Paper
25 September 2003 Speckle reduction for SAR images using edge directions in wavelet domain
Xiaowei Guo, Zheng Tian
Author Affiliations +
Proceedings Volume 5286, Third International Symposium on Multispectral Image Processing and Pattern Recognition; (2003) https://doi.org/10.1117/12.538795
Event: Third International Symposium on Multispectral Image Processing and Pattern Recognition, 2003, Beijing, China
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.
© (2003) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Xiaowei Guo and Zheng Tian "Speckle reduction for SAR images using edge directions in wavelet domain", Proc. SPIE 5286, Third International Symposium on Multispectral Image Processing and Pattern Recognition, (25 September 2003); https://doi.org/10.1117/12.538795
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KEYWORDS
Wavelets

Synthetic aperture radar

Edge detection

Speckle

Discrete wavelet transforms

Image filtering

Image processing

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