利用图像对比度进行显著目标检测

为了对复杂自然场景中各类显著目标进行准确的检测,提出了一种基于图像对比度的检测方法。首先利用全局对比度算子对图像进行检测得到全局对比度显著图,再利用局部对比度算子进行检测得到局部对比度显著图,对局部对比度显著图再做边缘处理和形态学膨胀,然后用全局对比度算子对其紧凑化得到最后的局部对比度显著图。融合全局和局部对比度显著图并加入一定的先验知识得到最后的显著目标图。实验表明该方法性能超过了现有大多数显著目标检测方法。     

太赫兹医学成像研究进展

太赫兹波所具有的无损性以及大量生物分子在太赫兹频段的指纹特性,使其在医学成像领域有着良好的应用前景。本文首先简要概述了太赫兹的医学成像技术手段,其次分别介绍了太赫兹在离体、活体组织中成像的研究现状。生物组织中的水会对太赫兹波产生强吸收,使得成像对比度受限。目前,为了减少组织中的水对成像的影响,针对离体组织的太赫兹成像大多需要进行切片、脱水等预处理,活体中的成像则主要应用在浅表组织。文章重点介绍了活体成像中有望提高太赫兹成像对比度的纳米粒子造影剂,最后对太赫兹医学成像的发展进行了展望。     

X射线影像对比度细节体模的设计

为了评价医用X射线摄影影像质量,设计及制作了一种对比度细节体模。利用X射线透过物质时其透过剂量随物质厚度的增加呈指数减弱原理,在与肌肉组织对X射线减弱特性基本等效的有机玻璃板上加工不同大小和深度的圆孔而制成。对比度细节圆孔在对比度阈值区域精密分布,对比度细节从0.3～80.0mm,同时提出了对比度细节体模影像质量指数的计算方法及体模的应用。该体模使用方便,指标计算简单,适合对X射线影像质量的对比度及空间分辨率的综合评价。     

Morphological contrast index based on the Weber's law

In this article, a morphological contrast index based on the Weber's law is proposed to quantify the contrast in a processed image. This measure involves the contours of the image along with its background. The proposal made here is applied to detect the image with higher contrast, and also identify the enhanced image most similar to the original. Moreover, the contrast index is compared with other four indexes reported in the current literature. © 2012 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 22, 137–144, 2012     

Residual spatial entropy-based image contrast enhancement and gradient-based relative contrast measurement

This paper proposes a novel algorithm to achieve both global and local contrast enhancement using a new definition of residual spatial entropy of gray levels of an image. Residual spatial entropy is utilized to assign a weight to each gray level which is further used in mapping of input gray levels to output gray levels to achieve global contrast enhancement. A non-linear mapping is applied on transform-domain coefficients of image enhanced globally to perform local contrast enhancement. The algorithm allows to control levels of perceived global and local contrast. New definitions of full-reference relative contrast measures are also introduced. Experimental results show that proposed algorithm produces better or comparable contrast-enhanced images than several state-of-the-art algorithms.     

The usefulness of MR subtraction technique in metastatic spinal cancer

Abstract

In this study, the authors examined the usefulness of subtraction techniques in vertebral cancer patients by comparing contrast enhanced images with before/after contrast enhancement subtraction images. In patients with metastatic vertebral cancer, contrast enhanced images and subtraction images were acquired in sagittal and axial planes. On sagittal planes, between the first and the fifth lumbar vertebrae, in three areas of metastatic vertebral cancer and in areas above and below areas with vertebral cancer, signal to noise ratios (SNRs) and contrast to noise ratios (CNRs) were measured. On axial planes, in five vertebral cancer areas, right and left vertebral arches, and right and left longest muscle areas, SNRs and CNRs were also measured. In sagittal planes, when images were divided into contrast enhanced images and subtraction images, SNRs were relatively decreased in the areas above and below vertebral cancers. On axial planes, SNRs were relatively reduced in the right and left vertebral arch and right and left longest muscle areas. On both sagittal planes and axial planes, CNRs were relatively increased in areas with vertebral cancer, and relatively increased on subtraction images. This study shows that before/after contrast enhancement subtraction images can be used for the evaluation of malignant tumours in metastatic spinal cancer.     

靶标对比度测量与调制度研究

本文介绍了一种新型校飞靶标研制工作中表面对比度的测量以及与测量相关的调制度的计算方法。讨论分析了靶标表面两种测量方式的结果,还着重讨论了与测量相关的两种调制度的计算方法,将1931CIE—XYZ系统的明度值引入调制度的计算,提出了分波段计算调制度的观点。研制的靶标经实际使用,很好的满足了要求。     

人眼对比敏感度函数测量方法研究

根据对比度及对比敏感度函数的定义,提出了一种基于积分球和特制调光器产生人眼对比敏感度测试目标的方法,搭建了人眼对比敏感度函数自动化测量系统。该系统采用交叉阶梯法进行心理物理学实验,可以实现人眼对比敏感度函数的测量,可测量的空间频率包括0.8,1.5,2.0,3.0,4.5,6.0,12.0和18.0周/(°),对比度测试目标背景亮度示值误差±5%,对比度重复性0.001,复现性0.004,均满足人眼对比敏感度函数的测量要求。     

Brightness preserving bi‐level fuzzy histogram equalization for MRI brain image contrast enhancement

In this article, brightness preserving bi‐level fuzzy histogram equalization (BPFHE) is proposed for the contrast enhancement of MRI brain images. Histogram equalization (HE) is widely used for improving the contrast in digital images. As a result, such image creates side‐effects such as washed‐out appearance and false contouring due to the significant change in brightness. In order to overcome these problems, mean brightness preserving HE based techniques have been proposed. Generally, these methods partition the histogram of the original image into sub histograms and then independently equalize each sub‐histogram. The BPFHE consists of two stages. First, fuzzy histogram is computed based on fuzzy set theory to handle the inexactness of gray level values in a better way compared to classical crisp histograms. In the second stage, the fuzzy histogram is divided into two sub‐histograms based on the mean intensities of the multi‐peaks in the original image and then equalizes them independently to preserve image brightness. The quantitative and subjective enhancement of proposed BPBFHE algorithm is evaluated using two well known parameters like entropy or average information contents (AIC) and Feature Similarity Index Matrix (FSIM) for different gray scale images. The proposed method have been tested using several images and gives better visual quality as compared to the conventional methods. The simulation results show that the proposed method has better performance than the existing methods, and preserve the original brightness quite well, so that it is possible to be utilized in medical image diagnosis.     

On coherence in neutron imaging

The variety of imaging signals in neutron radiography and tomography became quite large compared to the pure absorption and scattering contrast in neutron radiographies and topographies in the early sixties or seventies of the last century. The diversity of absorption based techniques for neutron radiography and tomography is comparable to coherence based imaging techniques such as phase contrast, differential phase contrast, dark field imaging, diffraction enhanced contrast, refraction contrast, ultra small angle scattering contrast, grating interferometry and crystal interferometry, also the spin of the neutron was successfully used for imaging [1], [2], [3], [4], [5], [6], [7], [8], [9], [10], [11] and [12]. We show which effects (total reflection, diffraction, refraction) contribute to e.g. a step boundary or a phase boundary. Taking this simple object, one can learn to understand the imaging procedure and what is displayed in a radiograph.     

Inorganic Nanoparticles for MRI Contrast Agents

Various inorganic nanoparticles have been used as magnetic resonance imaging (MRI) contrast agents due to their unique properties, such as large surface area and efficient contrasting effect. Since the first use of superparamagnetic iron oxide (SPIO) as a liver contrast agent, nanoparticulate MRI contrast agents have attracted a lot of attention. Magnetic iron oxide nanoparticles have been extensively used as MRI contrast agents due to their ability to shorten T2* relaxation times in the liver, spleen, and bone marrow. More recently, uniform ferrite nanoparticles with high crystallinity have been successfully employed as new T2 MRI contrast agents with improved relaxation properties. Iron oxide nanoparticles functionalized with targeting agents have been used for targeted imaging via the site‐specific accumulation of nanoparticles at the targets of interest. Recently, extensive research has been conducted to develop nanoparticle‐based T1 contrast agents to overcome the drawbacks of iron oxide nanoparticle‐based negative T2 contrast agents. In this report, we summarize the recent progress in inorganic nanoparticle‐based MRI contrast agents.     

超顺磁性纳米氧化铁的制备、表面修饰及其在磁共振成像造影剂方面的应用

介绍了磁共振成像技术(MRI)和MRI造影剂的应用原理,综述了近年来超顺磁性纳米氧化铁(SPIO)的制备方法,包括化学沉淀法、水热法、微乳液法、溶胶-凝胶法和高温分解法等,以及SPIO在造影剂方面的应用,并展望了其今后的发展方向。     

Testing dispersion effects from general unreplicated fractional factorial designs

Continuous improvement of the quality of industrial products is an essential factor in modern‐day manufacturing. The investigation of those factors that affect process mean and process dispersion (standard deviation) is an important step in such improvements. Most often, experiments are executed for such investigations. To detect mean factors, I use the usual analysis of variance on the experimental data. However, there is no unified method to identify dispersion factors. In recent years several methods have been proposed for identifying such factors with two levels. Multilevel factors, especially three‐level factors, are common in industrial experiments, but we lack methods for identifying dispersion effects in multilevel factors. In this paper, I develop a method for identifying dispersion effects from general fractional factorial experiments. This method consists of two stages. The first stage involves the identification of mean factors using the performance characteristic as the response. The second stage involves the computation of a dispersion measure and the identification of dispersion factors using the dispersion measure as the response. The sequence for identifying dispersion factors is first to test the significance of the total dispersion effect of a factor, then to test the dispersion contrasts of interest, which is a method similar to the typical post hoc testing procedure in the ANOVA analysis. This familiar approach should be appealing to practitioners. Copyright © 2001 John Wiley & Sons, Ltd.     

博物馆体验研究的国内现状及趋势分析

目的 对国内外博物馆体验研究的文献进行计量可视化分析,以便客观真实地了解现阶段博物馆体验研究的重点和动态。方法 运用Citespace可视化分析工具对CNKI核心数据库中2000—2022年博物馆体验及Web of Science数据库中核心合集期刊进行量化分析和质化论述,内容包括发文时间、关键词聚类、发文刊物分布、国内外研究侧重点论述、研究共性及差异解读。结论 检索范围内国内外博物馆体验研究发文数量呈快速上升趋势,中文发文刊物主要分布在艺术设计领域,国外发文刊物集中在博物馆学研究领域;国内外研究热点都涉及新媒体技术、文化旅游发展、观众研究方面,但国内主要围绕新媒体技术在展示设计中的应用、观众体验的跟踪调查研究和文旅融合下的游客研究,国外研究主要侧重于数字媒体技术对博物馆休闲娱乐氛围的营造、博物馆中的集体学习体验、文化旅游中博物馆的真实性表达。     

Contrast limited fuzzy adaptive histogram equalization for enhancement of brain images

Contrast limited fuzzy adaptive histogram equalization (CLFAHE) is proposed to improve the contrast of MRI Brain images. The proposed method consists of three stages. First, the gray level intensities are transformed into membership plane and membership plane is modified with Contrast intensification operator. In the second stage, the contrast limited adaptive histogram equalization is applied to the modified membership plane to prevent excessive enhancement in contrast by preserving the original brightness. Finally, membership plane is mapped back to the gray level intensities. The performance of proposed method is evaluated and compared with the existing methods in terms of qualitative measures such as entropy, PSNR, AMBE, and FSIM. The proposed method provides enhanced results by giving better contrast enhancement and preserving the local information of the original image. © 2017 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 27, 98–103, 2017     

图像灰度变换在Photoshop中实现方法的研究

以图象的灰度变换理论为基础,论述了灰度变换关系如何在数字图像处理软件Photoshop中实现.分析了Photoshop中实现灰度变换的levels和curves两种调节工具的具体使用方法,并讨论给出了2种工具不同的适用范围及优缺点.实践表明,利用Photoshop对数字图像进行合理的灰度变换处理具有重要的实际应用价值.     

Single image veiling glare removal

Photographing against a bright light source is difficult since the direct light from the light source causes glare phenomenon in the lens, changing the colour balance and reducing the image contrast within the field of view. To address the effect, we introduce a glare formation model that accounts for the characters of the glare. Based on the model, we propose a single image processing method to remove the glare in the images by decomposing the image into the scene layer and the glare layer. We then adjust the brightness and the colour balance of the scene layer to eliminate the influences of the glare. In order to enhance the contrast decreased by the glare, we use a local standard deviation-based contrast enhancement algorithm to boost the details while avoiding excessive enhancement. Experimental results show that the method removes the majority of the glare and improves the local contrast effectively.     

纳米金在肿瘤诊断中的应用

纳米金具有独特的理化性能,在肿瘤诊断和治疗中取得了许多重要进展。综述了纳米金的结构组成、粒径尺寸、形貌特征对其本身性能的影响,介绍了纳米金对肿瘤标志物的检测和作为造影剂对肿瘤成像的研究进展,着重评述了纳米金应用于体内外肿瘤光学成像方面的研究情况,展望了其未来的发展前景。     

我国与东盟可可制品标准的对比分析研究

本文通过对我国和东盟国家可可制品标准的比对分析,找出了指标差异,提出了相关建议,为提高我国可可制品标准化水平,保证可可制品质量安全提供参考。     

多光谱光声层析技术在肿瘤学中的应用进展

多光谱光声层析技术是一种新兴的光声成像技术,兼具光声断层扫描和多光谱成像的优点。该成像技术需要利用内源性和外源性光声成像对比剂进行成像。成像时,激光发射器发射多个波长的激光束照射组织,组织发生热弹性膨胀并产生超声波,将超声换能器接收的光声信号进行后处理,分解光谱信息并重建图像。目前,多光谱光声层析技术已广泛用于多种肿瘤的研究。文章着重介绍光声成像对比剂和多光谱光声层析技术的发展近况以及在临床转化中取得的研究进展。