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SAR (Synthetic Aperture Radar) image speckle reduction method based on sparse representation

A technology of coherent speckle suppression and sparse representation, applied in the field of image processing, can solve problems such as blurred edges, loss of image details, serious problems, etc., and achieve the effect of ensuring integrity and noise suppression

Active Publication Date: 2012-02-08
XIDIAN UNIV
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Problems solved by technology

S.Foucher made a preliminary attempt to suppress SAR coherent speckle by using sparse redundant representation. He reconstructed the logarithmically transformed image by modifying the objective function, but the details of the processed image were seriously lost, and certain edges appeared. Vague

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  • SAR (Synthetic Aperture Radar) image speckle reduction method based on sparse representation
  • SAR (Synthetic Aperture Radar) image speckle reduction method based on sparse representation
  • SAR (Synthetic Aperture Radar) image speckle reduction method based on sparse representation

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Embodiment Construction

[0033] Reference figure 1 The specific implementation process of the present invention is as follows:

[0034] Step 1. Input the SAR image Y to be subjected to coherent speckle suppression, and perform logarithmic operations on it to obtain the logarithmic transformed image Y'.

[0035] Step 2. Divide the logarithmic transformed image Y′ into size Overlapping blocks.

[0036] Choose the size of n as 64, that is, divide the image into overlapping blocks of size 8×8, and extract the image blocks of size 8×8 to the right and down respectively with each pixel in the image as the starting point, and use The coordinates of the starting pixel point are used to mark the position of the block in the original image. The size of the SAR image used in the experiment is 256×256, and the number of image blocks after segmentation is (256-7)×(256-7)=249 2 = 62001.

[0037] Step 3. Perform sparse coding on each overlapping block after segmentation, and introduce its own pixel information of the ima...

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Abstract

The invention discloses an SAR (Synthetic Aperture Radar) image speckle reduction method based on sparse representation, which mainly solves the problems of incomplete detail information and unsmooth homogeneous regions for SAR image speckle reduction in the prior art. The method comprises the following steps of: carrying out logarithmic transformation on an original SAR image Y; carrying out overlapping blocking on an image Y' subjected to logarithmic transformation; taking the own information of the image blocks as control factors and carrying out sparse representation on the control factors; carrying out dictionary learning by adopting an approximate KSVD (K Singular Value Decomposition) algorithm to obtain a self-adaptive dictionary and updated sparse representation coefficients; obtaining an image W by adopting the self-adaptive dictionary and the updated sparse representation coefficients, and carrying out exponential transformation on the image W to obtain an image R; and carrying out nonlinear anisotropic diffusion on a difference image V obtained from the original SAR image Y and the image R subjected to the exponential transformation, thereby obtaining a final speckle-reduced image. The method disclosed by the invention has the advantages that the homogeneous regions of speckle reduction results are smooth, point targets are clear and visible, and edge information iskept complete and the like, besides, the method is suitable for a preprocessing process of SAR image understanding.

Description

Technical field [0001] The invention belongs to the technical field of image processing, and relates to a method for suppressing coherent speckles of SAR images, which can be used for SAR image scene analysis and image understanding preprocessing. Background technique [0002] Synthetic Aperture Radar SAR has a wide range of applications in military and civilian fields because of its all-weather, all-weather imaging and strong penetrability. In the SAR imaging process, due to the influence of the fading effect produced by the coherent effect of electromagnetic waves, random distribution of speckle noise, that is, coherent speckle, is generated in the image. The existence of coherence spots seriously affects the understanding and automatic interpretation of images, and reduces the effectiveness of image segmentation and target recognition and extraction. Therefore, performing coherent speckle suppression on SAR images is a necessary prerequisite for other operations. [0003] One ...

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Application Information

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IPC IPC(8): G06T5/00G06T5/50G06T7/00
Inventor 侯彪焦李成蒋继光王爽刘芳尚荣华
Owner XIDIAN UNIV
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