Despeckling of SAR Images by Finding the Expected Values Using the Probability Distribution of Speckle
Synthetic aperture radar (SAR) images are contaminated by multiplicative speckle noise, which reduces the contrast and resolution of the images. To improve the quality and the performance of quantitative image analysis, speckle reduction is a prerequisite for SAR images. In this paper, a new method is proposed by calculating the expected value of all the pixel elements in the window with respect to the centre pixel. The weighted mean of all the expected values in the window replaces the centre pixel. The weights are calculated according to the height of the probability distribution. Thus, the expected value which has higher probability has more weightage. The proposed method is applied to the air-borne and space-borne SAR images. By comparing with some well-known filters, the obtained results demonstrate that the proposed method is able to reduce the noise effectively with accurately preserving edges and fine details of the images.
KeywordsSAR image Speckle noise Speckle filter Image filter
- Buades A, Coll B, Morel J-M (2005) A non-local algorithm for image denoising. In: Computer vision and pattern recognition, CVPR 2005. IEEE Computer Society Conference, vol 2, pp 60–65Google Scholar
- Lopes A, Nezry E, Touzi R, Laur H (1990a) Maximum a posteriori speckle filtering and first order texture models in SAR images. In: Geoscience and remote sensing symposium, 1990. IGARSS’90.’ remote sensing science for the nineties’, 10th annual international, pp 2409–2412Google Scholar
- Novak LM, Burl MC (1990) Optimal speckle reduction in polarimetric SAR imagery. IEEE Trans Geosci Remote Sens 26(2):293–305Google Scholar
- Pratt WK (1975) Median filtering. Image Process Inst Univ Southern California Los AngelesGoogle Scholar
- Yamamoto K, Yamaguchi Y, Park S-E, Cui Y, Yamada H (2013) Comparison of speckle filtering methods for POLSAR analysis of earthquake damaged areas. In: Synthetic aperture radar (APSAR), 2013 Asia-Pacific conference on IEEE, pp 358–360Google Scholar