在打开的cv c ++中单击鼠标右键时如何从视频中捕获图像

Question

我正在使用 open cv ，我在从视频中捕获图像时遇到了问题。 我的基本需求是，当视频在 open cv 中运行时，只要我单击鼠标程序的右键应该从视频中捕获图像，然后图像应该保存在任何位置。在保存的图像之后，我必须执行进一步的图像处理。 请任何人帮助我。

Answer 1

这很简单。您需要鼠标回调、写入图像和运行剪辑，因此这是我为您提出问题的代码。

#include <iostream>
#include <string>
#include <sstream>
#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>



cv::Mat currentFrame;

 static void onMouse( int event, int x, int y, int, void* )
 {
    static int count(0);
    if ( event == cv::EVENT_RBUTTONDOWN ) {

      std::stringstream ss;
      ss << count;
      std::string countStr = ss.str();
      std::string imageName = "image_" + countStr;
      std::string FullPath = "/home/xxxx/" + imageName + ".jpg";
      cv::imwrite( FullPath, currentFrame );
      std::cout << " image has been saved " << std::endl;
      ++count;
   }
 }

int main()
{

    std::string clipFullPath = "/home/xxxx/drop.avi";
    cv::VideoCapture clip(clipFullPath);      

    if ( !clip.isOpened() ){
        std::cout  << "Error: Could not open the  video: " << std::endl;
        return -1;
    }


    cv::namedWindow("Display", CV_WINDOW_AUTOSIZE);
    cv::setMouseCallback("Display", onMouse, 0 );

    for(;;){

       clip >> currentFrame;  

        if ( currentFrame.empty() ) 
              break;        

        cv::imshow("Display", currentFrame);
        cv::waitKey(30);

    }
    return 0;
}

std::to_string() 需要 -std=c++11。如果您想通过 GUI 窗口保存图像，我认为您需要另一个库，例如支持此功能的 Qt。

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已编辑：OP 需要从网络摄像头而不是视频中捕获帧。

这是评论中您问题的代码。

#include <iostream>
#include <cstdlib>
#include <string>
#include <sstream>
#include "opencv2/core/core.hpp"
#include "opencv2/highgui/highgui.hpp"


cv::Mat frame;

 static void onMouse( int event, int x, int y, int, void* )
 {
    static int count(0);
    if ( event == cv::EVENT_RBUTTONDOWN ) {

      std::stringstream ss;
      ss << count;
      std::string countStr = ss.str();
      std::string imageName = "image_" + countStr;
      std::string FullPath = imageName + ".jpg"; // save to the current directory
      cv::imwrite( FullPath, frame );
      std::cout << " image has been saved " << std::endl;
      ++count;
   }
}


int main()
{
    // access the default webcam 
    cv::VideoCapture cap(0); 

    // Double check the webcam before start reading. 
    if ( !cap.isOpened() ){ 
        std::cerr  << "Cannot open the webcam " << std::endl;
        exit (EXIT_FAILURE);
    }

    cv::namedWindow("webcam",CV_WINDOW_AUTOSIZE);
    cv::setMouseCallback("webcam", onMouse, 0 );

    while ( true ){

       // acquire frame 
       cap >> frame;

       // Safety checking 
       if ( !frame.data ){ 
         std::cerr << "Cannot acquire frame from the webcam " << std::endl;
            break;
       }

       cv::imshow("webcam", frame); 

       if ( cv::waitKey(30) == 27){
        std::cout << "esc key is pressed" << std::endl;
        break; 
       }
    }

    return 0;
} 

图像保存在可执行文件的目录中。在终端命令中（即我使用的是 Mac 和 OpenCV 2.4.11）

g++ main.cpp -o main -I/opt/local/include -L/opt/local/lib -lopencv_highgui.2.4.11 -lopencv_core.2.4.11