SAR (synthetic aperture radar) image despeckle method based on target extraction and three-dimensional block matching denoising

Abstract

The invention discloses an SAR (synthetic aperture radar) despeckle method based on target extraction and three-dimensional block matching denoising, and mainly solves the problem that despeckle effect and detail keeping cannot be considered at one time in the prior art. The implementation steps of the method include: firstly, extracting and removing a target image of an input SAR image; secondly, calculating an iterative initial value, and setting iterative times and iterative step size; thirdly, performing logarithmic transformation to an image after the target image is removed, denoising by the three-dimensional matching denoising algorithm with different standard deviations of noise, and selecting the best noise deviation by evaluating the edge preserving capacity and equivalent number of looks of the denoised image; fourthly, performing three-dimensional matching denoising to a logarithmic image by the best standard deviation of the image; and fifthly, performing exponent transformation to the denoised image, and adding the image with the target image to acquire a final despeckled image. The method has the advantage that image details are saved well, is effective in despeckle, and can be used for SAR image target identification and target detection.

Description

technical field [0001] The invention belongs to the technical field of image processing, in particular to a speckle removal method, which can be applied to target recognition and target detection in SAR images. Background technique [0002] Synthetic Aperture Radar, or SAR for short, is an all-weather, all-weather radar that can obtain high-resolution images similar to optical images under various weather conditions, and belongs to the active remote sensing system. SAR is not affected by conditions such as light and weather, and can be used in many fields such as agriculture, military, navigation, and geographical surveillance. However, due to the fading effect caused by coherent illumination in the process of SAR imaging, the homogeneous area in the image that originally has the same backscattering coefficient shows granular noise, which is called coherent speckle. The existence of speckle increases the complexity of image interpretation and greatly reduces the effectivene...

AI Technical Summary

Problems solved by technology

However, when it is used in SAR image despeckling, because the existing noise estimation techniques have certain errors, it is impossible to accurately know the noise standard deviation of SAR image, so the best despeckling effect cannot be obtained, and some loss of image information

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