Catalog

0. install

1. Read images

2. Show

3. Color conversion cvtcolor

4. preservation

 5. Blocking && Recycling function

0. install

Look at this tutorial

OpenCV4 machine learning （ One ）：OpenCV4+VS2017 Environment construction and configuration _AI Bacteria blog -CSDN Blog _opencv4

This document is good for reference

2_1_ Introduction to image - OpenCV Official documents in Chinese

1. Read images

Use imread() Function to read image .

The first parameter , Image path .

The second parameter is a flag , It specifies how images are read .

• cv.IMREAD_COLOR： Load color image . The transparency of any image will be ignored . It's the default flag .
• cv.IMREAD_GRAYSCALE： Load image in grayscale mode
• cv.IMREAD_UNCHANGED： Load image , Include alpha passageway

Be careful   In addition to these three signs , You can simply pass integers 1、0 or -1.

Warning

Even if the image path is wrong , It doesn't cause any mistakes , But it will give null

// Load image 
	Mat src = imread("F:/opencv/opencv_tutorial_data-master/images/hist_01.jpg");
	// Judge whether the loading is successful 
	if (src.empty()) {
		cout<<"could not load image...\n"<<endl;
		return -1;
	}

2. Show

// Make windows adaptive 
	namedWindow("test opencv setup src",WINDOW_FREERATIO);
	// Show 
	imshow("test opencv setup src", src);

3. Color conversion cvtcolor

	// Color space conversion  cvtcolor
	Mat gray;
	cvtColor(src, gray, COLOR_RGB2GRAY);
	cout << " src.depth " << src.depth() << endl;
	cout << " src.channels " << src.channels() << endl;
	cout << " gray.depth " << gray.depth() << endl;
	cout << " gray.channels " << gray.channels() << endl;
	imshow("test opencv setup gray", gray);
	

4. preservation

// Save image 
	imwrite("F:/opencv/opencv_tutorial_data-master/images/hist_011.jpg",gray);

 5. Blocking && Recycling function

waitKey(0);    
 destroyAllWindows();