Scale-space filter for smoothing electronic speckle pattern interferometry fringes

Processing of correlation fringes obtained from electronic speckle pattern interferometry (ESPI) requires the use of a digital filter to reduce the speckle noise. Even though smoothing algorithms based on the Fourier transform significantly suppress speckle noise, they do not preserve the image characteristics. The application of a scale-space filter to reduce speckle noise in ESPI fringes is reported. Results obtained using both computer-simulated and experimental fringe patterns are used to test the scale-space filter and they are also compared with those obtained by Fourier, convolution, and median filtering. (C) 1996 Society of Photo-Optical Instrumentation Engineers.