Image enhancement for the phase stepped interferometric process by appropriate filtering

PSI (Phase Stepped Interferometry) is a well known technique for the measurement of surface deformation. Since in this technique phase characteristic of a linear system is computed using arctangent function, in some points the raw phase data exceeds the value 2π. Moreover the surface roughness, phase unwrapping and extra noise imposed from the environment makes the surface look like a original surface with huge impulsive noise and simply using PSI technique does not produce accurate reconstructed surface. In this paper we propose a filtering technique that suppress the noise and enhance the image quality. We propose that the raw phase data should be prefiltered by a mean filter to eliminate Gaussian noise. Then after proper unwrapping treatment the data should be filtered with a RCM (Rank Conditioned Median) filter. This filter is effective at treating impulsive type noise and preserve step edges without blurring