Opencv learning color detection

Catalog

One 、HSV Color space

Two 、 Color detection （inRange function ）

  3、 ... and 、 Track bar

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One 、HSV Color space

H（ tonal ）：0~180

S（ saturation ）：0~255

V（ brightness ）：0~255

Two 、 Color detection （inRange function ）

inRange(imgHSV, Scalar(iLowH, iLowS, iLowV), Scalar(iHighH, iHighS, iHighV), imgThresholded); //Threshold the image

Function for color detection , This function is used to detect src Each of the images Pixels Is it in lowerb and upperb Between , If it is , This pixel is set to 255（ white ）, And keep it in dst Image , Otherwise 0（ black ）.

int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\lambo.png";
	Mat img = imread(path);
	Mat imgHSV, mask;
	int hmin = 0, smin = 110, vmin = 153;
	int hmax = 19, smax = 240, vmax = 255;
	cvtColor(img, imgHSV, COLOR_BGR2HSV);
	Scalar lower(hmin, smin, vmin);   // Lower color value 
	Scalar upper(hmax, smax, vmax);   // The color value of the line 
	inRange(imgHSV, lower, upper, mask);
	imshow("Image", img);
	imshow("Image HSV", imgHSV);
	imshow("Image Mask", mask);

	waitKey(0);
	return 0;
}

  3、 ... and 、 Track bar

int createTrackbar(conststring& trackbarname, conststring& winname, int* value, int count, TrackbarCallback onChange=0,void* userdata=0);

The first parameter ： Name of track bar
The second parameter ： The name of the window
The third parameter ： An integer pointing The pointer , Indicates the position of the slider .
Fourth parameter ： A value that represents the maximum position the slider can reach .PS: The value of the slider is always at the minimum position 0. 

int hmin=0, smin=0, vmin=0, hmax=0, smax=0, vmax=0;
int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\shapes.png";
	Mat Img = imread(path);
	
	Mat src, dst;
	cvtColor(Img, src, COLOR_BGR2HSV);

	// Every time on the track bar   What changes is the value of the variable pointed to by the pointer 
	namedWindow("TrackBar",(700,700));
	createTrackbar("Hmin", "TrackBar", &hmin, 180);
	createTrackbar("Hmax", "TrackBar", &hmax, 180);
	createTrackbar("Smin", "TrackBar", &smin, 255);
	createTrackbar("Smax", "TrackBar", &smax, 255);
	createTrackbar("Vmin", "TrackBar", &vmin, 255);
	createTrackbar("Vmax", "TrackBar", &vmax, 255);
	

	while (true) {
		// So we can detect when the variables on those track bars change   What does the image look like 
		Scalar lower(hmin, smin, vmin);
		Scalar upper(hmax, smax, vmax);

		inRange(src, lower, upper, dst);
		imshow("Image src", src);
		imshow("Image dst", dst);
		// notes ： Here is 1
		waitKey(1);
	}

	return 0;
}