Method for inhibiting speckle noise of polarized SAR (Search and Rescue) data

Abstract

The invention discloses a method for inhibiting speckle noise of polarized SAR (Search and Rescue) data, which mainly solves the defects that the traditional method for inhibiting speckle noise of polarized SAR data can not inhibit speckle noise very well and loses part of edges and detailed information. The method for inhibiting speckle noise of polarized SAR data combines the ideas of improving sigma filtering and non-local mean values and comprises the following steps of: (1) inputting a coherence matrix T of polarized SAR data; (2) detecting a light target of the coherence matrix T; (3) judging the direction of a pixel by using a direction window and carrying out improved sigma filtering and the non-local mean-value filtering; (4) combining filtering results and retaining the light target; and (5) completing the filtering of the coherence matrix T and combining a pseudo color. Compared with the prior art, the invention obviously increases the speckle noise inhibiting ability of the polarized SAR data, can effectively smooth a homogeneous region and retain the edge detailed information and can be used for a pretreatment process of the polarized SAR data.

Description

technical field [0001] The invention belongs to the technical field of image data processing, in particular to a method for suppressing coherent spots, which can be used for denoising SAR images and polarimetric SAR data. Background technique [0002] With the development of radar technology, polarization SAR has become the development trend of SAR. Polarization SAR can obtain more abundant target information, which is conducive to improving target detection, identification and classification capabilities, etc., which reflects the advantages of polarization SAR system. , but like SAR, it is severely disturbed by coherent speckle noise. Therefore, the suppression of coherence speckle is known as an enduring research topic. For polarimetric SAR data, the purpose of speckle suppression is to suppress coherent speckle while maintaining the polarization characteristics, edge details and texture information of the data. There are many existing methods for speckle suppression of ...

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Problems solved by technology

[0003] 1) Polarization whitening filter PWF is the earliest filtering method. This method completes the coherent speckle suppression of span data by optimizing the combination of polarization SAR data scattering matrix elements, but the disadvantage of this method is that it only affects the polarization SAR The span data in the data is subject to coherent speckle suppression, while the elements of the other polarimetric SAR data are not subject to coherent speckle suppression

[0004] 2) The most classic method is refined polarized Lee filtering, which uses edge windows for filtering. The filtered data has a significant effect in maintaining the characteristics of the edge. However, the filtering effect is not particularly ideal in maintaining texture detail information. Therefore, in the suppression of coherent speckles, some original characteristics of the data cannot be well preserved

[0005] 3) The newly proposed improved sigma filter solves the shortcomings of the original sigma filter that the dark pixels are not filtered and there are errors in the filtered data, and effectively maintains the bright target pixel. The smoothness of the homogeneous area is better than that of the refined polarization Lee filtering method, but on the edge, due to the influence of coherent spots, some "burrs" will appear in the filtered data, and the smoothness of the homogeneous area has not yet reached the best

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