Opencv learning basic functions

Catalog

One 、 Color change

Two 、 Gaussian blur

3、 ... and 、 Edge test

Four 、 expansion

Four 、 corrosion

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One 、 Color change

cvtColor（InputArray src,outputArray dst,int code）

The first parameter is the input image ;
The second parameter is the output image ;
The third parameter is the identifier of color space conversion （ See table for details ）;

example ： Image converted to grayscale  

int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\test.png";
	Mat Img = imread(path);
	Mat ImgGray;
	cvtColor(Img, ImgGray, COLOR_BGR2GRAY);
	imshow("Image", Img);
	imshow("Image Gray", ImgGray);
	waitKey(0);
	return 0;
}

Two 、 Gaussian blur

API explain ：

Parameter interpretation ：
. InputArray src:      The input image , It can be Mat type , The image depth is CV_8U、CV_16U、CV_16S、                                CV_32F、CV_64F.
. OutputArray dst:  Output image , Same type and size as the input image .
. Size ksize:            Gaussian kernel size , This size with the first two filters kernel Different sizes ,ksize.width                                      and  ksize.height It can be different but the two values must be positive and odd , If these two values are                                  0, Their value will be sigma Calculation .
. double sigmaX:    The Gaussian kernel function is in X Standard deviation in direction
. double sigmaY:    The Gaussian kernel function is in Y Standard deviation in direction , If sigmaY yes 0, Then the function will automatically                                      sigmaY The value of is set to and sigmaX The same value , If sigmaX and sigmaY All are 0,                                    These two values will be determined by ksize.width and ksize.height Come by calculation . For details, please refer to                                              getGaussianKernel() Function to see the details . It is suggested that size、sigmaX and sigmaY                                  All designated .
. int borderType=BORDER_DEFAULT: Infer some convenient mode of image external pixels , Have default values                                                                           BORDER_DEFAULT, If there is no special need, don't change it                                                                       Change , For details, please refer to borderInterpolate() function .

 

int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\test.png";
	Mat Img = imread(path);
	Mat ImgGray,ImgBlur;
	cvtColor(Img, ImgGray, COLOR_BGR2GRAY);
	GaussianBlur(ImgGray, ImgBlur, Size(11, 11), 3, 3);
	imshow("Image", Img);
	imshow("Image Gray", ImgGray);
	imshow("Image Blur", ImgBlur);
	waitKey(0);
	return 0;
}

3、 ... and 、 Edge test

void Canny(	InputArray image, 
			OutputArray edges,
			double threshold1, 
			double threshold2,
			int apertureSize = 3, 
			bool L2gradient = false);

int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\test.png";
	Mat Img = imread(path);
	Mat ImgGray,ImgBlur,ImgCanny,ImgDil,ImgErode;
	cvtColor(Img, ImgGray, COLOR_BGR2GRAY);
	GaussianBlur(ImgGray, ImgBlur, Size(11, 11), 3, 3);
	Canny(ImgBlur, ImgCanny, 30, 60);
	imshow("Image", Img);
	imshow("Image Gray", ImgGray);
	imshow("Image Blur", ImgBlur);
	imshow("Image Canny", ImgCanny);
	waitKey(0);
	return 0;
}

Four 、 expansion

 （ notes ： First, we should build one that can be used for expansion kernel）

int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\test.png";
	Mat Img = imread(path);
	Mat ImgGray,ImgBlur,ImgCanny,ImgDil,ImgErode;

	cvtColor(Img, ImgGray, COLOR_BGR2GRAY);
	GaussianBlur(ImgGray, ImgBlur, Size(11, 11), 3, 3);
	Canny(ImgBlur, ImgCanny, 30, 60);
	Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3));
	dilate(ImgCanny, ImgDil, kernel);

	imshow("Image", Img);
	imshow("Image Gray", ImgGray);
	imshow("Image Blur", ImgBlur);
	imshow("Image Canny", ImgCanny);
	imshow("Image dilate", ImgDil);
	waitKey(0);
	return 0;
}

Four 、 corrosion

int main() {

	string path = "C:\\Users\\Rong\\Desktop\\Resources\\test.png";
	Mat Img = imread(path);
	Mat ImgGray,ImgBlur,ImgCanny,ImgDil,ImgErode;

	cvtColor(Img, ImgGray, COLOR_BGR2GRAY);
	GaussianBlur(ImgGray, ImgBlur, Size(11, 11), 3, 3);
	Canny(ImgBlur, ImgCanny, 30, 60);
	Mat kernel = getStructuringElement(MORPH_RECT, Size(3, 3));
	dilate(ImgCanny, ImgDil, kernel);
	erode(ImgDil, ImgErode, kernel);

	imshow("Image", Img);
	imshow("Image Gray", ImgGray);
	imshow("Image Blur", ImgBlur);
	imshow("Image Canny", ImgCanny);
	imshow("Image dilate", ImgDil);
	imshow("Image erode", ImgErode);
	waitKey(0);
	return 0;
}