c++ opencv 基本操作

下载地址：

https://opencv.org/releases/

归一化，转vector：

Opencv C++ 归一化_jacke121的专栏-CSDN博客_c++ opencv 归一化

c++ 贴图：

opencv c++ 贴图_jacke121的专栏-CSDN博客

c++ transpose：

nanodet onnx踩坑记录_jacke121的专栏-CSDN博客

通道转换

创建图片，rect贴图，读取rect

矩形框：

读取字符串，resize

最大值，最小值

乘法

除法

转flost32类型

打印类型

打印输出

float*内存拷贝

遍历图片

通道转换

c++ opencv 通道转换_jacke121的专栏-CSDN博客_c++通道

创建图片，rect贴图，读取rect

 int width = 360;int height = 30;int width_crop = 180;cv::Mat img(height, width, CV_8UC3, cv::Scalar(0, 0, 255));cv::Mat img2(height, width_crop, CV_8UC3, cv::Scalar(0,255, 0));cv::Rect rect(0, 0, width_crop, height);cv::Mat imageROI = img(rect);img2.copyTo(imageROI, img2);cv::imshow("result", img);cv::waitKey(0);

读取rect

                 float aaa = r.rect.x;float bbb = r.rect.y;float ccc = r.rect.width;float ddd = r.rect.height;std::cout << "aaa " << aaa << " bbb:" << bbb<< " ccc:" << ccc << " ddd:" << ddd << std::endl;

矩形框：

int x = 50;
int y = 50;
int width = 50;
int height = 50;
cv::Rect rect(x, y, width, height);cv::rectangle(matImage,Rect(100,300,20,200),Scalar(0,0,255),1,1,0);

读取字符串，resize

 cv::Mat row_img = cv::imread(R"(G:\rgb/000000.jpg)");int iw = row_img.cols;int ih = row_img.rows;cv::Mat image;cv::resize(row_img, image,cv::Size(INPUT_SIZE,INPUT_SIZE));cv::Mat dst = cv::Mat::zeros(row_img.size(), CV_32FC3);row_img.convertTo(dst, CV_32FC3);// , 10, -1);dst = dst - 128.0;dst = dst / 128.0;std::cout << dst.type() << std::endl;for (int a = 0; a < 20; a++) {//cout << (dst.data)[a] << " ";cout << ((float*)(dst.data))[a] << " ";}

最大值，最小值

opencv4可以多通道计算，opencv3.4只能计算单通道图像。

Mat image1, image3;image1 = imread("D:\\zhengjian.jpg");if (!image1.data){return 0;}double minv = 0.0, maxv = 0.0;minMaxIdx(image1, &minv, &maxv);cout << "Mat minv = " << minv << endl;cout << "Mat maxv = " << maxv << endl;//归一化image_new = (image_new - minVal) / (maxVal - minVal)*255;//转化类型Mat dst = Mat::zeros(image_new.size(), CV_8U);image_new.convertTo(dst, CV_8U);// , NULL, 0);//image_new.convertTo(image_new, CV_8U, 255.0 / (maxVal - minVal), 0);

//建立空的黑图

Mat atom_image = Mat::zeros(w, w, CV_8UC3);

乘法

#include<opencv2/core/core.hpp>
#include<opencv2/highgui/highgui.hpp>
#include<opencv2/imgproc/imgproc.hpp>
#include<vector>
#include<iostream>using namespace std;
using namespace cv;int main()
{Mat image1, image2, image3;image1 = imread("C:\\Users\\Dell\\Desktop\\5.jpg");if (!image1.data){return 0;}image2 = imread("C:\\Users\\Dell\\Desktop\\4.jpg");if (!image2.data){return 0;}resize(image2, image3, image1.size());namedWindow("Image 1");imshow("Image 1", image1);namedWindow("Image 3");imshow("Image 3", image3);Mat result;image3 = image3 * 0.3;image1 = image1 * 0.9;add(image1, image3, result);namedWindow("result");imshow("result", result);waitKey(0);return 0;
}

除法

Mat result1;imshow("result_o", image1);image1 = image1 / 2;imshow("result", image1);

转flost32类型

 cv::Mat image0 = cv::imread("../configs/bus.jpg", cv::IMREAD_UNCHANGED);cv::Mat dst = cv::Mat::zeros(image0.size(), CV_32FC3);image0.convertTo(dst, CV_32FC3);// , 10, -1);

打印类型

以下内容转自：

Package | OpenCV C++ cv::Mat 数据类型type对应的输出值_iLOVEJohnny的博客-CSDN博客_opencv 输出mat数据类型

std::cout << img.type() << std::endl;

id对应数据类型：

+--------+----+----+----+----+------+------+------+------+
| | C1 | C2 | C3 | C4 | C(5) | C(6) | C(7) | C(8) |
+--------+----+----+----+----+------+------+------+------+
| CV_8U | 0 | 8 | 16 | 24 | 32 | 40 | 48 | 56 |
| CV_8S | 1 | 9 | 17 | 25 | 33 | 41 | 49 | 57 |
| CV_16U | 2 | 10 | 18 | 26 | 34 | 42 | 50 | 58 |
| CV_16S | 3 | 11 | 19 | 27 | 35 | 43 | 51 | 59 |
| CV_32S | 4 | 12 | 20 | 28 | 36 | 44 | 52 | 60 |
| CV_32F | 5 | 13 | 21 | 29 | 37 | 45 | 53 | 61 |
| CV_64F | 6 | 14 | 22 | 30 | 38 | 46 | 54 | 62 |
+--------+----+----+----+----+------+------+------+------+

打印输出

注意，每行结尾有 error 标注。

 Mat srcResize = imread(imgpath);for (int a = 0; a < 20; a++) {cout << (int)srcimg.at<uchar>(0, a) << " ";// ok intcout << ((float*)(srcimg.data))[a] << " ";//error}cout << "int \n";cv::Mat dst = cv::Mat::zeros(srcResize.size(), CV_32FC3);srcResize.convertTo(dst, CV_32FC3);// , 10, -1);for (int a = 0; a < 20; a++) {cout << (float)dst.at<float>(0, a) << " ";// ok floatcout << ((float*)(dst.data))[a] << " ";// ok float//cout << setprecision(3) << ((float*)(srcimg.data))[a] << " ";}cout << "\n CV_32FC3 \n";for (int a = 0; a < 20; a++) {cout << setprecision(3) << ((double*)(dst.data))[a] << " ";//error}

这个输出错误：

cout << (dst.data)[a] << " ";

float*内存拷贝

转自：memcpy - how to copy float* to float* variable - 鹅要长大 - 博客园

float* seg_segmap = new float[OUTPUT_H * OUTPUT_W];
float* temp = new float[OUTPUT_H * OUTPUT_W];
//memcpy(temp, seg_segmap, sizeof(seg_segmap));//error
memcpy(temp, seg_segmap, OUTPUT_H * OUTPUT_W*sizeof(float));

遍历图片

 cv::String path = R"(E:\data\Circle-detection-master\train_repeat\image/)";cv::String dst = "result/";//cv::String GT = "D:/astudy/dataset/circle/temp/GT/";T test_threshold;vector<cv::String> Filenames;cv::glob(path, Filenames);float fmeasureSum = 0.0;float precisionSum = 0.0;float recallSum = 0.0;float timeSum = 0.0;// Detect each image in the directory 'Images1'for (int i = 0; i < Filenames.size(); i++){//read imagescv::String file = Filenames[i];