• 载入函数

Mat imread( const String& filename, int flags = IMREAD_COLOR );
IMREAD_UNCHANGED   = -1, //!< If set, return the loaded image as is (with alpha channel, otherwise it gets cropped).
IMREAD_GRAYSCALE   = 0,  //!< If set, always convert image to the single channel grayscale image.
IMREAD_COLOR       = 1,  //!< If set, always convert image to the 3 channel BGR color image.
IMREAD_ANYDEPTH    = 2,  //!< If set, return 16-bit/32-bit image when the input has the corresponding depth, otherwise convert it to 8-bit.
IMREAD_ANYCOLOR    = 4,  //!< If set, the image is read in any possible color format.
Mat img = imread("D:/learn/dota.jpg");

• 显示函数

imshow("dota", img);

• 输出函数

bool imwrite( const String& filename, InputArray img,
              const std::vector<int>& params = std::vector<int>());
imwrite("D:/new_dota.jpg", img);

• 实例

  #include <iostream>  
  #include <opencv2/core/core.hpp>  
  #include <opencv2/highgui/highgui.hpp>  
  using namespace cv;
  int main() {
    //图像显示
    Mat logo = imread("D:/learn/logo.jpg");
    imshow("logo", logo);
  
    //图像混合
    Mat img = imread("D:/learn/dota.jpg");
    imshow("img", img);
    Mat imgROI;
    imgROI = img(Rect(800, 350, logo.cols, logo.rows));
    //logo加载到背景图
    addWeighted(imgROI,0.5,logo,0.3,0,imgROI);
    imshow("dota_logo", img);
  
    //保存混合的图像
    imwrite("D:/learn/dota_logo.jpg",img);
    waitKey(0);
  }
  

  
  
  
  

• 读取视频文件 调用摄像头 写入视频文件

  #include <iostream>
  #include <opencv2/opencv.hpp>
  using namespace std;
  using namespace cv;
  int main() {
    namedWindow("cap", cv::WINDOW_AUTOSIZE);
    VideoCapture cap;
    Mat frame;
    cap.open(0);
  
    //视频流写出
    Size size = Size(cap.get(CV_CAP_PROP_FRAME_WIDTH), cap.get(CV_CAP_PROP_FRAME_HEIGHT));
    VideoWriter writer;
    writer.open("test.avi", -1, 10, size);
    //
  
    for (;;){
        cap >> frame;
        imshow("out", frame);
        writer << frame;
        if (waitKey(33) >= 0) break;
    }
    cap.release();
    //waitKey(0);
    return 0;
  }
  

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