一种实现共焦显微镜空间微分成像的新方法

提出了一种实现共焦显微镜空间微分成像的新方法。为了获得空间微分图像,首先利用时间分辨技术结合互补调制技术,获得两束相位相反的调制光,然后利用这两束相位相反的调制光结合共焦扫描技术,实现共焦显微镜的空间微分成像。实验表明:这种空间微分技术可以准确实现共焦显微镜的空间微分成像,从而获得成像物体的边缘轮廓和实现边缘增强。     

Study of inhomogeneities of extended media by the method of passive-active radiometry in the millimeter wavelength range

We present the results of studies of backscattering characteristics of extended inhomogeneous media using a passive-active complex of near-field radio-wave imaging. The complex includes an 8-mm wavelength radiometer, a focusing antenna system, and a system of illumination of studied objects by a wideband noise signal. This radiometric complex is intended for the formation of a high-resolution radio image of the internal structure of spatially inhomogeneous media explored at distances commensurable with the size of the antenna aperture. The system of radio-wave imaging can be used for medical and biological studies of a human body and detection of extended objects hidden under the surface of a medium not transparent for visual observation, but partially transparent in the operating wavelength range.     

基于FPGA联合Sobel算法的实时图像边沿检测系统的设计与实现

边沿检测技术作为数字图像处理领域的重要一支,在目标匹配,交通管控,国防安全等多个领域有着广泛的应用,能够精确高效地实现边沿检测对于后续进行更高层次的图像识别以及图像处理有着密切的联系。为了实现实时有效的图像边沿检测提出了基于FPGA结合Sobel算法的实时图像边沿检测系统,硬件使用流水线结合并行处理的解决方案,能够有效提高图像处理的速度;算法设计采用Sobel算法,不但简化了运算同时获得了不错的检测效果。实验结果显示,系统可高效地达成实时图像边沿检测的设计目的,而且提升了图像的处理效率与边沿检测的效果,便于满足后续图像处理的要求。     

像增强器视场缺陷检测方法研究

在数字式像增强器性能综合检测系统的基础上，研究了像增强器视场缺陷的检测方法。通过数字视频摄像机采集缺陷图像，利用数字图像处理方法确定缺陷性质，缺陷处理算法基于图像灰度特征而不是边缘特征提取。该方法适用于对检测对象有具体量化和定位要求，而不是简单的只有数量和形状特征要求的场合。实验表明，该检测方法能够较准确地检测像增强器的缺陷。     

红外偏振成像对伪装目标的探测识别研究

针对目前普通光电成像系统对伪装目标的探测和识别概率较低的状况,提出伪装目标的探测识别新技术研究。介绍了红外偏振成像系统的原理、组成和特点,研制的中波/长波红外偏振成像装置,其波段范围为3 m ~5 m和8 m~12 m,线偏振度95%,消光比大于100∶1,给出了试验分析数据和偏振融合效果图。研究表明,采用红外偏振成像技术可以有效地实现对地面伪装目标的探测和识别。研究结果还可以扩展到对人工假目标、空中隐身目标等的探测和识别。     

Optical Imaging System with LaserGated Brightness Amplifier

l.IntroductionTheideaofusingahigh-gainactivemediumtoformbrightness-enhancedmicroscofr-.icimageswasproposedmorethan2oyearsago[1:.Introductionofbrightnessamplifierintousua1oPticalsystemwouldPermittoovercomethewellknownrestrictionaccordingtowhichthebrightnessattheoutputoftheopticalsystemcannotexceedthatatthein-put[zJ.SomepulsedmetalvaporlaserssuchasthecopPervaPOrlaser(CVL)havebeenusedasimage-brightnessamplifiersinvariousopticalprojectionsystem[3j-lnthiscase,wecanbenefitfromthattheactivemedium…     

光谱编码成像系统的数据压缩技术

利用时间拉伸显微成像系统观察并记录非重复动态随机现象,在其超高成像速度和高空间分辨率下必定会产生大量的数据。一种基于差分检测和游程编码的数据压缩方法,可以有效地解决时间拉伸成像系统的数据存储问题。差分检测可以消除连续相同的信号,只检测出相邻信号的差异,从而提高游程编码算法的有效性。实验中,采用扫描频率为77.76 MHz的时间拉伸显微成像对分辨率板、人红细胞和人乳腺癌细胞线性扫描成像。实验结果表明,数据压缩比可以达到8.47,对比分析发现经过差分检测方法可以获得更高的压缩比。另外,通过计算重建后的图像与原图的结构相似性(SSIM)值发现,经过数据压缩后高质量的图像可以被重建。     

Parallel performance of the fine-grain pipeline FPGA image processing system

The use of FPGA circuits in imaging systems increases. They compete with other computing environments. The article describes the indications to be followed while choosing the type of image processing computing system taking under consideration the advantages and disadvantages of each technology: general purpose processor, digital signal processor, graphical processing unit, application specific Integrated circuit and field programmable gate array. Attention is drawn to various video transmission standards. The state of research and development trends in the field of FPGA-based image processing are briefly presented. A defining processing performance method for image processing is proposed. It is proven that for a pipeline architecture implemented in FPGA, a linear speedup is achieved and parallel efficiency is equal to one.     

Optimization of sparse synthetic transmit aperture imaging with coded excitation and frequency division

An effective aperture approach is used for optimization of a sparse synthetic transmit aperture (STA) imaging system with coded excitation and frequency division. A new two-stage algorithm is proposed for optimization of both the positions of the transmit elements and the weights of the receive elements. In order to increase the signal-to-noise ratio in a synthetic aperture system, temporal encoding of the excitation signals is employed. When comparing the excitation by linear frequency modulation (LFM) signals and phase shift key modulation (PSKM) signals, the analysis shows that chirps are better for excitation, since at the output of a compression filter the sidelobes generated are much smaller than those produced by the binary PSKM signals. Here, an implementation of a fast STA imaging is studied by spatial encoding with frequency division of the LFM signals. The proposed system employs a 64-element array with only four active elements used during transmit. The two-dimensional point spread function (PSF) produced by such a sparse STA system is compared to the PSF produced by an equivalent phased array system, using the Field II simulation program. The analysis demonstrates the superiority of the new sparse STA imaging system while using coded excitation and frequency division. Compared to a conventional phased array imaging system, this system acquires images of equivalent quality 60 times faster, when the transmit elements are fired in pairs consecutively and the power level used during transmit is very low. The fastest acquisition time is achieved when all transmit elements are fired simultaneously, which improves detectability, but at the cost of a slight degradation of the axial resolution. In real-time implementation, however, it must be borne in mind that the frame rate of a STA imaging system depends not only on the acquisition time of the data but also on the processing time needed for image reconstruction. Comparing to phased array imaging, a significant increase in the frame rate of a STA imaging system is possible if and only if an equivalent time efficient algorithm is used for image reconstruction.     

高光谱成像技术无损检测赣南脐橙表面农药残留研究

高光谱成像技术具备图像和光谱的双重优势,作为一种快速无损检测分析技术,检测过程无损、无污染和无接触。高光谱成像数据包括样本的图像信息和光谱信息,采集样本高光谱成像数据时,样本的每个像素点都有一条光谱与之对应,样本的每个波长都有一幅灰度图像与之对应。研究采用高光谱成像技术无损检测不同稀释浓度的农药在赣南脐橙样品表面残留随时间变化的关系。用蒸馏水把农药分别配置成1∶20, 1∶100和1∶1 000倍的溶液。然后把不同浓度的溶液滴到30个洗净的脐橙表面, 将涂有农药的脐橙分别放置0,4和20 d,然后采集在900～1 700 nm波长范围的高光谱成像原始数据。通过主成分分析获取930,980,1 100,1 210,1 300,1 400,1 620和1 680 nm共8个特征波长,基于这些特征波长做第二次主成分分析,应用PC-2图像并经过适当的图像处理方法对不同浓度及放置不同天数的农药残留进行无损检测。采用高光谱成像技术检测三个时间段较高稀释浓度的果面农药残留都比较明显。高光谱成像技术作为一种检测方法,可用于评价各个时间段较高浓度的农药残留。     

基于成像机理的小波包变换多聚焦图像融合

由于可见光成像系统的聚焦范围有限,因而在成像过程中,除聚焦良好的物体能生成清晰的图像外,该物体前后一定距离外的所有物体都将呈现不同程度的模糊.为了获得场景内所有物体均清晰的图像,在分析了多聚焦图像成像机理的基础上,提出了一种基于小波包变换的融合方法.它是将成像系统先聚焦在一部分对象上,得到其清晰的图像;然后再将其聚焦在另一部分对象上,得到另一清晰的图像;最后把这两幅实验图像加以融合,从而获得场景内所有物体均清晰的图像.实验结果表明,基于小波包变换的融合方法能够将信号的频带进行多层次划分,对高频成分也能进一步地分解,可有效综合多聚焦图像.     

Photoacoustic Tomography of Biological Sample Using Phase-controlled Focus Algorithm

Photoacoustic (PA) imaging is a new imaging modality, which converts pressure signals received by a scanning detector to a local distribution of electromagnetic absorption density. In this paper an experiment result of a photoacoustic tomography to depths of ～7 mm for a real tissue is presented, using a 532-nm pulse YAG laser. The time-resolved stress detection technique was used for PA signal detection with a high temporal resolution. A phase-controlled focus algorithm was used for image reconstruction. Images of different depth profiles in tissue were obtained. The depth resolution was 30 μm and could be up to 10 μm using a wide-band tranducer.     

菲涅耳望远镜合成孔径激光成像雷达实验室验证

对菲涅耳望远镜合成孔径激光成像雷达进行了实验室尺度条件下的原理验证实验。实验中利用不同曲率半径、垂直正交偏振的两个球面波通过二维(2D)扫描方式照明远距离处的目标,接收望远镜接收到的目标回波经过偏振分光镜分成两束作为信号光和本振光进入2×4 90°桥接器,桥接器输出的四路光信号被两个平衡探测器接收,平衡探测器输出电信号经模数转换后经过复数化、两维相位二次项匹配滤波算法处理后可以重构出目标图像。对4.3m处点目标和2D面目标进行了成像实验,取得了具有良好成像分辨率和对比度且带有散斑效应的预期成像结果,证明了该合成成像激光雷达概念的正确性。     

Photoacoustic Tomography of Biological Sample Using Phase-controlled Focus Algorithm

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利用DMD获取高动态范围图像技术

高动态范围的图像可用于同时探测具有较大对比度的亮暗目标,利用数字微镜(DMD)获取高动态范围图像是目前最为先进的一种技术。本文在分析DMD工作原理的基础上,设计了一种像素级的高动态范围图像获取系统,该系统由光学系统、机械系统、DMD像素级调光算法及成像单元组成。光学系统采用二次成像光路,其中第一次成像物镜采用像方远心光路,第二次成像的转置镜头采用放大倍率近似1: 1的准对称结构,机械系统采用光学元件的包边设计和定心车工艺,达到秒级的光学装配精度;DMD像素级调光算法采用搜索单个微镜像素在图像帧周期间的控制权值实现,成像单元可同时兼顾科学级12 bit sCMOS和8 bit CCD,设计完成的原理样机验证了系统设计的正确性,其获取的图像动态范围可达140 dB以上,远高于传统摄像机78 dB的动态范围。     

微型X射线数字成像系统的测试与应用

研制了一套采用X射线敏感CCD作为成像探测器的微型数字成像系统并用于牙科诊断。应用牙齿模型与分辨率测试卡对系统的辐射剂量和分辨率进行了测试,采用分段线性校正对CCD与转换屏耦合下的响应不均匀性进行校正,并通过计算线性相关系数辨别瑕疵像元以避免误判。测试了系统在高分辨率、小工作幅面X射线检测方面的应用效果。结果显示,系统分辨率高于10lp/mm,在获得相近对比度图像的条件下,所需的辐射剂量仅为胶片的10%,图像非均匀性相对校正前可降低27.5%。得到的结果表明,系统满足高分辨率、低辐射剂量的使用要求,在微小物体X射线检测方面具有较大的应用潜力。     

电光调制在被动综合孔径成像探测中的应用

介绍了一种新型被动综合孔径成像探测方法:视场辐射信号被接收和放大后,通过电光幅度调制将其幅度和相位信息加载到光波上,经光纤传输在末端形成阵列,通过光学系统直接成像,将视场实时恢复出来.该方法可实现工作在微波、毫米波和太赫兹波段的高分辨力实时成像探测的目的.深入分析了电光调制器在综合孔径成像探测中的应用,建立电光调制模型,讨论了在小信号调制下的电光幅度调制近似理论.通过数值计算与仿真分析,得到综合孔径成像探测中电光调制器的调制信号强度限制的有关结论.结果表明,利用上变频电光调制技术和光信息处理,所得到的成像仿真图的半峰全宽和信噪比性能都优于传统的基于下变频技术的成像仿真结果.     

异型传像光纤束在光电探测系统中的应用

传像光纤束在通讯、医疗、军事、光电探测等领域具有广泛的应用,光电系统与传像光纤束相结合可以简化系统设计,增加系统的灵活性。异型传像光纤柬可以实现信号排列的传输变换,其中最常见的变换是图像重组,重组后的图像通过光电探测器将信号读出,送入后端信号处理系统获得目标信号。从空间应用红外光谱仪、高帧频火焰温度探测和光电成像探测三个系统中异型传像光纤束实际应用出发,对异型传像光纤束进行了简要的介绍。     

基于USB2.0的智能视频监控系统设计

针对目前流行的视频监控系统不能智能识别、视频传输占用太多网络资源、视频存储容量有限等问题,设计了一种基于USB2.0的智能视频监控系统。该系统通过在线动态更换参考图像,消除了时间变化引起的阳光、天气等因素对背景图像的影响。按照图像识别方法自动检测监控目标,只有当检测到可疑目标后,才把相应的视频信号传输给监控端显示和存储,并同时向监控人员发出报警提示信号。     

Three-dimensional visualization of objects in scattering medium using integral imaging and spectral analysis

This paper presents a three-dimensional visualization method of 3D objects in a scattering medium. The proposed method employs integral imaging and spectral analysis to improve the visual quality of 3D images. The images observed from 3D objects in the scattering medium such as turbid water suffer from image degradation due to scattering. The main reason is that the observed image signal is very weak compared with the scattering signal. Common image enhancement techniques including histogram equalization and contrast enhancement works improperly to overcome the problem. Thus, integral imaging that enables to integrate the weak signals from multiple images was discussed to improve image quality. In this paper, we apply spectral analysis to an integral imaging system such as the computational integral imaging reconstruction. Also, we introduce a signal model with a visibility parameter to analyze the scattering signal. The proposed method based on spectral analysis efficiently estimates the original signal and it is applied to elemental images. The visibility-enhanced elemental images are then used to reconstruct 3D images using a computational integral imaging reconstruction algorithm. To evaluate the proposed method, we perform the optical experiments for 3D objects in turbid water. The experimental results indicate that the proposed method outperforms the existing methods.