Sar image speckle reduction method based on sketch map and kernel selection

Abstract

The invention discloses an SAR image speckle reduction method based on a sketch and kernel selection. The method mainly solves the problem that the correlation of pixels in image blocks is not considered in the process of calculating the similarity of the pixels by using the image blocks when speckles of an SAR image are restrained in the prior art. The method includes the following steps: extracting the sketch of the SAR image by using multi-scale and multi-direction ratio operators, dividing the SAR image into a structural region and a non-structural region according to the extracted sketch, constructing a kernel mapping function with directional characteristics and anisotropism by using geometric structure characteristics of the divided regions, searching the local maximum homogenous region for each pixel through block similarity measure by using the constructed kernel mapping function, and achieving restraint on the speckles of the whole SAR image by regarding the maximum likelihood value of the homogenous region as the value of the current pixel. The SAR image speckle reduction method based on the sketch and kernel selection enhances the effect of restraining the speckles of the SAR image and can be applied to SAR image denoising.

Description

technical field [0001] The invention belongs to the technical field of image processing, relates to a SAR image coherent speckle suppression method, and can be used for SAR image coherent speckle suppression. Background technique [0002] The SAR image is formed when the electromagnetic wave emitted by the synthetic aperture radar meets the scattering source for backscattering. Therefore, the imaging process is often accompanied by the coherence phenomenon between the backscattered electromagnetic waves. This makes speckle information formed due to coherence always appear in SAR images, which is called coherence speckle. To a certain extent, these coherent speckle information cause great difficulties to the understanding and interpretation of SAR images. By suppressing the coherent speckle in SAR image, it is beneficial to the understanding and interpretation of SAR image. Therefore, the speckle suppression operation is one of the key technologies in the subsequent process...

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to use the geometric characteristics in the local block of the image, that is, the correlation characteristics between the pixels in the block to select and construct the kernel function in the similarity measure, because the kernel function in the similarity measure of the current image block cannot fully reflect the pixels of the image block In order to improve the estimation accuracy of SAR image signals and achieve effective suppression of speckle noise

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