C++ OpenCV视频摄像头图片读写操作

总结一下C++语言下OpenCV的基本读写操作。

头文件导入和CMakeLists.txt

#include<opencv2/opencv.hpp>
#include<iostream>

注意，需要引入命名空间cv，不然使用open cv的时候就需要加入cv::才行

using namespace cv;

CMakeLists.txt这样写

CMAKE_MINIMUM_REQUIRED(VERSION 2.8.12)
PROJECT(hh_tsr_track)
SET(CMAKE_CXX_STANDARD 11)
find_package(OpenCV REQUIRED)
include_directories(${OpenCV_INCLUDE_DIRS})
add_executable(myopencv main.cpp)
target_link_libraries(myopencv ${OpenCV_LIBS})

图片读取

cv::Mat image = cv::imread("/home/xxx/image/abc.png");

图片保存

//创建白色图片
Mat image = Mat(Size(1366, 768), CV_8UC3, Scalar(255, 255, 255));
imwrite("/home/xxx/image/white.png", image);

视频读取

VideoCapture capture;
capture.open("/home/xxx/myvideo/abc.mp4");
if(!capture.isOpened()){
    
    
    cout<<"Error! Cannot open video!"<<endl;
}
while (true){
    
    
	Mat frame;
	capture >> frame;
	imshow("videodemo", frame);
	waitKey(30);
}
//也可以这样
Mat frame;
while (capture.read(frame)) {
    
    
	imshow("videodemo", frame);
	writer.write(frame);
	char c = waitKey(30);
	waitKey(30);
}
//获取视频文件的一些信息
int width = capture.get(CV_CAP_PROP_FRAME_WIDTH);             //帧宽度
int height = capture.get(CV_CAP_PROP_FRAME_HEIGHT);           //帧高度
int totalFrames = capture.get(CV_CAP_PROP_FRAME_COUNT);       //总帧数
int frameRate = capture.get(CV_CAP_PROP_FPS);                 //帧率

摄像头读取

VideoCapture capture(0);
if(!capture.isOpened()){
    
    
    cout<<"Error! Cannot open camera!"<<endl;
}
while (true){
    
    
	Mat frame;
	capture >> frame;
	imshow("camerademo", frame);
	waitKey(30);
}

视频写入

//注意 fourcc和文件名要匹配，('M', 'J', 'P', 'G')对应.avi，('X', 'V', 'I', 'D')对应.mp4
VideoWriter writer("/home/xxx/myvideo/output.avi", VideoWriter::fourcc('M', 'J', 'P', 'G'),30, cv::Size(1366, 768));
for (int i = 0; i < 1000; ++i){
    
    
	writer.write(frame);
	//或者用<<写入
	writer << frame;
}
writer.release();

实时图片展示

imshow("demo", frame);
waitKey(30);

图片缩放

Size dest_size = Size(1366, 768);
resize(original_image, resized_image, dest_size, 0, 0, INTER_AREA);