Novel nonlinear filter for noise suppressing of interferometric SAR

The nonlinear filter is an important method for phase image noise reducing of interferometric SAR. The modified median filter and the modified mode filter are the main nonlinear filters to reduce the noise of interferometric phase image. They can suppress the noise well, but blur the image edge. The neighbour average is a kind of noise suppressing methods which keep the image edge well. Based on the neighbour average method, a novel nonlinear filter was presented to suppress the phase noise of interferometric SAR and it was referred as the modified neighbour average filter which can keep the image edge well. Combining the phase image characteristics of interferometric SAR, the new formula to calculate the average value was presented and some rules were applied to limit the filtering. The modified neighbour average filter was compared with the modified median filter and the modified mode filter. With the Residual point concept, one method was given to evaluate the phase noise suppressing methods. Finally, ERS1/2 interferometric data was processed with the three nonlinear filters and the results were employed to illustrate the correction of the analysis of this paper.