Edge and fine detail preservation in SAR images through speckle reduction with an adaptive mean filter

A speckle reduction algorithm, the Edge Map‐Directed Adaptive Mean (EMDAM) filter, is studied in this paper. It adapts the ordinary mean filter according to the scene heterogeneity. Edge‐crossing maps determined by an edge detector are used to find the largest homogeneous subregion in the moving filter window. Then, the mean filter is adapted only to this homogeneous part of the moving filter window and applied if no edge crossing is found. We compared some filters in the literature to the EMDAM filter using two examples: a 1997 JERS‐1 synthetic aperture radar (SAR) image of Tuzla, Istanbul and a computer‐simulated SAR image. The filter performance was assessed both quantitatively and qualitatively. We found that the EMDAM filter preserves textures and details while reducing speckle to a desired level. A new testing quantity, the Quality Factor (Q), is also introduced.

[1]  Victor S. Frost,et al.  A Model for Radar Images and Its Application to Adaptive Digital Filtering of Multiplicative Noise , 1982, IEEE Transactions on Pattern Analysis and Machine Intelligence.

[2]  Ridha Touzi,et al.  A review of speckle filtering in the context of estimation theory , 2002, IEEE Trans. Geosci. Remote. Sens..

[3]  E. Nezry,et al.  Structure detection and statistical adaptive speckle filtering in SAR images , 1993 .

[4]  A. Lopes,et al.  A statistical and geometrical edge detector for SAR images , 1988 .

[5]  Philippe Bolon,et al.  Statistical and operational performance assessment of multitemporal SAR image filtering , 2003, IEEE Trans. Geosci. Remote. Sens..

[6]  M. Nagao,et al.  Edge preserving smoothing , 1979 .

[7]  Jong-Sen Lee,et al.  Refined filtering of image noise using local statistics , 1981 .

[8]  E. Nezry,et al.  Adaptive speckle filters and scene heterogeneity , 1990 .

[9]  Yunhan Dong,et al.  Toward edge sharpening: a SAR speckle filtering algorithm , 2001, IEEE Trans. Geosci. Remote. Sens..

[10]  J. Goodman.  Some fundamental properties of speckle , 1976 .

[11]  F. J. Martin,et al.  SAR speckle reduction by weighted filtering , 1993 .

[12]  Jong-Sen Lee,et al.  A simple speckle smoothing algorithm for synthetic aperture radar images , 1983, IEEE Transactions on Systems, Man, and Cybernetics.

[13]  Thomas R. Crimmins.  Geometric Filter For Reducing Speckle , 1986 .

[14]  Alexander A. Sawchuk,et al.  Adaptive restoration of images with speckle , 1987, IEEE Trans. Acoust. Speech Signal Process..

[15]  F. Tupin,et al.  Smoothing speckled SAR images by using maximum homogeneous region filters: an improved approach , 2001, IGARSS 2001. Scanning the Present and Resolving the Future. Proceedings. IEEE 2001 International Geoscience and Remote Sensing Symposium (Cat. No.01CH37217).

[16]  Henri Maitre,et al.  Smoothing speckled synthetic aperture radar images by using maximum homgeneous region filters , 1992 .

[17]  Jong-Sen Lee.  Speckle suppression and analysis for synthetic aperture radar images , 1986 .

[18]  M. Sties,et al.  Efficient speckle filtering of SAR images , 1994, Proceedings of IGARSS '94 - 1994 IEEE International Geoscience and Remote Sensing Symposium.

[19]  S. Quegan,et al.  Understanding Synthetic Aperture Radar Images , 1998 .