OPENCV study notes base threshold of operation

Include the header file, there are a lot of doubts, and when you want to include what kind of header files

#include<opencv2/opencv.hpp>
//#include<opencv2/core/core.hpp>
//#include<opencv2/highgui/highgui.hpp>
//#include<opencv2/imgproc/imgproc.hpp>
//#include<iostream>
#include<math.h>
using namespace cv;
using namespace std;

Definition of variables and function declarations

Mat src, gray, dst;
int threshold_value =127;
int type_value=2;
int type_max = 4;
int threshold_max = 255;
const char*output_title = "binary image";
void Threshold_Demo(int, void*);

The main function:

int main(int angc, char** argv)
{
	src = imread("1.jpg");
	cvtColor(src, gray, COLOR_RGB2GRAY);//转为灰度图。
    imshow("载入灰度图", gray);
//另一想法是直接 src=imread("1.jpg"，0)；//载入灰度图
			 //imshow("载入灰度图", src);
	namedWindow(output_title, WINDOW_AUTOSIZE);


	createTrackbar("阈值", output_title, &threshold_value, threshold_max, Threshold_Demo);//滑块名称，窗口名称，改变的量，量的最大值，
	createTrackbar("模式", output_title, &type_value, type_max, Threshold_Demo);
	Threshold_Demo(0, 0);

	waitKey(0);
	return(0);
	
}

Threshold_Demo () function

void Threshold_Demo(int, void*)
{
	printf("%d", THRESH_BINARY);
	threshold(gray, dst, threshold_value, threshold_max, type_value);
	imshow(output_title, dst);
}