啥話不說，先上程式碼：

#include <opencv2/core/core.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <iostream>

using namespace std;
using namespace cv;

    void onMouse(int event, int x, int y, int flags, void* param)
    {
        Mat *im = reinterpret_cast<Mat*>(param);
        if(event==CV_EVENT_LBUTTONDOWN)
        {
                std::cout<<"at("<<x<<","<<y<<")value is:"
                    <<static_cast<int>(im->at<uchar>(cv::Point(x,y)))<<std::endl;
        }
    }
int main(int argc, char *argv[])
{
    VideoCapture capture("1.avi");
    if(!capture.isOpened())
    {
        cout<<"fail to open."<<endl;
    }
    double rate = capture.get(CV_CAP_PROP_FPS);
    bool stop(false);
    Mat frame;

    char ch;
    cout<<"please input the channel you want to see:"<<endl;
    cin>>ch;

    int delay=1000/rate;
    while(!stop)
    {
        if(!capture.read(frame))
            break;
        vector<Mat> channels;
        Mat dst;
        split(frame,channels);
        switch(ch)
        {
            case 'b':
            dst=channels[0];
            break;
            case 'g':
            dst=channels[1];
            break;
            case 'r':
            dst=channels[2];
            break;
        }

        namedWindow("Img",CV_WINDOW_AUTOSIZE);
        imshow("Img",dst);
        cv::setMouseCallback("Img",onMouse,reinterpret_cast<void*>(&frame));
            if(waitKey(delay)>=0)
            {
                stop=true;
            }
    }
    waitKey(0);
    return 0;
}
 

程式碼解釋：

VideoCapture capture("1.avi");

if(!capture.isOpened())
    {
        cout<<"fail to open."<<endl;
    }

 double rate = capture.get(CV_CAP_PROP_FPS);

 char ch;
    cout<<"please input the channel you want to see:"<<endl;
    cin>>ch;
 

int delay=1000/rate;
if(waitKey(delay)>=0)
            {
                stop=true;
            }

該條件語句下，首先執行waitKey( )，意味著停留一幀的時間，然後進行判斷，由於當delay>0時無按鍵按下時waitKey返回-1，此時若有按鍵按下，則返回該按鍵ASCII碼，則if成立，跳出while迴圈;

if(!capture.read(frame))
            break;

split(frame,channels);
 

switch(ch)
        {
            case 'b':
            dst=channels[0];
            break;
            case 'g':
            dst=channels[1];
            break;
            case 'r':
            dst=channels[2];
            break;
        }

        namedWindow("Img",CV_WINDOW_AUTOSIZE);
        imshow("Img",dst);

 cv::setMouseCallback("Img",onMouse,reinterpret_cast<void*>(&frame));

void onMouse(int event, int x, int y, int flags, void* param)
    {
        Mat *im = reinterpret_cast<Mat*>(param);
        if(event==CV_EVENT_LBUTTONDOWN)
        {
                std::cout<<"at("<<x<<","<<y<<")value is:"
                    <<static_cast<int>(im->at<uchar>(cv::Point(x,y)))<<std::endl;
        }
    }