opencv 4.4 install VS2019

1. Preparation

1. Download the opencv4.4.0 exe ​​file from the official website and extract it to the specified folder

2. Add the conversion variable F:\file\opencv\opencv\build\x64\vc15\bin to the path. I am using vs2019, so vc14 is not added.

3. Copy opencv_world440.dll and opencv_world440d.dll to the folder C:\Windows\SysWOW64.
Note: 64-bit system users need to pay attention. The 32-bit DLL files are placed in [C:\Windows\SysWOW64], and the 64-bit ones are placed in [C:\Windows\SysWOW64]. The DLL file is placed in "[C:\Windows\System32].

4. Open vs2019 and create a new command line program. After the creation is successful, open the property manager. First select the specified configuration manager.

Add to the include directory:
F:\file\opencv\opencv\build\include
Add to the library directory:
F:\file\opencv\opencv\build\x64\vc15\lib
Select input -> Additional dependencies Add opencv_world440d.lib ( Make changes according to the actual version downloaded. It can be viewed in opencv\build\x64\vc15\lib)

5. Test it and read a photo

#include <opencv2/opencv.hpp>

int main(int argc, char** argv) {
    
    
	cv::Mat img = cv::imread("F:\\file\\abcdefg.jpg");
	if (img.empty()) {
    
    
		printf("资源未找到");
		return -1;
	}
	cv::namedWindow("Example1", cv::WINDOW_AUTOSIZE);
	cv::imshow("Example1", img);
	cv::waitKey(0);
	cv::destroyWindow("Example1");
	return 0;
}

2. Start

1. Read a video

#include <opencv2/opencv.hpp>

int main(int argc, char** argv) {
    
    
	cv::namedWindow("Example2", cv::WINDOW_AUTOSIZE);
	cv::VideoCapture cap;
	cap.open("F:\\file\\VID_20200131_115507.mp4");
	cv::Mat Frame;
	for (;;) {
    
    
		cap >> Frame;
		if (Frame.empty()) break;
		cv::imshow("Example2", Frame);
		if (cv::waitKey(33) >= 0) break; //等待输入，时长为33毫秒；
		//30FPS播放，准确数字为33.3ms...,60FPS则设置等待（1000/60）ms
	}

	return 0;
}

2. Video player with progress bar

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

using namespace std;

int g_slider_position = 0;
int g_run = 1, g_dontset = 0;//start out int single step mode
cv::VideoCapture g_cap;

void onTrackbarSlide(int pos, void*) {
    
    
	g_cap.set(cv::CAP_PROP_POS_FRAMES, pos);

	if (!g_dontset)
		g_run = 1;
	g_dontset = 0;
}

int main(int argc, char** argv) {
    
    
	
	cv::namedWindow("Example2_4", cv::WINDOW_AUTOSIZE); //创建一个窗口

	g_cap.open("F:\\file\\VID_20200131_115507.mp4"); //将指定的视频读取到g_cap中
	int frames = (int)g_cap.get(cv::CAP_PROP_FRAME_COUNT); //获取视频的总帧数
	int tmpw = (int)g_cap.get(cv::CAP_PROP_FRAME_WIDTH); //获取视频的宽度
	int tmph = (int)g_cap.get(cv::CAP_PROP_FRAME_HEIGHT); //获取视频的高度
	cout << "Video has" << frames << "frames of dimensions("
		<< tmpw << "," << tmph << ")." << endl;

	cv::createTrackbar("Position", "Example2_4", &g_slider_position, frames,
		onTrackbarSlide);//创建进度条
	cv::Mat frame;
	for (;;) {
    
    
		if (g_run != 0) {
    
    
			g_cap >> frame;
			if (frame.empty()) break;
			int current_pos = (int)g_cap.get(cv::CAP_PROP_POS_FRAMES); //获取当前的帧数位置
			g_dontset = 1;

			cv::setTrackbarPos("Position", "Example2_4", current_pos);
			cv::imshow("Example2_4", frame);

			g_run -= 1;
		}

		char c = (char)cv::waitKey(10);
		if(c=='s')//single step
		{
    
    
			g_run = 1; cout << "Single step,run=" << g_run << endl;
		}
		if (c == 'r')//run mode
		{
    
    
			g_run = -1; cout << "Run mode,run=" << g_run << endl;
		}
		if (c == 27)
			break;
	}
	return 0;
}

3. Gaussian kernel spatial filtering

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

using namespace std;


//简单处理函数
void example2_5(const cv::Mat& image) {
    
    
	//创建连个窗口用来显示出入和输出的图像
	cv::namedWindow("Example2_5-in", cv::WINDOW_NORMAL);
	cv::namedWindow("Example2_5-out", cv::WINDOW_NORMAL);

	cv::imshow("Example2_5-in", image);

	cv::Mat out; //输出的图像

	//高斯核模糊滤波
	cv::GaussianBlur(image, out, cv::Size(5, 5), 3, 3);
	cv::GaussianBlur(out, out, cv::Size(5, 5), 3, 3);

	//将处理后的图像打印在输出窗口
	cv::imshow("Example2_5-out", out);

	cv::waitKey(0);
}

int main(int argc, char** argv) {
    
    
	
	cv::Mat image = cv::imread("F:\\file\\abcdefg.jpg");

	example2_5(image);

	return 0;
}

When creating a window, AUTOSIZE will automatically adjust the window to the size of the wrapped image, but there is a maximum value. When the image exceeds the maximum value, the image will not be fully displayed. When using the NORMAL parameter, a fixed-size window will be created, and the image will be Scale to fit window size