High-resolution No.3 SAR image speckle reduction method based on improved Frost filtering and shear waves

Abstract

The invention belongs to the technical field of image processing, and particularly relates to a high-resolution No.3 SAR image speckle reduction method based on improved Frost filtering and shear waves. The high-resolution No.3 SAR image speckle reduction method comprises the following steps: S1, converting an SAR image noise model; S2, carrying out shear wave transformation; S3, processing the high-frequency coefficient by using a Frost filtering algorithm of L1 / 2 norm; S4, carrying out shear wave reconstruction; and S5, performing exponential transformation on the reconstructed image. The high-resolution No.3 SAR image speckle reduction method filters the SAR image by using the shear wave with the optimal sparsity, utilizes the good directivity of the shear waves, and effectively reserves the edge detail part of the image while filtering spots, and processes the high-frequency coefficient after shear wave transformation based on improved Frost filtering, so that the effect of filtering spots is effectively achieved, and information such as edge details of the image is efficiently reserved.

Description

technical field [0001] The invention belongs to the technical field of image processing, and in particular relates to a speckle reduction method for Gaofen-3 SAR images based on improved Frost filtering and shear waves. Background technique [0002] GF-3 is the synthetic aperture radar (SAR) satellite with the most imaging modes in the world, with 12 imaging modes. It can simultaneously transmit and receive horizontal waves and vertical waves, and is my country's first multi-polarization SAR satellite. The Gaofen-3 satellite has been put into use, filling the blank of civil high-resolution synthetic aperture radar satellites, marking the initial formation of Gaofen's special all-weather and all-weather earth observation capabilities, which will serve economic and social development and ensure national security and people's livelihood security. is of great significance. However, due to the coherent imaging mechanism, the GF-3 SAR image will also produce bright and dark spot...

AI Technical Summary

Problems solved by technology

However, due to the coherent imaging mechanism, the GF-3 SAR image will also produce bright and dark spots, which seriously affects the interpretation of the image. Therefore, it is particularly important to be able to effectively filter out the image spots and at the same time retain the edge information.

[0003] Due to the multiple imaging modes and high resolution of the Gaofen-3 satellite, the edge, point, texture and other information of the Gaofen-3 SAR image formed are extremely obvious. The traditional Frost filter algorithm uses Gaussian weighted L 2 norm, while L 2 The norm does not have good sparsity. While filtering out speckles, it cannot preserve details such as the edges of the image very well. It is not suitable for processing Gaofen-3 SAR images.

[0004] Shear wave has the best sparse representation and the most complete mathematical theory, so the shear wave is used to deal with the speckle reduction of the Gaofen-3 SAR image. For example, the application number 201711221301.7 adopts the shear wave processing, which affects the high frequency coefficient ( The noise part exists in the high-frequency coefficient) is processed by wavelet hard threshold value, although the effect of image speckles is filtered to a certain extent, but the effect is not particularly ideal

Images