Opencv learning log 28 -- detect the red cup cover

Preface

This article is mainly about opencv Detection of medium red cup cover .

One 、 Detect the red cup cover

// Third question   Detect the red cup cover 
#include <opencv2/opencv.hpp>
#include <iostream>
using namespace cv;
using namespace std;

int main()
{
    
// VideoCapture cap(0);



	double scale = 0.5;

	//0-188
	// Skin colour 
	double i_minH = 150;
	double i_maxH = 255;
	//0-255
	double i_minS = 150;
	double i_maxS = 255;
	//0-255
	double i_minV = 150;
	double i_maxV = 255;

	while (1)
	{
    
		Mat frame;
		Mat hsvMat;
		Mat detectMat;

		 frame= imread("C://Users//john//Desktop//2.jpg");;
		Size ResImgSiz = Size(frame.cols*scale, frame.rows*scale);
		Mat rFrame = Mat(ResImgSiz, frame.type());
		resize(frame, rFrame, ResImgSiz, INTER_LINEAR);
		cvtColor(rFrame, hsvMat, COLOR_BGR2HSV);
		rFrame.copyTo(detectMat);
		cv::inRange(hsvMat, Scalar(i_minH, i_minS, i_minV), Scalar(i_maxH, i_maxS, i_maxV), detectMat);
		vector<vector<Point>> contours;
		vector<Vec4i> hirearchy;
		findContours(detectMat, contours, CV_RETR_LIST, CV_CHAIN_APPROX_NONE);
		int num = contours.size();
		Point2f rect[4];
		for (int i = 0; i < num; i++)
		{
    

			RotatedRect rbox = minAreaRect(contours[i]);
			///cout << rbox << endl;
			int area = contourArea(contours[i]);// Calculate the contour area 
			rbox.points(rect);  // Copy the four ends of the smallest circumscribed rectangle to rect Array 
			if (area >= 40)
			{
    
				drawContours(detectMat, contours, i, Scalar(255, 0, 0), -1, 8);

				for (int j = 0; j < 4; j++)
				{
    
					line(rFrame, rect[j], rect[(j + 1) % 4], Scalar(255, 255, 255), 2, 8);  // Draw the smallest outer edge of each rectangle 
				}
			}
		}
		imshow("while: in the range ", detectMat);
		imshow("frame", rFrame);
		waitKey(30);



	}

}

summary

1. The code can run directly , If you don't understand, please leave a message .