本文主要是介绍前景检测算法_4(opencv自带GMM),希望对大家解决编程问题提供一定的参考价值,需要的开发者们随着小编来一起学习吧!
前面已经有3篇博文介绍了背景减图方面相关知识(见下面的链接),在第3篇博文中自己也实现了gmm简单算法,但效果不是很好,下面来体验下opencv自带2个gmm算法。
opencv实现背景减图法1(codebook和平均背景法)
http://www.cnblogs.com/tornadomeet/archive/2012/04/08/2438158.html
opencv实现背景减图法2(帧差法)
http://www.cnblogs.com/tornadomeet/archive/2012/05/01/2477629.html
opencv实现背景减图法3(GMM)
http://www.cnblogs.com/tornadomeet/archive/2012/06/02/2531565.html
工程环境opencv2.3.1+vs2010
实现功能:与上面第三篇博文一样,完成动态背景的训练,来检测前景。
数据来源和前面的一样: http://research.microsoft.com/en-us/um/people/jckrumm/WallFlower/TestImages.htm 由于该数据是286张bmp格式的图片,所以用的前200张图片来作为GMM参数训练,后186张作为测试。训练的过程中树枝被很大幅度的摆动,测试过程中有行人走动,该行人是需要迁就检测的部分。
Opencv自带的gmm算法1的实验结果如下:
其工程代码如下:
1 // gmm_wavetrees.cpp : 定义控制台应用程序的入口点。2 //3 4 #include "stdafx.h"5 6 #include "opencv2/core/core.hpp"7 #include "opencv2/video/background_segm.hpp"8 #include "opencv2/highgui/highgui.hpp"9 #include "opencv2/imgproc/imgproc.hpp"10 #include <stdio.h>11 12 using namespace std;13 using namespace cv;14 15 //this is a sample for foreground detection functions16 string src_img_name="WavingTrees/b00";17 const char *src_img_name1;18 Mat img, fgmask, fgimg;19 int i=-1;20 char chari[500];21 bool update_bg_model = true;22 bool pause=false;23 24 //第一种gmm,用的是KaewTraKulPong, P. and R. Bowden (2001).25 //An improved adaptive background mixture model for real-time tracking with shadow detection.26 BackgroundSubtractorMOG bg_model;27 28 void refineSegments(const Mat& img, Mat& mask, Mat& dst)29 {30 int niters = 3;31 32 vector<vector<Point> > contours;33 vector<Vec4i> hierarchy;34 35 Mat temp;36 37 dilate(mask, temp, Mat(), Point(-1,-1), niters);//膨胀,3*3的element,迭代次数为niters38 erode(temp, temp, Mat(), Point(-1,-1), niters*2);//腐蚀39 dilate(temp, temp, Mat(), Point(-1,-1), niters);40 41 findContours( temp, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE );//找轮廓42 43 dst = Mat::zeros(img.size(), CV_8UC3);44 45 if( contours.size() == 0 )46 return;47 48 // iterate through all the top-level contours,49 // draw each connected component with its own random color50 int idx = 0, largestComp = 0;51 double maxArea = 0;52 53 for( ; idx >= 0; idx = hierarchy[idx][0] )//这句没怎么看懂54 {55 const vector<Point>& c = contours[idx];56 double area = fabs(contourArea(Mat(c)));57 if( area > maxArea )58 {59 maxArea = area;60 largestComp = idx;//找出包含面积最大的轮廓61 }62 }63 Scalar color( 0, 255, 0 );64 drawContours( dst, contours, largestComp, color, CV_FILLED, 8, hierarchy );65 }66 67 int main(int argc, const char** argv)68 {69 bg_model.noiseSigma = 10;70 img=imread("WavingTrees/b00000.bmp");71 if(img.empty())72 {73 namedWindow("image",1);//不能更改窗口74 namedWindow("foreground image",1);75 namedWindow("mean background image", 1);76 }77 for(;;)78 {79 if(!pause)80 {81 i++;82 itoa(i,chari,10);83 if(i<10)84 {85 src_img_name+="00";86 }87 else if(i<100)88 {89 src_img_name+="0";90 }91 else if(i>285)92 {93 i=-1;94 }95 if(i>=230)96 update_bg_model=false;97 else update_bg_model=true;98 99 src_img_name+=chari; 100 src_img_name+=".bmp"; 101 102 img=imread(src_img_name); 103 if( img.empty() ) 104 break; 105 106 //update the model 107 bg_model(img, fgmask, update_bg_model ? 0.005 : 0);//计算前景mask图像,其中输出fgmask为8-bit二进制图像,第3个参数为学习速率 108 refineSegments(img, fgmask, fgimg); 109 110 imshow("image", img); 111 imshow("foreground image", fgimg); 112 113 src_img_name="WavingTrees/b00"; 114 115 } 116 char k = (char)waitKey(80); 117 if( k == 27 ) break; 118 119 if( k == ' ' ) 120 { 121 pause=!pause; 122 } 123 } 124 125 return 0; 126 }
Opencv自带的gmm算法2的实验结果如下:
其工程代码如下:
1 // gmm2_wavetrees.cpp : 定义控制台应用程序的入口点。2 //3 4 #include "stdafx.h"5 6 #include "opencv2/core/core.hpp"7 #include "opencv2/video/background_segm.hpp"8 #include "opencv2/highgui/highgui.hpp"9 #include "opencv2/imgproc/imgproc.hpp"10 #include <stdio.h>11 12 using namespace std;13 using namespace cv;14 15 //this is a sample for foreground detection functions16 string src_img_name="WavingTrees/b00";17 const char *src_img_name1;18 Mat img, fgmask, fgimg;19 int i=-1;20 char chari[500];21 bool update_bg_model = true;22 bool pause=false;23 24 //第一种gmm,用的是KaewTraKulPong, P. and R. Bowden (2001).25 //An improved adaptive background mixture model for real-time tracking with shadow detection.26 BackgroundSubtractorMOG2 bg_model;27 28 void refineSegments(const Mat& img, Mat& mask, Mat& dst)29 {30 int niters = 3;31 32 vector<vector<Point> > contours;33 vector<Vec4i> hierarchy;34 35 Mat temp;36 37 dilate(mask, temp, Mat(), Point(-1,-1), niters);38 erode(temp, temp, Mat(), Point(-1,-1), niters*2);39 dilate(temp, temp, Mat(), Point(-1,-1), niters);40 41 findContours( temp, contours, hierarchy, CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE );42 43 dst = Mat::zeros(img.size(), CV_8UC3);44 45 if( contours.size() == 0 )46 return;47 48 // iterate through all the top-level contours,49 // draw each connected component with its own random color50 int idx = 0, largestComp = 0;51 double maxArea = 0;52 53 for( ; idx >= 0; idx = hierarchy[idx][0] )54 {55 const vector<Point>& c = contours[idx];56 double area = fabs(contourArea(Mat(c)));57 if( area > maxArea )58 {59 maxArea = area;60 largestComp = idx;61 }62 }63 Scalar color( 255, 0, 0 );64 drawContours( dst, contours, largestComp, color, CV_FILLED, 8, hierarchy );65 }66 67 int main(int argc, const char** argv)68 {69 img=imread("WvingTrees/b00000.bmp");70 if(img.empty())71 {72 namedWindow("image",1);//不能更改窗口73 //cvNamedWindow("image",0);74 namedWindow("foreground image",1);75 // namedWindow("mean background image", 1);76 }77 for(;;)78 {79 if(!pause)80 {81 i++;82 itoa(i,chari,10);83 if(i<10)84 {85 src_img_name+="00";86 }87 else if(i<100)88 {89 src_img_name+="0";90 }91 else if(i>285)92 {93 i=-1;94 }95 // if(i>=230)96 // update_bg_model=false;97 // else update_bg_model=true;98 99 src_img_name+=chari; 100 src_img_name+=".bmp"; 101 102 img=imread(src_img_name); 103 if( img.empty() ) 104 break; 105 106 //update the model 107 bg_model(img, fgmask, update_bg_model ? 0.005 : 0);//计算前景mask图像,其中输出fgmask为8-bit二进制图像,第3个参数为学习速率 108 refineSegments(img, fgmask, fgimg); 109 110 imshow("foreground image", fgimg); 111 imshow("image", img); 112 113 src_img_name="WavingTrees/b00"; 114 115 } 116 char k = (char)waitKey(100); 117 if( k == 27 ) break; 118 119 if( k == ' ' ) 120 { 121 pause=!pause; 122 } 123 } 124 125 return 0; 126 }
可以看出gmm1效果比gmm2的好,但是研究发现,gmm2是在gmm1上改进的,不会越该越差吧,除非2个函数的使用方法不同(虽然函数形式一样),也就是说相同的参数值对函数功能的影响不同。以后有时间在研究了。
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