Question

我已经在opencv中完成了与raspberry pi相机接口的代码。我制作了camera.h文件，我将其包含在源文件中。它运作正常。但是，在我的主程序中，我需要在capture_image（）函数中捕获的帧。

我想在函数capture_image（）

的末尾返回帧

这是我的代码：

#include<opencv2/opencv.hpp>  
#include <opencv2/highgui/highgui.hpp>
#include <iostream>
#include <stdio.h>

using namespace cv 
using namespace std;

int n = 0;

static char cam_image[200];

int capture_image() {

VideoCapture capture(2); //try to open string, this will attempt to open it as a video file or image sequence
if (!capture.isOpened()) //if this fails, try to open as a video camera, through the use of an integer param
    capture.open(2);
        if (!capture.isOpened()) {
    cerr << "Failed to open the video device, video file or image sequence!\n" << endl;
    //help(av);
    return 1;
         }
    string window_name = "Reference Image";
        namedWindow(window_name, CV_WINDOW_KEEPRATIO); //resizable window;
    Mat frame;

    capture >> frame;
        if (frame.empty());
    imshow(window_name, frame);
    waitKey(30);
    sprintf(cam_image,"filename%.3d.jpg",n++);
    imwrite(cam_image,frame);
    cout << "Saved " << cam_image << endl;

    return 0;// Actually I want return (frame)
}

错误：

    camera.h: In function ‘int capture_image()’:
    camera.h:34:17: error: invalid conversion from ‘cv::Mat*’ to ‘int’ [-fpermissive]
    camera.h:24:13: warning: address of local variable ‘frame’ returned [enabled by default]

int函数返回int是合乎逻辑的。但是，我不知道如何定义一个 cv :: Mat函数（）。请帮我。

Answer 1

只需将输出Mat作为参考传递，然后将捕获的帧复制到。您通常不希望在没有复制的情况下返回捕获的帧，因为它会被覆盖。

int capture_image(cv::Mat& result)   // *** pass output Mat as reference
{

    VideoCapture capture(2); //try to open string, this will attempt to open it as a video file or image sequence
    if (!capture.isOpened()) //if this fails, try to open as a video camera, through the use of an integer param
        capture.open(2);
    if (!capture.isOpened()) {
        cerr << "Failed to open the video device, video file or image sequence!\n" << endl;
       //help(av);
       return 1;
    }
    string window_name = "Reference Image";
    namedWindow(window_name, CV_WINDOW_KEEPRATIO); //resizable window;

    Mat frame;

    capture >> frame;
    if (!frame.empty())
    {
         frame.copyTo(result);    // *** copy captured frame into output Mat
    }
    imshow(window_name, frame);
    waitKey(30);
    sprintf(cam_image,"filename%.3d.jpg",n++);
    imwrite(cam_image,frame);
    cout << "Saved " << cam_image << endl;

    return 0;// Success
}

Answer 2

＆＃39;返回＆＃39;垫子中的垫子：

int capture_image( Mat & frame)
{
    if ( ! capture.read(frame) )
        return 0;
    return 1;
}



... later:

Mat frame;
int ok = capture_image(frame);
// use frame if ok was true;

OpenCV相机问题：

2 个答案: