ESPI Image Denoising and Edge Extraction Based on Wavelet Transform

The high noise of ESPI(Electronic Speckle Pattern Interferometry) fringe pattern leads to the low ratio of signal-to-noise,there are some drawbacks of common image filtering method used in the speckle interferometry fringe pattern.According to the characteristics of speckle fringe pattern,the iterative filtering method based on adaptive filter and wavelet transform was established.On the basis of speckle fringe image pretreatment,the different wavelet functions,decomposition levels and threshold were chosen to achieve the different filtering effect.The repeated experiments proved that the iterative filter effect is the best when the threshold is 0.15~0.3 and wavelet function with the 4 layer decomposition,and then the image binarization and edge detection was carried out using Sobel operator,finally the marginal distribution of ESPI fringe pattern was obtained.The experiment results indicate that the method is able to achieve a good effect in the respect of speckle noise removal and edge preservation during the process.