【作者】 汪旋；

【导师】 高晓东；

【作者基本信息】 中国科学院研究生院（光电技术研究所） ， 测试计量技术及仪器， 2014， 博士

【摘要】 数字航空相机出厂前，需要将CCD安装在相机物镜焦面处，但是在空中执行任务时，由于温度、压力等环境因素的影响，物镜的焦面会发生移动，当移动量超出半焦深时，拍摄的图像会变得模糊不清，最终导致任务失败。为了避免失败的发生，航空相机需要具备自动检调焦能力，国内外航空相机主要采用的检调焦方式有程序控制法、图像处理法和光电自准直法。本文在详细分析各种常用方法优缺点的基础上，结合数字航空相机成像的特点，提出了一种基于图像处理的光电自准直检调焦方案，并对相关理论进行了深入研究。根据图像模糊理论，清晰图像比被模糊的图像有更丰富的细节信息，即高频分量，所以可以通过衡量图像包含高频信息的多少来判断图像离焦与否，基于图像处理的自动调焦技术应运而生。本文阐述了图像评价函数应具备的特点，并对现有图像预处理理论进行详细分析，而后，利用matlab分别对空间域、频率、信息学和图像熵中的经典图像评价函数进行了仿真，结果表明：对于光栅图像序列，能量梯度函数具有显著优势。结合光栅图像特有的性质，提出了4种基于线阵CCD检调焦的方法，分析比较了各自的优缺点。窗口选择直接影响到调焦过程的复杂度、计算量和精确度，本文结合光栅调焦的特点，通过比较窗口大小对评价函数特性的影响，提出基于中心的40×32窗口满足系统要求。聚焦策略对于自动调焦系统而言同样至关重要，本文在详细分析现有搜索算法的特点的基础上，提出8点4阶曲线拟合和改进爬山相结合的算法，分别在良好情况和恶劣情况下进行动态调焦实验，获得了良好的实验结果。理论需要实验来支撑，本文利用光机电算的知识，基于科勒原理设计均匀照明系统，在对调焦组件的设计中，对步进电机速度控制进行了研究，并基于DSP2812实现了的步进电机速度控制。在对上位机总控系统的设计中，对基于MFC多线程设计进行了研究。误差是不可避免的，本文在对实验相关数据分析之后，对高度和斜视离焦进行了详细分析，并创新性的对CCD和光栅的安装位置进行了研究，研究发现，位置安装误差线性的影响调焦精度，进一步提出了特种目标的方法。理论应用于实际是需要变通的，本文的最后为全文研究的理论给出了几种新的应用形式，大大的拓展了应用范围。本文针对利用光栅图像处理的方法实现数字航空相机自动调焦的问题，进行了深入的理论和应用研究，为相机在轨调焦提供了方法依据。更多还原

【Abstract】 Before digital aerial camera working, the CCD needs to be installed in the focalplane. Due to the influence of temperature, pressure and other environmental factors,the focal plane may occur to move in task.When the amount of movement exceedshalf of the focusing depth, the captured image will become blurred, resulting inmission failure. In order to avoid the occurrence of failure, aviation inspection cameraneeds the capability of auto focusing. The cameras always focus with ways asprogram camera control method, image processing method and photoelectricautocollimator law. Based on the detailed analysis of the advantages anddisadvantages of various commonly used methods with the combination of digitalaerial camera imaging features, a new optical image processing based on self-collimation inspection program focusing is prepared, and the theory is conductedin-depth.According to the image fuzzy theory, clear images can be richer in details thanthe blurred image, namely the high-frequency components. So the image can bejudged whether defocus or not by measuring how much high frequency informationthe image contains, the focusing method based on image processing technologycomes into being. This paper describes the characteristics of the image evaluationfunction and studies the image pre-existing theory, and then, simulate classic imageevaluation function using matlab respectively spatial domain, frequency, informaticsand image entropy. Results show that: For the raster image sequence, the energygradient function has a significant advantage. Combined with the unique nature ofraster images, four kinds of linear CCD based approach focusing inspection arepresented, also, analyse and compare their advantages and disadvantages.The selection process of focusing window affects the complexity and accuracyof computation directly. Characteristics of this paper focusing grating, window sizeby comparing the impact properties of the evaluation function is proposed to meetthe system requirements are based on the center of the window40×32. FocusStrategies is also essential for automatic focusing system, this paper proposed8point4orders scurve fitting algorithm by analyzing the characteristics of the existingsearch algorithms in detail, and get a good result in dynamic focusing with in goodconditions and bad conditions experiment. The theory needs to be supported by experiments, based on the principles ofKohler, we design uniform illumination system using electromechanical operatorknowledge. The stepper motor speed control was studied on the design of focusingcomponents, and achieves a stepper motor speed control based on DSP2812. The hostcomputer system design were studied based on MFC multithreaded design.Error is inevitable, after analyzing the experimental data, the paper, thetheoretical derivation of the formula for the depth of focus on the height andstrabismus defocus analyzed in detail, and innovative mounting position of CCD andgrating were studied, the study found the impact location of the installation errorlinear focusing accuracy, the method further proposed focusing special goal.Theory needs the modifications in order to be applied to the actual.the papergives several new application forms by using the new ways at last, which greatlyexpands the range of applications.In this paper, we study in depth of the automatic focusing problems by rasterimage and the applied research. The camera provides a method for in-orbitfocusing.更多还原