘有价值的知识,运用联机分析和数据挖掘技术构建了一个电力负荷分析系统。该系统在电力负荷立方体基础上,通过选择有效的预测及匹配算法与联机分析有机结合,共同实现了电力负荷的在线预测和相似模式挖掘。重点介绍了该系统的体系结构、功能以及实现的关键技术。实际应用表明,该系统界面友好、交互性强,可在线、灵活和深入地对负荷进行分析,辅助调度员进行决策。     

Automatic contrast adjustment for detail recognition in SEM images using on-line digital image processing

A new digital filter method has been developed for enhancement of detail recognition in SEM images of high signal-to-noise ratio using an on-line digital image processing system. The filter allows an automated improvement of the presentation of SEM image information and utilizes a median filter of very large mask size and histogram equalization. Since the method can be performed without input of any processing parameters, the user simply pushes a button for obtaining the processing result similar to conventional photo recording. The method utilizes digital signal processors for establishing high speed, hence, the processing results can be immediately assessed. When Applied to a variety of field-emission SEM images, there were no problems with inconvenient artifact encountered.     

铝酸钠溶液在线检测系统的研制

介绍了溶液在线分析系统的测定原理和系统结构。对数学模型的修正作了详细讨论。程序运算得到的溶液浓度值与化验室分析值的相对误差不超过± 2 .5 % ,测量结果的精度能满足生产工艺的要求 ,对生产具有现实的指导意义     

Fractal analysis of two-photon microscopic images for diagnosis of nasopharyngeal cancer

In this study, two-photon microscopy (TPM) was applied to obtain high-resolution, optically sectioned images with cellular morphology information from normal and cancerous nasopharyngeal tissue. Notable difference of nuclear-cytoplasmic ratio was found between these two groups. In particular, fractal dimension (FD) analysis based on TPM images showed good differentiation between normal and cancerous nasopharyngeal tissues. Our results indicate that TPM coupled with FD analysis methods has the potential to extract diagnostic features for label-free histological diagnosis.     

A novel and effective multistage classification system for microscopic starch grain images

This article presents a novel and effective multistage system for classifying Chinese Materia Medica microscopic starch grain images. The proposed classification system is constructed based on the Gaussian mixture model‐based clustering, the feature assignment algorithm, and the similarity measurement. Several features for each starch grain image are extracted and every class of drug is represented by a set of characteristic features. For each stage of the system, only one feature is chosen and assigned to that stage via the feature assignment algorithm, and the corresponding characteristic features are subdivided into smaller subsets based on clustering techniques. At the final stage, each subset contains a certain class of drugs (with corresponding characteristic features) and similarity measurement is carried out for starch grain classification. Three sets of the current state‐of‐the‐art starch grain features including the granulometric size distribution, the chord length distribution, and the wavelet signature are used to construct the system. Experimental results on a database of 240 images of 24 classes of drugs reveal the superior performance of the multistage system. Comparison with the traditional starch grain classification approaches indicates that our proposed multistage method produces a marked improvement in classification performance. Microsc. Res. Tech. 2009. © 2009 Wiley‐Liss, Inc.     

A computer system for on-line image capture and analysis

A computer control system for electron microscopy is proposed; it consists of functionally distinct microprocessors communicating via a central microprocessor (the supervisor) by direct memory access or a common data bus. The control functions such as digital beam scan, accelerating voltage, focusing, etc., are controlled by distributed microprocessors under the direction of the supervisory microprocessor. The system includes a framestore for image storage and a special high speed processor that contains a microcode library of functions. The system is used for interactive real-time image analysis by comparison of calculated images and processed experimental images.     

Minima equalization: A useful strategy in automatic processing of microscopic images

Specifically stained features in microscopic images rarely have a unique range of grey levels which would permit selection of the features by simple thresholding. The spaces between features and immediately surrounding them are often as dark or darker than the more lightly stained features. An algorithm for minima equalization which facilitates the extraction and segmentation of such features was designed and is explained in intuitive terms. It is applied to the analysis of cross-sections of peripheral myelinated nerve fibres. It is shown that the binary image obtained can be combined with a gradient image to give a binary image which accurately reflects the thickness of the myelin in the original image. Using silver-impregnated nerve endings and bile canaliculi stained for thiamine pyrophosphatase, binary images like those prepared manually from thick specimens using a camera lucida can be obtained using the minima equalization procedure. The image processor is used to develop a composite image by combining images at various focal planes through the thick specimen. This image is then processed to obtain the binary image.     

在线分析系统的广义抗干扰研究

在线气体分析技术的本质和根本目的就是连续计量的准确度,而各种原因和形式的干扰使计量准确度很难保障。从工程应用实践出发,在干扰组分干扰、样气处理干扰、电气干扰等三个相关领域研究干扰的来源,干扰影响误差的定量分析以及抗干扰的措施,进而有效保障和提高计量准确度,是十分紧迫的工程技术课题。现在已经积累和取得了许多有现实操作性的进展,本文是在线气体分析工程技术广义抗干扰的综述性总结。     

金属腐蚀在线监测系统的研制

基于电化学线性极化和弱极化测定方法，本文设计了一种金属腐蚀速率在线监测系统．成功地实现了金属腐蚀速率和极化电阻的自动在线监测和实时数据显示。对比实验表明．监测系统性能稳定．测量速度快、测量结果可信。     

An image processing pipeline to detect and segment nuclei in muscle fiber microscopic images

Muscle fiber images play an important role in the medical diagnosis and treatment of many muscular diseases. The number of nuclei in skeletal muscle fiber images is a key bio‐marker of the diagnosis of muscular dystrophy. In nuclei segmentation one primary challenge is to correctly separate the clustered nuclei. In this article, we developed an image processing pipeline to automatically detect, segment, and analyze nuclei in microscopic image of muscle fibers. The pipeline consists of image pre‐processing, identification of isolated nuclei, identification and segmentation of clustered nuclei, and quantitative analysis. Nuclei are initially extracted from background by using local Otsu's threshold. Based on analysis of morphological features of the isolated nuclei, including their areas, compactness, and major axis lengths, a Bayesian network is trained and applied to identify isolated nuclei from clustered nuclei and artifacts in all the images. Then a two‐step refined watershed algorithm is applied to segment clustered nuclei. After segmentation, the nuclei can be quantified for statistical analysis. Comparing the segmented results with those of manual analysis and an existing technique, we find that our proposed image processing pipeline achieves good performance with high accuracy and precision. The presented image processing pipeline can therefore help biologists increase their throughput and objectivity in analyzing large numbers of nuclei in muscle fiber images. Microsc. Res. Tech. 77:547–559, 2014. © 2014 Wiley Periodicals, Inc.     

A digital system for producing X-ray images with a high spatial resolution

A system for detecting X-ray shadowgraphs with a high spatial resolution, in which a shadowgraph formed on a luminophor is transferred to a charge-coupled device (CCD) matrix by using an objective lens, is considered. The signal stored on the CCD matrix is read, converted, and transmitted to the computer for further processing and representation. A 25-lp/mm spatial resolution was obtained for a 10.8 × 10.8-mm input field of the system. The measurements were performed by using a tungsten-wire standard placed on the surface of the input field of the detecting system, when the anode voltage was 45 kV, the anode current was ～2 mA, and the focal distance was 450 mm. It was shown that the 25-lp/mm spatial resolution is not limiting and that it is possible to attain a value of 40 lp/mm or higher.     

在线图像可视铁谱成像系统的像面照度均匀性

为了定量评价在线图像可视铁谱(OLVF)成像系统的像面照度均匀性,建立了一种像面照度模型。以像方参数及放大倍率表征物方视场,将物方视场区域离散化,采用朗伯余弦理论建立入瞳模式的像面照度模型,实现了像面照度的计算与均匀性评价。利用Matlab进行了物面照度仿真分析,确定了OLVF成像系统环形阵列光源的发光二极管(LED)数量,基于像面照度分析确定了最佳成像焦距和放大倍率。计算了油腔通油情况下成像系统中的光能量损耗以及磨粒沉积面的照度分布,建立了油液吸光系数与CCD像面轴上像点照度的关系。结果显示:LED发光强度已知时,仿真计算的像面不均匀度约为5.60%,实际测试的像面不均匀度为8%~9%,满足不均匀度≤10%的要求。开展了磨粒铁谱图像采集实验,结果表明:图像中磨粒清晰可辨,便于图像分割与视觉特征提取。提出的模型可定量描述OLVF成像系统的像面照度,可作为优化系统结构,提高系统成像性能的依据。