Auto-focusing Technique For Aerial Camera Base On Image Processing

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.