CCD摄像机全自动调光系统

在CCD摄像系统中,利用电子快门和可变光阑有机结合,在单片机控制下实现全自动调光,不仅扩大了调光的动态范围,而且可有效地控制对运动目标摄像时产生的像移,其最大像移控制在0.0024mm.这些方法应用到使用空间受到限制的小型电视摄像系统中具有现实意义.     

Microscopic spectral imaging using a video camera

A technique is described which permits the simultaneous acquisition of multiple fluorescent emission and/or absorption spectra from discrete regions of a specimen under microscopic observation. The instrument consists of a modified inverted microscope, an optical diffraction grating, a silicon intensified target (SIT) camera, and a digital video image processor. Observation of the zero diffraction order of the grating with the SIT camera permits an optical slice of the specimen to be selected by positioning the region of interest over the entrance slit of the grating housing. To obtain the spectral characteristics of this optical slice, the grating is rotated to impinge the first order diffraction on the camera. The video image of this first order diffraction maintains spatial integrity along the slit's long axis and provides spectral dispersion on the perpendicular axis. Thus, each of the horizontal video lines along the long axis of the slit represents a spectral analysis of the corresponding spatial location within the specimen. The spectral resolution (0.2 nm/channel) of each video line is determined by the resolution of the camera system in conjunction with the resolution of the grating. The image processing system acquires and processes all 500 spectra in 33 ms and permits the accurate localization of the source of each spectrum in the slice. This type of topological spectral analysis permits the determination of both spatial and spectral characteristics of intrinsic or extrinsic chromophores within the specimen. In addition, this technique permits the detection of and the possible correction for photobleaching, light scattering and image plane effects. The application of this technique to the study of single cells is discussed and an example of the technique in determining the fluorescence spectra of acridine orange within the nucleus of an intact mammalian blastocyst is described.     

In-situ water level measurement using NIR-imaging video camera

Water level is a critical component for observation and management of water resources. Since video surveillance is becoming a standard configuration of gauging stations, more attentions have been paid on the image-based water level measurement techniques in recent years. Instead of human eyes, images of staff gauge can be captured by a camera and automatically processed to detect the readings of water line. However, it is quite unreliable to identify the readings on staff gauges due to low imaging resolution, tilt viewing angle and complex illumination in field conditions. For that reason, most of the existing methods failed to make effective automatic measurements in practice. To resolve difficulties of poor visibility, image distortions and ambient noises in in-situ water level measurement with standard bicolor staff gauges, an all-weather, real-time and automatic flow measurement system using single near infrared (NIR)-imaging video camera is developed. Lab and in-situ experiments demonstrate that NIR-imaging is efficient to enhance image contrast and suppress reflection noises on the water surface, which successfully overcomes the limitation of water line detection with current visible light (VIS)-imaging systems in clear water and low velocity conditions. The proposed water level conversion method is based on image ortho-rectification. It requires no on-site calibration by utilizing natural corresponding points to build the perspective transformation between the staff gauge Region of Interest (ROI) and an orthographic template image. The measurement resolution of water level (1 mm) is controlled by the physical resolution (1 mm/pixel) of the template. The proposed water line detection approach is integrated by a series of algorithms: the Order-Statistic Filtering for adaptive thresholding, the Morphological Opening Operation for local noise suppression, the Multi-points Continuity Criterion for water line locating and the Median Filtering for random noise elimination. It overcomes the deficiency of traditional Otsu method for images with uneven illumination. The reliability of system under various weather and illumination conditions is proved with water level accuracy up to 1 cm and Effective Data Ratios up to 95%.     

TDICCD相机的低噪声视频处理技术

建立了TDICCD相机系统的噪声模型,分析了TDICCD视频信号读出复位噪声的产生机理,讨论了相关双采样技术的工作原理;给出了TDICCD相机视频处理电路各个组成部分的设计,并进行了分析。在此基础上设计了科学级TDICCD相机。实验结果表明,该视频处理电路在本身引入噪声较小的同时,有效地抑制了暗电流噪声、复位噪声、1／f噪声等,数据输出速率在55MHz时,整机信噪比（S／N）在50dB以上。     

面阵图像传感器在位移测量中的应用研究

在位移测量中,探索采用普通面阵ＣＣＤ取代线阵ＣＣＤ显得具有重大实用价值。本文将讨论微型ＣＭＯＳ电视摄像机作为图像卖座器在实时光电位移测量时的处理生能分析。理论和实际测试结果表明,在体积、成本、测量精度和抗干扰能力等方面,面阵图像传感器都优于线阵ＣＣＤ。     

Single-fluorophore imaging with an unmodified epifluorescence microscope and conventional video camera

Single fluorophores in aqueous solution were imaged in real time with a conventional silicon-intensified target video camera connected to an unmodified commercial microscope (IX70, Olympus) with epifluorescence excitation with a high-pressure mercury lamp. Neither a powerful laser nor an extremely sensitive video camera was required. Three experimental systems were used to demonstrate quantitatively that individual, moving or stationary Cy3 fluorophores could be imaged with the microscope: Cy3-gelsolin attached to an actin filament sliding over heavy meromyosin, sliding actin filaments sparsely labelled with Cy3, and heavy meromyosin labelled with one or two Cy3 fluorophores. The results should encourage many laboratories to attempt 'single-molecule physiology' in which the functions and mechanisms of molecular machines are studied at the single-molecule level in an environment where the biological machines are fully active.     

基于以太网的数字摄像机硬件接口设计

为实现数字化和网络化的视频监控,采用了专用音/视频压缩芯片和DSP芯片,及UDP数据报多播传输方式,完成了基于以太网的嵌入式数字摄像机的硬件接口设计及相应通信协议的设计,实现了全实时同步音/视频采集、压缩、存储和网络传输.研究结果表明,多媒体数据通信的实时性、连续性较好,并可实现多台计算机接收同一数字摄像机发出的图像、声音数据.     

基于相机溯源的潜在不良视频通话预警

目前主流的不良视频检测大多基于视频内容分析,属于计算密集型任务,不利于巨量视频通话流的实时检测。为此,本文试图从新的视角来阻断潜在不良视频的传播,即实时视频流相机溯源。和传统检测内容的方法不同,本文试图通过检测产生不良视频的相机源来阻断潜在不良视频的传播,即一旦发现某个正在视频通话的手机产生过不良视频,就发出安全警告进行阻断。该思路的基本假设是拍摄过不良视频的手机拥有者有更大概率利用同一部手机拍摄不良视频。该思路的核心问题是寻找一种实时、可靠的相机溯源方法。为此,本文主要聚焦以下三方面工作:建立了一个包含100部视频的数据库用于算法评估,数据库中的视频来自25部不同型号、不同品牌的相机,每一部视频注明了相机来源;建立了一种简单、有效的视频相机溯源机制,实现相机的在线实时溯源;提出了一种多相机指纹特征集成决策模型,实现可靠的相机溯源。实验结果显示,所提相机溯源机制能满足相机溯源的实时性要求,并且所提多相机指纹特征集成决策模型显著优于现有的单一模型,对于安卓手机,其视频相机溯源准确率达到98.161%,验证了该思路的可行性。     

Detection of kinematics parameters of index finger movement with high-speed video camera

Synergic movement of finger＇s joints provides human hand tremendous dexterities, and the detection of kinematics parameters is critical to describe and evaluate the kinesiology functions of the fingers. The present work is the attempt to investigate how the angular velocity and angular acceleration of the joints of index finger vary with respect to time during conducting a motor task. A high-speed video camera has been employed to visually record the movement of index finger, and miniaturized （5-mm diameter） reflective markers have affixed to the subject＇s index finger on the side close to thumb and dorsum of thumb at different joint landmarks. Captured images have been reviewed frame by frame to get the coordinate values of each joint, and the angular displacements, angular velocities and angular acceleration can be obtained with triangle function. The experiment results show that the methods here can detect the kinematics parameters of index finger joints during moving, and can be a valid route to study the motor function of index finger.     

The measurement of discharge using a commercial digital video camera in irrigation canals

This paper presents measurements of the discharge by image techniques on the surface velocity field and water stage in irrigation canals. The velocity and stage gauge are obtained from a commercial digital video camera. The time series of the surface velocity and stage were collected simultaneously. Particle image velocimetry (PIV) was used to determine the surface velocities in the irrigation canal. PIV proceeds by using bubbles floating on the water surface as tracer particles, and making a cross-correlation analysis between two continuous images. The whole surface velocity distribution in the irrigation canals can be obtained. The water stage of the canal is obtained from the digital video camera images by making use of image segments to separate the stage gauge and the background. The discharge is computed by using the surface velocities and water stage via open channel velocity distribution theory. Comparing the discharge measured using image techniques with Parshall flume data shows that the differences are less then 5%. The results suggest that the image measurement techniques developed can be used in applications to estimate the discharge in irrigation canals effectively.     

高速摄像技术在煤粉燃烧工作状态监控中的应用研究

针对高炉喷煤风口监控手段落后和回旋区耦合传热计算误差大、实时性差等问题，本文以高速摄像机作为测试工具，研究了喷煤高炉风口回旋区煤粉燃烧状态。用图像处理和三基色辐射测温法计算回旋区煤粉燃烧的温度变化和相对亮度变化，监控喷吹到高炉的煤粉粒子燃烧工况。并针对高速摄像机CCD传感器在高温测试过程中由于辐射强度过大易出现输出过饱和电流，导致“图像发白”问题，提出了摄像机快门控制模型，以提高摄像机测温动态范围，实现了风口回旋区温度和燃烧脉动的动态测量。通过现场应用表明，该方法为高炉喷煤提供了有力的测试手段和信息来源，快门控制模型提高了温度测量区间。     

Characterisation of a standard CCD video camera devoted to the design of an efficient particle image velocimetry instrument

A particle image velocimetry (PIV) instrument using a video frame grabbing system and two unsynchronised CCD video arrays was constructed. In the optical device, the two CCD are positioned at two perpendicular axes, with an image splitter located at their intersection and a single imaging lens in front of it. An optical characterisation of each CCD array and the imaging lens is needed to ensure that the field of view is similar for each vision system. Firstly, the experimental method of Cornu was used to deduce the basic optical parameters of the imaging lens. A simple video model was then performed to extract the unknown optical parameters of the device such as the angular field of view, the efficient dimensions of each CCD array and the transfer function from the CCD to the TV screen. An identification method based on global magnification measurements allowed the resolution of the micrometric stages needed for the spatial calibration step of the final instrument, to be deduced. Experimental tests have shown that the aberration in image formation was minimum with this configuration.     

绕光轴旋转拍摄LCD上平面靶标实现相机标定

针对在相机标定过程中传统的图像拍摄方法需要拍摄很多幅图像的问题,本文采用绕相机光轴旋转拍摄LCD屏幕上的平面靶标的方法,以利用少量图像获取较高的标定精度.通过对显示在LCD屏幕上的一个具有不同大小圆形特征点的标定表绕相机光轴旋转拍摄几幅图像,利用亚像素边缘轮廓检测算法检测图像中的轮廓,采用最小二乘椭圆拟合方法得到亚像素椭圆中心坐标,在Zhang的算法的基础上考虑切向畸变系数进行相机参数的计算,计算过程中对所求参数进行非线性优化.本方法利用LCD屏幕存在可视角度这一特性以及极高的几何精度和纯平面性的优点,与以往的拍摄标定方法相比较,本方法所需要图像幅数少,仅需3幅图像就可实现标定并得到较高的标定精度.实验表明,重投影平均误差在0.04个像素左右.证明了该标定方法的可行性和高的标定精度.     

计算机视觉中的摄像机标定方法

摄像机标定在三维重建、运动分析以及机器导航等领域中得到了广泛的研究和应用.根据标定技术特点,将摄像机标定分为两大类:基于标定物的摄像机标定和摄像机自标定,介绍了这两大类中典型的摄像机标定方法,回顾了其发展过程,并对各种方法的标定特点以及求解方法进行了分析,最后对摄像机标定方法的未来发展进行了展望.     

智能视频监控关键技术分析

智能视频监控是计算机视觉领域的一个重要的分支。智能视频监控系统中的相关关键技术引起广大学者关注,特别对于运动目标的跟踪和运动目标的检测问题,本文进行相关重点技术探讨,还包括智能视频监控系统中所处的重要位置,对于智能视频监控发展具有一定帮助作用。     

测绘相机的温度适应性

分析了温度对三线阵测绘相机传递函数和交会角的影响,通过热光学计算确定了测绘相机的热控指标.首先,在设定测绘相机热载荷状态的基础上,用有限元方法分析了温度场及热弹性变形;利用Zernike多项式进行波面拟合,代入光学软件考察温度对光学系统传递函数的影响,得到测绘相机光学传递函数在假定温度场作用下的下降系数.然后,进行了测绘基座的热尺寸稳定性分析.并在此基础上考察了温度对测绘相机交会角的影响.实验显示,上述分析避免了热控设计的过设计或设计不足,为制定合理的热控设计指标提供了数据依据.     

单目OV6620数字摄像头在视觉测距中的应用

单目摄像测距系统在对固定目标的测距中具有精确、灵敏的特点。介绍了使用OV6620数字摄像头借助激光三角测距法实现对目标物的测距原理及实现过程。通过试验证明,该系统在一定条件下可实现有效测距。