OpenCV (从头开始写代码)

不忘初心，方得始终，念念不忘，必有回响 —— 《杭高语录》

头文件

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <oprencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

OpenCV库 分为多个模块：

opencv_core 模块包含库的核心功能；

opencv_imgproc 模块包含主要的图像处理函数；

opencv_highgui 模块提供了读写图像和视频的函数以及一些用户交互函数。

图片基操

首先，需要确认调试属性为 Debug x64

装载、显示

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
	
	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	cout << "This image is " << image.rows << " x " << image.cols << endl;
	namedWindow("Original Image");
	imshow("Original Image", image);
	waitKey(0);
	return 0;
}

水平翻转、垂直翻转

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
	
	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	namedWindow("Original Image");
	imshow("Original Image", image);

	Mat result1, result2;
	flip(image, result1, 1);
	flip(image, result2, 0);
	namedWindow("Result 1");
	namedWindow("Result 2");
	imshow("Result 1", result1);
	imshow("Result 2", result2);

	waitKey(0);
	return 0;
}

存储

我的结果保存在 C:\Users\15595\source\repos\Practice (Practice 是工程的名字)

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
	
	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	namedWindow("Original Image");
	imshow("Original Image", image);

	Mat result1;
	flip(image, result1, 1);
	namedWindow("Result 1");
	imwrite("Result.jpg", result1);
	imshow("Result 1", result1);

	waitKey(0);
	return 0;
}

imwrite 函数要写明写入的格式，.jpg .tiff…

转换成灰度图

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
	
	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	cout << "0" << endl;

	Mat grayImg;
	cvtColor(image, grayImg, COLOR_BGR2GRAY);
	namedWindow("Original");
	namedWindow("Gray");
	imshow("Original", image);
	imshow("Gray", grayImg);

	waitKey(0);
	return 0;
}

绘制基本形状

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {
	
	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	circle(image, Point(155, 110), 65, 0, 3);
	putText(image, "This is a dog.", Point(40, 200), FONT_HERSHEY_PLAIN, 2.0, 255, 2);

	namedWindow("Original");
	imshow("Original", image);

	waitKey(0);
	return 0;
}

复制

浅复制和计数引用：图像赋值，图像指向同一个内存块。

深复制：copyTo / convertTo

定义感兴趣区域

（给图片加一个logo吧！）

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {

	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	Mat logo = cv::imread("D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/smalllogo.png");
	Mat imageROI(image, Rect(image.cols - logo.cols, image.rows - logo.rows, logo.cols, logo.rows));

	logo.copyTo(imageROI);

	namedWindow("Original");
	imshow("Original", image);

	waitKey(0);
	return 0;
}

使用图像掩码

（刚刚的logo黑一片，丑丑）

#include <opencv2/core.hpp>
#include <opencv2/imgproc.hpp>
#include <opencv2/highgui.hpp>
#include <iostream>

using namespace cv;
using namespace std;

int main() {

	string path = "D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/puppy.bmp";
	Mat image = imread(path);

	if (image.empty()) {
		cout << "Read Fail ! ! !" << endl;
		return -1;
	}

	Mat logo = cv::imread("D:/Summer Holiday Practice/opencv learning/Resources/OpenCVBook/smalllogo.png");
	Mat imageROI = image(cv::Rect(image.cols - logo.cols, image.rows - logo.rows,logo.cols, logo.rows));
	Mat mask(logo);

	logo.copyTo(imageROI, mask);

	namedWindow("Original");
	imshow("Original", image);

	waitKey(0);
	return 0;
}

原理

掩码试一个8位图像，如果掩码中某个位置的值不为0，在这个位置上的操作就会起作用，如果掩码中某些像素的值为0，那么对图像中相应位置的操作将不起作用。

在上面的代码中，在调用 copyTo 时，使用掩码，可以只复制标志中白色的部分。