Image denoising in security inspection of pantograph catenary

In the monitering of pantogragh-catenary system by the real-time methods, image processing technology is very important .As the first step of this technology, the image preprocessing is also crucial important. It is directly related to the precision of image processing during the following steps, then affecting the accuracy of testing results. Therefore, this paper discusses four algorithms of DCT, DWT, PCA, SVD ,for the unstable system like the pantograph and catenary system, this paper discuss the performance of these four methods. The comparasion results of image processing are obtained by Matlab programming. Finally, using the gray value and the signal-to-noise ratio to test the results, then the optimal image denoising algorithm of pantograph system is obtained. This optimal algorithm can provide the reference for engineering practice.