opencv学习之VideoCapture

最新推荐文章于 2024-07-26 12:01:01 发布

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本文介绍了一段使用OpenCV从默认摄像头捕获图像并进行边缘检测的C++代码示例。通过VideoCapture类实例化对象并打开摄像头，然后读取摄像头的每一帧图像，并将其转换为灰度图像，最后应用高斯模糊和Canny边缘检测算法。

获取摄像头图像代码

#include "opencv2/opencv.hpp"

using namespace cv;

int main(int, char**)
{
    VideoCapture cap(0); // open the default camera
    if(!cap.isOpened())  // check if we succeeded
        return -1;

    Mat edges;
    namedWindow("edges",1);
    for(;;)
    {
        Mat frame;
        cap >> frame; // get a new frame from camera
        cvtColor(frame, edges, COLOR_BGR2GRAY);
        GaussianBlur(edges, edges, Size(7,7), 1.5, 1.5);
        Canny(edges, edges, 0, 30, 3);
        imshow("edges", edges);
        if(waitKey(30) >= 0) break;
    }
    // the camera will be deinitialized automatically in VideoCapture destructor
    return 0;
}

类成员：

<pre name="code" class="cpp">class CV_EXPORTS_W VideoCapture
{
public:
    CV_WRAP VideoCapture();
    CV_WRAP VideoCapture(const String& filename);		<span style="white-space:pre">	</span>//open video from url;
    CV_WRAP VideoCapture(int device);					//open device

    virtual ~VideoCapture();
    CV_WRAP virtual bool open(const String& filename);<span style="white-space:pre">			</span><span style="font-family: Arial, Helvetica, sans-serif;">						</span><span style="font-family: Arial, Helvetica, sans-serif;">
</span>    CV_WRAP virtual bool open(int device);<span style="white-space:pre">				</span><pre name="code" class="cpp"><span style="white-space:pre">									</span>//<span style="font-family: Arial, Helvetica, sans-serif;">VideoCapture cap(0)   等价于</span><pre name="code" class="cpp"><span style="font-family: Arial, Helvetica, sans-serif;"><span>																		</span>//VideoCapture cap;</span>

<span style="font-family: Arial, Helvetica, sans-serif;"><span>																		</span>//cap.open(0);<span>	</span></span>

CV_WRAP virtual bool isOpened() const; //check if open sucessed CV_WRAP virtual void release(); //close the already opened file or camera. CV_WRAP virtual bool grab(); //The primary use of the function is in multi-camera environments, CV_WRAP virtual bool retrieve(OutputArray image, int flag = 0); virtual VideoCapture& operator >> (CV_OUT Mat& image); virtual VideoCapture& operator >> (CV_OUT UMat& image);


    CV_WRAP virtual bool read(OutputArray image);<span style="white-space:pre">			</span>//cap.read(frame);等价于  cap>>frame;

    CV_WRAP virtual bool set(int propId, double value);
    CV_WRAP virtual double get(int propId);

protected:
    Ptr<CvCapture> cap;
    Ptr<IVideoCapture> icap;
private:
    static Ptr<IVideoCapture> createCameraCapture(int index);
};