OpenCV写入不起作用 [英] OpenCV imwrite is not working

问题描述

我有一个简单的OpenCV应用程序，该应用程序从网络摄像头获取视频流，按下spacebar时，它将捕获当前图像并冻结在该图像上.当我尝试使用cv::imwrite()方法将图片保存到磁盘时，它不起作用.该代码可以成功编译，但不会保存图像.它也从调用中返回一个假值.我不确定这是否是图像类型或其他问题，但是我似乎很困惑.

I have a simple OpenCV application that takes a video stream from the webcam, and when the spacebar is pressed it captures the current image and freezes on that image. When I try to use the cv::imwrite() method to save the picture to disk, it does not work. The code successfully compiles but it does not save the image. It is returning a false value as well from the call. I am not sure if this is an issue of type of image or something else, but I seem to be stumped.

这是我当前的cpp类的代码:

Here is the code for my current cpp class:

#include <iostream>

#include "opencv2/imgproc/imgproc.hpp"
#include "opencv2/highgui/highgui.hpp"

using namespace std;
using namespace cv;

Mat picture;
char key;

class FacialRec {

};

int main() {
    //Starting the video
    VideoCapture videoCapture(0);

    if (!videoCapture.isOpened()) {
        cout << "Unable to open video file." << endl;
        return 1;
    }

    namedWindow("Webcam", CV_WINDOW_AUTOSIZE);

    while(true) {
        Mat frame;
        videoCapture.retrieve(frame);
        bool success = videoCapture.read(frame);

        if (!success) {
            cout << "Could not read from video file" << endl;
            return 1;
        }

        imshow("Webcam", frame);
        key = waitKey(30);

        if (key == 27) { //escape key pressed: stop program
            cout << "ESC pressed. Program closing..." << endl;
            break;
        }else if (key == ' ') { //spacebar pressed: take a picture
            picture = frame;
            key = -1;

            while (true) {
                imshow("Webcam", picture);

                key = waitKey(30);

                if (key == 27 || key == 32) {
                    cout << "ESC or SPACE pressed. Returning to video..." << endl;
                    break;
                }

                if (key == 115) {
                    //trying to save to current directory
                    bool maybe = imwrite("/testimage.jpg", picture);
                    // maybe bool is always getting value of 0, or false
                   cout << "s was pressed. saving image " << maybe << endl;
                }   
            }
        }

    }

    return 0;
}

推荐答案

您正在尝试将testimage.jpg写入/目录.执行程序可能没有足够的权限来写入该目录.根据您的评论，您可能想要

You are attempting to write testimage.jpg to the / directory. The executing program probably doesn't have sufficient permissions to write to that directory. Based on your comment, you probably want

//trying to save to current directory
bool maybe = imwrite("./testimage.jpg", picture);

因为.表示当前工作目录.

Since . denotes the current working directory.

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