SIFT特征提取-应用篇

SIFT特征具有缩放、旋转特征不变性，下载了大牛的matlab版SIFT特征提取代码，解释如下：

1.调用方法：

将文件加入matlab目录后，在主程序中有两种操作：

op1：寻找图像中的Sift特征：

[csharp] view
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[image, descrips, locs] = sift('scene.pgm');   

showkeys(image, locs);  

op2：对两幅图中的SIFT特征进行匹配：

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match('scene.pgm','book.pgm');  

由于scene和book两图中有相同的一本书，但orientation和size都不同，可以发现所得结果中Sift特征检测结果非常好。

2.代码下载地址：

<span style="vertical-align: baseline; color: rgb(19, 61, 182);"><a target=_blank target="_blank" href="http://www.cs.ubc.ca/~lowe/keypoints/" style="color: rgb(19, 61, 182); text-decoration: none; vertical-align: baseline;"><span style="font-family: 'Microsoft YaHei'; font-size: 13px;">http://www.cs.ubc.ca/~lowe/keypoints/</span></a></span>

<span style="font-family: 'Microsoft YaHei'; font-size: 13px;">3.想用自己的图片进行调用：</span>

<span style="font-family: 'Microsoft YaHei'; font-size: 13px;"></span><div class="dp-highlighter bg_csharp" style="font-family: Consolas, 'Courier New', Courier, mono, serif; font-size: 12px; width: 878.5625px; overflow: auto; padding-top: 1px; margin: 18px 0px !important; background-color: rgb(231, 229, 220);"><div class="bar" style="padding-left: 45px;"><div class="tools" style="padding: 3px 8px 10px 10px; font-stretch: normal; font-size: 9px; line-height: normal; font-family: Verdana, Geneva, Arial, Helvetica, sans-serif; color: silver; border-left-width: 3px; border-left-style: solid; border-left-color: rgb(108, 226, 108); background-color: rgb(248, 248, 248);"><strong>[csharp]</strong> <a target=_blank href="http://blog.csdn.net/abcjennifer/article/details/7365882#" class="ViewSource" title="view plain" style="color: rgb(160, 160, 160); text-decoration: none; border: none; padding: 1px; margin: 0px 10px 0px 0px; font-size: 9px; display: inline-block; width: 16px; height: 16px; text-indent: -2000px; background-image: url(http://static.blog.csdn.net/scripts/SyntaxHighlighter/styles/images/default/ico_plain.gif); background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: 0% 0%; background-repeat: no-repeat;">view plain</a><a target=_blank href="http://blog.csdn.net/abcjennifer/article/details/7365882#" class="CopyToClipboard" title="copy" style="color: rgb(160, 160, 160); text-decoration: none; border: none; padding: 1px; margin: 0px 10px 0px 0px; font-size: 9px; display: inline-block; width: 16px; height: 16px; text-indent: -2000px; background-image: url(http://static.blog.csdn.net/scripts/SyntaxHighlighter/styles/images/default/ico_copy.gif); background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: 0% 0%; background-repeat: no-repeat;">copy</a><a target=_blank href="https://code.csdn.net/snippets/135681" target="_blank" title="在CODE上查看代码片" style="color: rgb(160, 160, 160); text-decoration: none; border: none; padding: 1px; margin: 0px 10px 0px 0px; font-size: 9px; display: inline-block; width: 16px; height: 16px; background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: 0% 0%; background-repeat: no-repeat;"><img src="https://code.csdn.net/assets/CODE_ico.png" width="12" height="12" alt="在CODE上查看代码片" style="border: none; max-width: 100%; position: relative; top: 1px; left: 2px;" /></a><a target=_blank href="https://code.csdn.net/snippets/135681/fork" target="_blank" title="派生到我的代码片" style="color: rgb(160, 160, 160); text-decoration: none; border: none; padding: 1px; margin: 0px 10px 0px 0px; font-size: 9px; display: inline-block; width: 16px; height: 16px; background-image: none; background-attachment: initial; background-color: inherit; background-size: initial; background-origin: initial; background-clip: initial; background-position: 0% 0%; background-repeat: no-repeat;"><img src="https://code.csdn.net/assets/ico_fork.svg" width="12" height="12" alt="派生到我的代码片" style="border: none; max-width: 100%; position: relative; top: 2px; left: 2px;" /></a><div style="position: absolute; left: 405px; top: 1050px; width: 18px; height: 18px; z-index: 99;"></div></div></div><ol start="1" class="dp-c" style="padding: 0px; border: none; color: rgb(92, 92, 92); margin: 0px 0px 1px 45px !important; background-color: rgb(255, 255, 255);"><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;"><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">i1=imread(</span><span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'D:\Images\New\Cars\image_0001.jpg'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">);  </span></span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important; background-color: rgb(248, 248, 248);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">i2=imread(<span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'D:\Images\New\Cars\image_0076.jpg'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">);  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">i11=rgb2gray(i1);  </span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important; background-color: rgb(248, 248, 248);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">i22=rgb2gray(i2);  </span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">imwrite(i11,<span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'v1.jpg'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">,</span><span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'quality'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">,80);  </span></span></li><li style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important; background-color: rgb(248, 248, 248);"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">imwrite(i22,<span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'v2.jpg'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">,</span><span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'quality'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">,80);  </span></span></li><li class="alt" style="border-style: none none none solid; border-left-width: 3px; border-left-color: rgb(108, 226, 108); list-style: decimal-leading-zero outside; color: inherit; line-height: 18px; margin: 0px !important; padding: 0px 3px 0px 10px !important;"><span style="margin: 0px; padding: 0px; border: none; color: black; background-color: inherit;">match(<span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'v1.jpg'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">,</span><span class="string" style="margin: 0px; padding: 0px; border: none; color: blue; background-color: inherit;">'v2.jpg'</span><span style="margin: 0px; padding: 0px; border: none; background-color: inherit;">);  </span></span></li></ol></div>

<span style="font-family: 'Microsoft YaHei'; font-size: 13px;">experiment results:</span>

<span style="font-family: 'Microsoft YaHei'; font-size: 13px;"><img src="http://hi.csdn.net/attachment/201203/18/0_1332039524thQs.gif" alt="" style="border: none; max-width: 100%;" />
</span>

<span style="font-family: 'Microsoft YaHei'; font-size: 13px;">scene</span>

book



compare result

EXP2:



C代码：

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// FeatureDetector.cpp : Defines the entry point for the console application.  

//  

  

#include "stdafx.h"  

#include "highgui.h"  

#include "cv.h"  

#include "vector"  

#include "opencv\cxcore.hpp"  

#include "iostream"  

#include "opencv.hpp"  

#include "nonfree.hpp"  

#include "showhelper.h"  

  

using namespace cv;  

using namespace std;  

  

int _tmain(int argc, _TCHAR* argv[])  

{  

    //Load Image   

    Mat c_src1 =  imread( "..\\Images\\3.jpg");  

    Mat c_src2 = imread("..\\Images\\4.jpg");  

    Mat src1 = imread( "..\\Images\\3.jpg", CV_LOAD_IMAGE_GRAYSCALE);  

    Mat src2 = imread( "..\\Images\\4.jpg", CV_LOAD_IMAGE_GRAYSCALE);  

    if( !src1.data || !src2.data )  

    { std::cout<< " --(!) Error reading images " << std::endl; return -1; }  

  

    //sift feature detect  

    SiftFeatureDetector detector;  

    std::vector<KeyPoint> kp1, kp2;  

  

    detector.detect( src1, kp1 );  

    detector.detect( src2, kp2 );  

    SiftDescriptorExtractor extractor;  

    Mat des1,des2;//descriptor  

    extractor.compute(src1,kp1,des1);  

    extractor.compute(src2,kp2,des2);     

    Mat res1,res2;   

    int drawmode = DrawMatchesFlags::DRAW_RICH_KEYPOINTS;  

    drawKeypoints(c_src1,kp1,res1,Scalar::all(-1),drawmode);//在内存中画出特征点  

    drawKeypoints(c_src2,kp2,res2,Scalar::all(-1),drawmode);  

    cout<<"size of description of Img1: "<<kp1.size()<<endl;  

    cout<<"size of description of Img2: "<<kp2.size()<<endl;  

  

    BFMatcher matcher(NORM_L2);  

    vector<DMatch> matches;  

    matcher.match(des1,des2,matches);  

    Mat img_match;  

    drawMatches(src1,kp1,src2,kp2,matches,img_match);//,Scalar::all(-1),Scalar::all(-1),vector<char>(),drawmode);  

    cout<<"number of matched points: "<<matches.size()<<endl;  

    imshow("matches",img_match);  

    cvWaitKey();  

    cvDestroyAllWindows();  

  

    return 0;  

}  

Python代码：

http://blog.csdn.net/abcjennifer/article/details/7639681

关于sift的其他讲解:

http://blog.csdn.net/abcjennifer/article/details/7639681

http://blog.csdn.net/abcjennifer/article/details/7372880

http://blog.csdn.net/abcjennifer/article/details/7365882

from: http://blog.csdn.net/abcjennifer/article/details/7365882