25局部与分割-帧差法

25局部与分割-帧差法

主要思想：

通过当前帧的灰度图(currentGrayFrame)和前一帧的灰度图(previousGrayFrame)的差，进行像素级的比较

优点：

实时性高

缺点：

1、运动物体本身颜色相近时，会出现较大的空洞。

2、无法应对光照骤变的情况

<span style="font-family:'Microsoft YaHei';font-size:14px;">
#include<iostream>  
using namespace std;  
#include<opencv2\core\core.hpp>  
#include<opencv2\highgui\highgui.hpp>  
#include<opencv2\imgproc\imgproc.hpp>  
using namespace cv;  

const unsigned char FORE_GROUD = 255;  
int thresh = 10;  

int main(int argc,char*argv[])  
{     

    VideoCapture video(argv[1]);  

    //判断如果video是否可以打开  
    if(!video.isOpened())  
        return -1;  

    //用于保存当前帧的图片  
    Mat currentBGRFrame;  

    //用来保存上一帧和当前帧的灰度图片  
    Mat previousSecondGrayFrame;  
    Mat previousFirstGrayFrame;  
    Mat currentGaryFrame;  

    //保存两次的帧差  
    Mat previousFrameDifference;//previousFrameFirst - previousFrameSecond的差分  
    Mat currentFrameDifference;//currentFrame - previousFrameFirst;  

    //用来保存帧差的绝对值  
    Mat absFrameDifferece;  

    //用来显示前景  
    Mat previousSegmentation;  
    Mat currentSegmentation;  
    Mat segmentation;  


    //显示前景  
    namedWindow("segmentation",1);  
    createTrackbar("阈值:","segmentation",&thresh,FORE_GROUD,NULL);  

    //帧数  
    int numberFrame = 0;  

    //形态学处理用到的算子  
    Mat morphologyKernel = getStructuringElement(MORPH_RECT,Size(3,3),Point(-1,-1));  

    for(;;)  
    {  
        //读取当前帧  
        video >> currentBGRFrame;  

        //判断当前帧是否存在  
        if(!currentBGRFrame.data)  
            break;  

        numberFrame++;  
        //颜色空间的转换  
        cvtColor(currentBGRFrame,currentGaryFrame,COLOR_BGR2GRAY);  

        if( numberFrame == 1)  
        {  
            //保存当前帧的灰度图  
            previousSecondGrayFrame = currentGaryFrame.clone();  

            //显示视频  
           imshow("video",currentBGRFrame);  
            continue;  
        }  
        else if( numberFrame == 2)  
        {  
            //保存当前帧的灰度图  
            previousFirstGrayFrame = currentGaryFrame.clone();  

            //previousFirst - previousSecond  
            subtract(previousFirstGrayFrame,previousSecondGrayFrame,previousFrameDifference,Mat(),CV_16SC1);  

            //取绝对值  
            absFrameDifferece = abs(previousFrameDifference);  

            //位深的改变  
            absFrameDifferece.convertTo(absFrameDifferece,CV_8UC1,1,0);  

            //阈值处理  
            threshold(absFrameDifferece,previousSegmentation,double(thresh),double(FORE_GROUD),THRESH_BINARY);  

            //显示视频  
           imshow("video",currentBGRFrame);  
            continue;  
        }  

        else  
        {  
            //src1-src2  
            subtract(currentGaryFrame,previousFirstGrayFrame,currentFrameDifference,Mat(),CV_16SC1);  

            //取绝对值  
            absFrameDifferece = abs(currentFrameDifference);  

            //位深的改变  
            absFrameDifferece.convertTo(absFrameDifferece,CV_8UC1,1,0);  

            //阈值处理  
            threshold(absFrameDifferece,currentSegmentation,double(thresh),double(FORE_GROUD),THRESH_BINARY);  

            //与运算  
            bitwise_and(previousSegmentation,currentSegmentation,segmentation);  

            //中值滤波  
            medianBlur(segmentation,segmentation,3);  

            //形态学处理(开闭运算)  
            //morphologyEx(segmentation,segmentation,MORPH_OPEN,morphologyKernel,Point(-1,-1),1,BORDER_REPLICATE);  
            morphologyEx(segmentation,segmentation,MORPH_CLOSE,morphologyKernel,Point(-1,-1),2,BORDER_REPLICATE);  


            //找边界  
            vector< vector<Point> > contours;  
            vector<Vec4i> hierarchy;  
            //复制segmentation  
            Mat tempSegmentation = segmentation.clone();  
            findContours( segmentation, contours, hierarchy, CV_RETR_EXTERNAL, CV_CHAIN_APPROX_SIMPLE, Point(0, 0) );//CV_RETR_TREE  
            vector< vector<Point> > contours_poly( contours.size() );  

            /*存储运动物体*/  
            vector<Rect> boundRect;  
            boundRect.clear();  

            //画出运动物体  
            for(int index = 0;index < contours.size() ;index++)  
            {  
                approxPolyDP( Mat(contours[index]), contours_poly[index], 3, true );  
                Rect rect =  boundingRect( Mat(contours_poly[index]) );  
                rectangle(currentBGRFrame,rect,Scalar(0,255,255),2);  
            }  

            //显示视频  
           imshow("video",currentBGRFrame);  

           //前景检测  
            imshow("segmentation",segmentation);  

            //保存当前帧的灰度图  
            previousFirstGrayFrame = currentGaryFrame.clone();  

            //保存当前的前景检测  
            previousSegmentation = currentSegmentation.clone();  
        }  

        if(waitKey(33) == 'q')  
            break;  

    }  
    return 0;  
}  

结果如下：