三帧间差分法

三帧差法
目的：解决帧间差分法的“双影”问题。算法步骤如下：
（1） Det1=framePre-framePrePre；
（2） Det2=frameNow-framePre；
（3） frameDet=Det1&Det2；
（4）形态学处理（如dilate）.

************************************************************************/
#include  
#include  
#include  
#include 
#include 
using namespace cv;
using namespace std; 

cv::Mat frame;
cv::Mat result;
char image_name[25];

//三帧间差分
int main()
{
    int i=0;
    cv::Mat framePrePre, framePre, frameNow, frameDet;
    cv::Mat contours, contoursInv;
    cv::Mat Det1, Det2;
    VideoCapture capture("Crowd-Activity-All.avi");
    if (!capture.isOpened())
    {
        return 0;
    }
    double videoFPS = capture.get(CV_CAP_PROP_FPS);  //获取帧率  
    double videoPause = 1000 / videoFPS;
    std::cout << videoFPS << endl;
    std::cout << videoPause << endl;
    capture >> framePrePre;
    capture >> framePre;
    cvtColor(framePrePre, framePrePre, CV_RGB2GRAY);
    cvtColor(framePre, framePre, CV_RGB2GRAY);
    int save = 0;
    bool stop(false);
    while (!stop)
    {
        capture >> frameNow;
        if (frameNow.empty() || waitKey(videoPause) == 27)
        {
            break;
        }
        cvtColor(frameNow, frameNow, CV_RGB2GRAY);
        Mat Det1;
        Mat Det2;
        absdiff(framePrePre, framePre, Det1);  //帧差1  
        absdiff(framePre, frameNow, Det2);     //帧差2  
        threshold(Det1, Det1, 0, 255, CV_THRESH_OTSU);  //自适应阈值化  
        threshold(Det2, Det2, 0, 255, CV_THRESH_OTSU);
        bitwise_and(Det1, Det2, frameDet);
        Mat element = getStructuringElement(0, Size(3, 3));  //膨胀核  
        dilate(frameDet, frameDet, element);    //膨胀  
        dilate(frameDet, frameDet, element);    
        framePrePre = framePre;
        framePre = frameNow;
        imshow("Video", frameNow);
        imshow("Detection", frameDet);
        sprintf(image_name, ".\\three frames subtraction method_image\\%d.jpg", ++i);
        imwrite(image_name, frameDet);
    }
    return 0;
}

测试通过！