基于异步时序的高帧频相机垂直拖尾处理

介绍一种高帧频相机垂直拖尾影响的解决方法,该方法同时考虑连续采集模式下帧间图像和像元合并（binning）技术的影响。与常用的静态图像拖尾处理的算法如逆向逐行修正算法相比,该算法非常适用于连续图像拖尾处理,特别是经过Binning后获取的图像。在某自主研制的基于异步时序的40 000 帧/秒高速相机中应用该方法,有效去除了拖尾影响。最后,运用该方法处理的图像验证了算法的有效性。     

星图中基于小波变换的CCD传感器Smear现象消除方法

帧转移型CCD传感器在拍摄星空背景图像时,视场中高亮度恒星会产生Smear现象,从而对目标检测有严重影响.为了消除Smear现象,提出了一种星图中基于小波变换的Smear消除方法.首先根据Smear产生机理及星空图像特性,建立星图Smear问题的模型|然后使用多层二维Haar小波分解,把Smear亮线分离到低频分量及高频垂直分量中分别进行Smear消除处理|最后重构出消除Smear的图像.实验结果表明:该方法能有效去除Smear,最大限度保留图像原有信息,并可增强Smear区域弱小目标信噪比.     

帧转移型数字相机帧转移模糊的复原

帧转移型面阵CCD相机因其诸多优点而得到了广泛的使用 ,但它也存在帧转移模糊的问题。介绍了CCD相机的几种面阵类型及其各自的一些特点 ,重点介绍了帧转移型面阵器件的工作过程 ,分析了面阵CCD器件帧转移模糊形成的原因 ,并提出了解决帧转移模糊的方法。介绍了用该方法消除帧转移模糊的实例 ,验证了方法的有效性     

星空观测图像目标拖尾的自动消除

为了实现对星空观测图像中高亮目标产生的拖尾现象进行自动消除,建立了目标拖尾自动消除系统,对该系统所采用的图像背景高斯噪声分布参数估计、目标拖尾检测以及图像灰度值校正等算法进行研究。利用直方图最小二乘曲线拟合估计星空观测图像背景高斯噪声的分布参数;利用观测图像中目标拖尾现象的特征提出一种基于统计信息的拖尾检测算法;在确定目标拖尾位置的基础上对被污染的像素进行灰度值校正;利用Visual Studio 2005开发出一套星空观测图像目标拖尾自动消除系统。实验结果表明:针对16 bit,1 0241 024的星空观测图像,单帧图像处理时间约为300 ms,拖尾现象得到消除,恒星和目标等有用信息未被破坏。本文算法基本满足后续观测图像中弱小目标检测稳定、可靠、精度高等要求。     

线阵CCD全饱和单侧拖尾特性分析

在用532nm连续激光辐照TCD-1200D型线阵CCD的过程中,发现了光斑的全饱和单侧拖尾现象。为了分析这种现象的特性,实验测量了拖尾长度随激光功率、CCD积分时间和CCD驱动频率的关系,发现拖尾长度随着激光功率和积分时间的增加而增加,但在一定范围内与CCD驱动频率无关。通过理论计算和实验数据分析拟合发现,拖尾长度和激光功率密度和积分时间的乘积有关,并根据激光辐照下CCD器件光生电荷量的产生过程,推导出了拖尾长度与CCD势阱光生电荷量的关系,得到了拖尾长度随光生电荷量的变化曲线,为全饱和单侧拖尾现象机理分析提供了数据支持。     

CCD成像系统信号处理过程的软件仿真与参数优化

对CCD成像系统的AGC(Automatic Gain Control)、背光补偿、伽玛校正等信号处理过程进行了理论分析,在此基础上,讨论了CCD成像系统信号处理过程的仿真与参数优化方法,编写了相关仿真软件。实验结果表明:所讨论的方法能够实现CCD成像系统信号处理过程的软件仿真,并同时实现相关控制参数的优化。     

平面偏振光场光弹性实时相移法

光弹性法可广泛用于二维、三维应力或应变场的研究。根据偏振相移法的原理,提出一种新的积分相移法,并设计了用于全场等倾线和等差线实时分析的光弹性仪。在正交偏振光场下,按一定速度同步旋转起偏镜和分析镜,CCD摄像机可连续获取四幅相移光弹图像,由CCD像敏单元积分获得其光强值,通过所提出的相移法运算,可以迅速地得出全场等倾角和等差线的相位值。该方法和装置不仅可用于光学原件及玻璃制品的高速检测,而且也可用于随时间缓慢变化的光弹性分析中。     

CCD中激光光斑的全饱和单侧拖尾现象

利用532 nm连续激光辐照以东芝TCD1200D型线阵CCD为图像传感器的扫描相机进行实验,在相机输出视频中发现了光斑拖尾的现象,拖尾有限长、全饱和并且仅在光斑一侧。分析排除了光分布造成拖尾的可能原因。其单侧、有限长的特点不符合像素溢出或漏光造成的拖尾,而与转移损失造成的拖尾一致。但其全饱和的特点,不符合目前转移损失率的常数模型。针对当前体沟道CCD的内部结构和工作原理,提出了一种转移损失率随电荷量变化的模型,对新发现的全饱和单侧拖尾进行了解释。     

基于多次成像的分辨率提高算法研究

在数字成像快速发展的今天,对CCD的分辨约有着越来越高的要求,文中提出了一种新的提高CCD成像分辨率的算法,利用多幅有相对位移的低分辨率图像,通过一定的计算,合成后得到分辨率较高的图像.由于算法与硬件无关,即独立于设备,所以无论CCD硬件发展到如何先进的水平,该算法都有其应用价值的.     

列图像中遮挡缺损图像补偿算法

针对动态图像的遮挡缺损问题,提出了基于图像块的帧间预测算法,可以检测出序列图像中的遮挡缺损区域;利用帧间灰度相关性修正补偿算法进行遮挡缺损区域补偿,利用修正的像元对缺损区域进行补偿能够克服传统插值补偿算法补偿痕迹明显的缺点.仿真结果表明:该算法补偿处理区域与邻域灰度过渡平滑,消除了补偿痕迹,补偿效果比较理想.     

新型分子高光谱成像系统性能分析及数据预处理

将分子成像技术和高光谱技术相结合,研制了基于AOTF(Acousto-optic Tunable Filters)的分子高光谱成像系统。系统由显微镜、分光仪、CCD镜头、图像数据采集卡和计算机等几部分组成。在综合考虑各功能部件的性能及相互的制约关系的基础上,分析了系统的性能指标,系统的光谱范围从550～1 000 nm,可采集200个波段,空间分辨率可达0.061 5 μm,光谱分辨率可达2 nm,当CCD工作在积分模式下采集速度可达到2.612 5 s·B-1,当CCD工作在非积分模式下可达到约0.11 μs·B-1。由于受系统光源和光路中透镜及传感器性能的影响,采集到的图像数据需要进行预处理,文中提出一种空间维和光谱维联合校正的灰度校正系数算法,并给出算法的具体实现。以白血病的血液作样本,通过对比校正前后的单波段图像、伪彩色图像和光谱曲线,说明校正算法的有效性,为后续的光谱图像数据分析提供了有效的数据。     

Joint decision and Naive Bayes learning for detection of space multi-target

In the photoelectric tracking system, the detection of space multi-target is crucial for target localization and tracking. The difficulties include the interferences from CCD smear and strong noise, the few characteristics of spot-like targets and the challenge of multiple targets. In this paper, we propose a hybrid algorithm of joint decision and Naive Bayes (JD-NB) learning, and present the duty ratio feature to discriminate the target and smear blocks. Firstly, we extract the proper features and train the parameters of the Naive Bayes classifier. Secondly, target blocks are preliminarily estimated with the Naive Bayes. Lastly, the 4-adjacent blocks of the candidate target blocks are jointed to analyze the distribution pattern and the true target blocks are secondarily extracted by the method of pattern matching. Experimental results indicate that the proposed JD-NB algorithm not only possesses a high recognition rate of better than 90% for the target block, but also effectively overcomes the disturbance of the smear block. Moreover, it performs well in the detection of small and faint targets when the SNR of the block is higher than about 0.014.     

航天TDI-CCD相机的MTF和像质分析

TDI- CCD相机在航天遥感中得到了越来越广泛的应用 ,但航天 TDI- CCD相机的像移是难以完全消除的或是不可避免的。推导和分析了 TDI- CCD相机的像移以及各种像移的 MTF表达式 ;参照美国国家图像解释分级标准( NIIRS) ,分析了像移量对像质的影响。结果表明 :当采用 96级延迟积分的 TDI- CCD器件时 ,同步误差只有小于 2 % ,成像质量才能得到保证 ,这与滚筒式扫描成像实验结果相吻合     

低曝光条件下遥感相机微振动量检测

针对搭载平台颤振对遥感相机成像的影响,利用辅助高速面阵CCD相机拍摄高帧频图像序列,通过像元合并来补偿曝光时间不足,增加图像的亮度、对比度和信噪比,同时结合一种区域选择算法来选择用于计算的图像区域,最后使用灰度投影算法对振动位移量进行估计.实验数据表明,提出的改进算法误差为一个像元,在准确性和稳定性方面均明显优于原始算法.     

Image restoration for interlaced scan CCD image with space-variant motion blurs

When the speeds of objects in a scene exceed the temporal resolution of the camera shutter, motion blurs will occur. Since objects are often moving in different directions at different speeds, the degradation of a CCD image is often characterized by space-variant motion blurs. Image restoration algorithms for space-variant motion blurs are available for progressive scan CCD images, but not for interlaced scan images. To address the space-variant image restoration for interlaced scan images, a novel three-step image restoration scheme is proposed. Firstly, one interlaced scan image is divided into odd field and even field images. Secondly, these two field images are further segmented into rectangular blocks and the motion vectors are computed based on these rectangular blocks using an efficient block matching algorithm. Thirdly, image restoration is performed using a blind deconvolution algorithm in the odd or even field image. The final restored image is obtained by combining the restored odd and even field images. The scheme is illustrated by restoring a space-variant blurred moving vehicle image and a synthetic blurred image.     

基于普通CCD的每秒百万帧高帧频成像方法

针对CCD图像输出时间长影响其帧频率的问题,提出了一种基于普通CCD实现超高帧频成像的方法.采用掩膜覆盖CCD的光敏区,建立图像的片上存储空间,消除CCD电荷转移输出占用过多时间的影响,可以使普通CCD的帧频达到每秒百万帧频以上.介绍了不同掩膜实现方案的优缺点,讨论了掩膜图像的恢复方法,采用条状孔掩膜方式建立了基于普通CCD的每秒百万帧高帧频成像系统样机,利用氙灯对样机性能进行验证,获得了14幅79×79像素的氙灯发光过程图像,样机帧频率达到了每秒200万帧的超高速度.     

Development of Genetic Algorithm based 3D-PTV technique

A new 3D-PTV technique has been developed using GA (Genetic Algorithm). The measurement system consists of three CCD cameras, Ar-ion laser, an image grabber and a host computer. One-to-one correspondences are made by taking advantage of the combinatorial optimization of the genetic algorithm for the whole particles of the two images during the time interval of image frames. Two fitness functions are introduced in order to enhance the correspondences of the particles. One is based on the concept of continuum theory and the other one is based on the minimum error of threedimensional distance. Performance of the developed algorithm is tested using a set of virtual images constructed by the use of LES data set on an impinging jet. The developed 3D-PTV system is successfully applied to the measurement of flow characteristics of the wake of a circular cylinder.     

Interlaced scan CCD image motion deblur for space-variant motion blurs

Motion blur is caused by camera shakes or object motions during exposure when the shutter speed is relatively slow. As for the object motion blur, the degradation of a CCD image is often characterized by space-variant motion blurs, since objects are often moving in different directions at different speeds. But most image restorations for space-variant motion blurs are addressed only for progressive scan CCD images. To address the space-variant image restorations for interlaced scan images, we propose a novel image restoration scheme. First, one interlaced scan image frame is required, which is divided into the odd field and the even field images. These two field images are further segmented into rectangular blocks. The motion vectors are computed in these rectangular blocks using an efficient block matching algorithm. Second, image restoration is performed in these rectangular blocks using a constrained least square algorithm in the odd or even field image, which can both preserve edge structures and remove noises. Our novel scheme is illustrated by restoring a space-variant blurred moving boat image and a synthetic blurred image.     

声光调制实验的一种CCD成像改进方法

提出了声光调制实验的一种CCD成像改进的实验方法,即声光调制的入射光和衍射光成像于CCD上,对光斑图像进行编程处理,计算机给出光斑的位置。给出了实验步骤、图像处理算法和实验结果。     

A fast onboard star-extraction algorithm optimized for the SVOM Visible Telescope

The Space multi-band Variable Object Monitor (SVOM) is a proposed Chinese astronomical satellite, dedicated to the detection, localization and measurement of gamma-ray bursts (GRBs) on a cosmological scale. An efficient algorithm is developed for the purpose of onboard star extraction from the CCD images obtained with the Visible Telescope (VT) onboard the SVOM. The CCD pixel coordinates of the reference stars will be used to refine the astronomical position of the satellite, which will facilitate triggering rapid ground-based follow-up observations of the GRBs. In this algorithm, the image is divided into a number of grid cells and the “global” pixel-value maximum within each cell is taken as the first-guess position of a “bright” star. The correct center position of a star is then computed using a simple iterative method. Applying two additional strategies, i.e., scanning the image only by even (or odd) lines or in a black-white chess board mode, we propose to further reduce the time to extract the stars. To examine the efficiency of the above algorithms, we applied them to the experimental images obtained with a ground-based telescope. We find that the accuracy of the astronomical positioning achieved by our method is comparable to that derived by using the conventional star-extraction method, while the former needs about 25 times less CPU time than the latter. This will significantly improve the performance of the SVOM VT mission.