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SAR image registration method based on SIFT and normalized mutual information

An image registration and mutual information technology, applied in the fields of image navigation and image processing.

Active Publication Date: 2014-06-04
XIDIAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

First of all, due to the influence of coherent speckle noise in SAR images, it is likely to detect noise points as feature points, which will lead to wrong registration results; secondly, airborne SAR images may be disturbed by actual conditions, and the brightness and contrast may be relatively dark, which cannot Match the SAR images directly, otherwise, the correct matching point pairs cannot be obtained; finally, after the initial matching, mis-matching is inevitable, which has a great impact on the registration results

Method used

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  • SAR image registration method based on SIFT and normalized mutual information

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Embodiment 1

[0129] The present invention proposes a SAR image registration method based on SIFT and normalized mutual information. The simulation of this example is a CPU intel Pentium Dual-Core E5300 with a main frequency of 2.60GHz, a hardware environment with 2GB of internal memory and the software of MATLAB R2011a The environment is carried out under the Windows XP SP3 system.

[0130] The present invention proposes a SAR image registration method based on SIFT and normalized mutual information to improve the accuracy and robustness of SAR image registration and realize SAR image registration, such as figure 1 As shown, the present invention realizes that the SAR image registration process includes the following steps:

[0131] Step 1: Input two SAR images, one of which is the reference image I 1 , and the other is the image to be registered I 2 , respectively preprocess the two SAR images, first adopt Rayleigh distribution, the enhancement coefficient is 0.2 for the two SAR images ...

Embodiment 2

[0138] The SAR image registration method based on SIFT and normalized mutual information is the same as embodiment 1. In order to have practicability, the present invention is further described in detail as follows:

[0139] The concrete process that the MM-SIFT method described in step 2 carries out feature extraction includes as follows:

[0140] 2.1 Gaussian Blur and Scale Space Generation

[0141] For a two-dimensional image I(x,y), the scale space L(x,y,σ) at different scales can be obtained by convolution of the image I(x,y) with the Gaussian kernel G(x,y,σ):

[0142] L(x,y,σ)=G(x,y,σ)*I(x,y)

[0143] in, (x,y) represents a point on I, and σ is a scaling factor. The construction process of the Gaussian pyramid can be divided into two steps: (1) Gaussian smoothing of the image; (2) downsampling of the image;

[0144] In order to make the scale reflect its continuity, Gaussian filtering is added on the basis of simple downsampling. One image can generate several group...

Embodiment 3

[0234] The SAR image registration method based on SIFT and normalized mutual information is the same as in Embodiment 1-2, and the SAR image registration effect of the present invention can be further illustrated by the following experiments:

[0235] The simulation experiment environment is: MATLAB R2011a, CPU intel Pentium Dual-Core E5300 2.60GHz, memory 2G, Windows XP SP3.

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Abstract

The invention provides an SAR image registration method based on SIFT and normalized mutual information. The method includes the steps that firstly, a standard image I1 and an image to be registered I2 are input and are respectively pre-processed; secondly, features of the pre-processed image I1 and features of the pre-processed image I2 are extracted according to the MM-SIFT method to acquire initial feature point pairs Fc and SIFT feature vectors Fv1 and Fv2; thirdly, initial matching is carried out through the Fv1 and the Fv2; fourthly, the Fc is screened for the second time according to the RANSAC strategy of a homography matrix model, final correct matching point pairs Fm are acquired, and a registration parameter pr is worked out according to the least square method; fifthly, I2 is subjected to space conversion through affine transformation, and a roughly-registered image I3 is acquired through interpolation and resampling; sixthly, pr serves as the initial value of normalization information registration, I1 and I2 are subjected to fine registration through the normalized mutual information method, a final registration parameter pr1 is worked out, and a registered image I4 is output. The method can be quickly, effectively and stably carried out, and SAR image registration precision and robustness are improved.

Description

technical field [0001] The invention belongs to the technical field of image processing, and in particular relates to a SAR image registration method based on SIFT and normalized mutual information, which is applied to the fields of image fusion, target detection, landscape and map matching, image navigation and the like. Background technique [0002] Synthetic Aperture Radar (SAR) is a long-distance, non-contact tool for earth observation. As an active imaging radar, it has the characteristics of all-weather and all-day work, and can effectively identify camouflage and penetrate vegetation on the ground to obtain high-resolution SAR images. It has increasingly become one of the most representative means of earth observation. . Registration methods can be roughly divided into two categories: image registration methods based on gray correlation and image registration methods based on features. [0003] Although the image registration method based on gray-scale correlation i...

Claims

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Application Information

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IPC IPC(8): G06T7/00
Inventor 王爽焦李成王云飞陈凯马文萍马晶晶侯彪张楠
Owner XIDIAN UNIV
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