A method consisting of the median filtering and the differential Fourier analysis is proposed to analyze the speckle correlation fringes. In the method, these two operations act effectively as a band-pass filter since the speckle noise with high frequencies is suppressed by the median filtering and the pedestal variation with low frequency is removed through the differentiation of fringe signals. In computer simulations, the performance of the method is compared with that based on the ordinary Fourier analysis and examined with respect to the window size of median filters used. It is revealed that speckled fringes with the low visibility can be successfully analyzed with high accuracy. The validity of the method is also experimentally shown by applying it to the analysis of speckle correlation fringes obtained in speckle photography.
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