A new fringe-pattern preprocess method based on median spin filtering

A new fringe-pattern preprocess based on median spin filter is proposed to deal with the interferogram with high-level noises. It only smoothes noises in fringe-tangential direction by median filter, therefore, it can filter off noises such as coherent artifacts, additive random noise, “Salt and pepper” and large bright and black spots, without blurring and distorting the fringe-pattern features. The experimental results show that the median spin filter is suitable for the interferogram with all kinds of noise, especially the random noise, speckle noise and large bright or black spots. The method is better than Gerchberg's extrapolation algorithm and filters in frequency space when dealing with large bright or black spots. The P-V and RMS errors are less than 1.5% and 2.3% for 95% apertu