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Proceedings Paper

Speckle reduction for SAR images using edge directions in wavelet domain
Author(s): Xiaowei Guo; Zheng Tian
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Paper Abstract

A filter for speckle reduction in SAT image is proposed. On each level of wavelet decomposition, three images are used. One is the original image, and the others are obtained by rotating the original image by 45° and -45° respectively, and so 12 subbands are gotten. In the 12 subbands, four subbands, HL subband and LH subband corresponding to the original image, and two HL subbands corresponding to the second and third image respectively, are used for edge detection, and the LL, HL, LH, HH subbands of the original image are used for synthesis. By using each point's four wavelet coefficients in the four subbands for edge detection, the edge detection property of the point on the original image is captured, and then the edges are detected by setting a proper threshold. And so, the speckle can be reduced while the edges being preserved well by setting the wavelet coefficeints in the synthesis subbands corresponding to the points not on edges to zero but retain the wavelet coefficients in the synthesis subbands corresponding to the points on edges. For detection of some oscillating edges, the filter is improved by combining with the traditional threshold method. Simulations on synthetic images indicate that the new filter performs better than the traditional wavelet domain hard threshold or soft threshold method.

Paper Details

Date Published: 25 September 2003
PDF: 5 pages
Proc. SPIE 5286, Third International Symposium on Multispectral Image Processing and Pattern Recognition, (25 September 2003); doi: 10.1117/12.538795
Show Author Affiliations
Xiaowei Guo, Northwestern Polytechnic Univ. (China)
Zheng Tian, Northwestern Polytechnic Univ. (China)


Published in SPIE Proceedings Vol. 5286:
Third International Symposium on Multispectral Image Processing and Pattern Recognition
Hanqing Lu; Tianxu Zhang, Editor(s)

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