The Design Of Preprocessing System Besed On Area Array CCD For Railway Image Detection

With the rapid development of China’s high-speed rail and the advancement of urban subway transportation,people have paid more and more attention to the safety of transportation facilities,especially the detection of vulnerable railway tracks exposed to nature.The non contact method of acquiring railway images and then detecting them by algorithms has the advantages of low cost,high accuracy,and fast speed.This method has received more and more attention.Aiming at the problems of the current track detection system,this paper designs a real-time railway image preprocessing system based on the FPGA platform.Two improved image preprocessing methods are proposed,and the algorithm is transplanted to the FPGA using a hardware programming language to implement the preprocessing algorithm real-time processing.In terms of hardware design,based on the structure of the image preprocessing hardware system,the system hardware platform with area array CCD as the imaging sensor is designed.The area array CCD drive timing analysis and the design of the drive circuit are introduced.This paper make full use of the characteristics of FPGA parallel operation,realize the pipeline processing structure of pixels,and achieve the hardware implementation of image preprocessing algorithm.According to the characteristics of railway images in software simulation,in-depth research is performed on adaptive median filtering and Laplace enhancement in image preprocessing.The improved adaptive median filtering method and threshold-enhanced image enhancement method are proposed.Through simulation and comparison,the method in this paper has better denoising and enhancement effects than traditional method.Finally,the whole preprocessing system is tested experimentally.This paper uses an oscilloscope to measure whether the waveform of the area array CCD drive board is correct,and the LCD display is driven to obtain a good imaging effect after the CCD signal is collected and processed;The FPGA test platform is used to run the improved algorithm,and the pre-processed results are evaluated in two parameters,PSNR and NMSE,and the processing speed of the system was tested.The test results verify the correctness,effectiveness and real-time performance of the preprocessing algorithms.The whole worklays the foundation for further railway detection.