Electronic speckle interferometry image processing based on homomorphic filtering

More attention was paid to research of speckles because of their measurable intensity and certain phase.Now speckles are used extensively in the field of non-destructive test.The electronic speckle pattern interferometry (ESPI) is always full of a lot of noise.Generally,the information about deformation recorded by the fringe is mainly distributed in the low frequency domain,whereas the noise is in the high frequency part.In order to obtain the continuous phase distribution of the deformed object,it is necessary to take some proper methods to remove the noise in the fringe.Homomorphic filtering is a frequency domain operation to compress image intensity area and enhance contrast.A new filter based on the principle of homomorphic filtering was designed,which was used for three-step phase-shifting electronic speckle image processing.A theoretical analysis was also proposed in detail.The experimental results show that the speckle noise was removed to the large extent and the contrast of ESPI fringes can be increased by the proposed method.