1. 寻找匹配物体

1.1 mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <opencv2/opencv.hpp>#include <QImage>
#include <QString>
#include <QPixmap>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow {Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();void initMainWindow();void imgproc();void imgShow();private slots:void on_pushButton_clicked();private:Ui::MainWindow *ui;cv::Mat myImg;  // 缓存图片：用于代码引用和处理QImage myQImg;  // 保存图片，可转为文件存盘或显示
};
#endif // MAINWINDOW_H

1.2 mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) {ui->setupUi(this);initMainWindow();
}MainWindow::~MainWindow() {delete ui;
}// 界面初始化
void MainWindow::initMainWindow() {// 读取图片cv::Mat imgData = cv::imread("D:\\BaiduNetdiskDownload\\search_pic\\search_pic\\mermaid.jpg");// 图片格式转换cv::cvtColor(imgData, imgData, cv::COLOR_BGR2RGB);myImg = imgData;myQImg = QImage((const unsigned char*)(imgData.data), imgData.cols, imgData.rows, QImage::Format_RGB888);imgShow();  // 显示图片
}// 处理图片
void MainWindow::imgproc() {// CV_TM_CCOEFF 相关匹配，把原图像素对其均值的相对值与待匹配子图像素对其均值的相对值进行比较，计算数值越接近 1，表示匹配度越高int METHOD = CV_TM_CCOEFF;cv::Mat imgSrc = myImg;  // 将被显示的原图// 待匹配的子图cv::Mat imgTmp = cv::imread("D:\\BaiduNetdiskDownload\\search_pic\\search_pic\\fish.jpg");cv::cvtColor(imgTmp, imgTmp, cv::COLOR_BGR2RGB);cv::Mat imgRes;cv::Mat imgDisplay;imgSrc.copyTo(imgDisplay);int rescols = imgSrc.cols - imgTmp.cols + 1;int resrows = imgSrc.rows - imgTmp.rows + 1;imgRes.create(rescols, resrows, CV_32FC1);  // 创建输出结果的矩阵cv::matchTemplate(imgSrc, imgTmp, imgRes, METHOD);  // 进行匹配cv::normalize(imgRes, imgRes, 0, 1, cv::NORM_MINMAX, -1, cv::Mat());  // 进行标准化double minVal;double maxVal;cv::Point minLoc;cv::Point maxLoc;cv::Point matchLoc;// 通过函数 minMaxLoc 定位最匹配的位置cv::minMaxLoc(imgRes, &minVal, &maxVal, &minLoc, &maxLoc, cv::Mat());if (METHOD == CV_TM_SQDIFF || METHOD == CV_TM_SQDIFF_NORMED) {matchLoc = minLoc;} else {matchLoc = maxLoc;}// 将匹配结果用举行框圈出来cv::rectangle(imgDisplay, matchLoc, cv::Point(matchLoc.x + imgTmp.cols, matchLoc.y + imgTmp.rows), cv::Scalar::all(0), 2, 8, 0);cv::rectangle(imgRes, matchLoc, cv::Point(matchLoc.x + imgTmp.cols, matchLoc.y + imgTmp.rows), cv::Scalar::all(0), 2, 8, 0);myQImg = QImage((const unsigned char*)(imgDisplay.data), imgDisplay.cols, imgDisplay.rows, QImage::Format_RGB888);imgShow();
}// 显示图片
void MainWindow::imgShow() {// 在 Qt 界面上显示图片ui->label->setPixmap(QPixmap::fromImage(myQImg.scaled(ui->label->size(), Qt::KeepAspectRatio)));
}void MainWindow::on_pushButton_clicked() {imgproc();
}

2. 人脸识别实例

2.1 mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H#include <QMainWindow>
#include <opencv2/opencv.hpp>#include <vector>
#include <QImage>
#include <QString>
#include <QPixmap>QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACEclass MainWindow : public QMainWindow {Q_OBJECTpublic:MainWindow(QWidget *parent = nullptr);~MainWindow();void initMainWindow();void imgProc();void imgShow();private slots:void on_pushButton_clicked();private:Ui::MainWindow *ui;cv::Mat myImg;QImage myQImg;
};
#endif // MAINWINDOW_H

2.2 mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"MainWindow::MainWindow(QWidget *parent) : QMainWindow(parent), ui(new Ui::MainWindow) {ui->setupUi(this);initMainWindow();
}MainWindow::~MainWindow() {delete ui;
}void MainWindow::initMainWindow() {cv::Mat imgData = cv::imread("D:\\download\\qt_test\\OpencvFace\\model.jpg");cv::cvtColor(imgData, imgData, cv::COLOR_BGR2RGB);myImg = imgData;myQImg = QImage((const unsigned char*)(imgData.data), imgData.cols, imgData.rows, QImage::Format_RGB888);imgShow();
}void MainWindow::imgProc() {cv::CascadeClassifier face_detector;  // 定义人脸识别分类器类cv::CascadeClassifier eyes_detector;  // 定义人眼识别分类器类// 加载视觉识别分类器// 下述两个 xml 文件在 D:\OpenCV-MinGW-Build-OpenCV-3.4.9\etc\haarcascadesface_detector.load("D:\\download\\qt_test\\OpencvFace\\haarcascade_frontalface_alt.xml");eyes_detector.load("D:\\download\\qt_test\\OpencvFace\\haarcascade_eye_tree_eyeglasses.xml");std::vector<cv::Rect> faces;cv::Mat imgSrc = myImg;cv::Mat imgGray;cv::cvtColor(imgSrc, imgGray, cv::COLOR_BGR2GRAY);cv::equalizeHist(imgGray, imgGray);// 多尺寸检测人脸face_detector.detectMultiScale(imgGray, faces, 1.1, 2, 0 | cv::CASCADE_SCALE_IMAGE, cv::Size(30, 30));for (uint64 i = 0; i < faces.size(); i++) {cv::Point center(faces[i].x + faces[i].width * 0.5, faces[i].y + faces[i].height * 0.5);cv::ellipse(imgSrc, center, cv::Size(faces[i].width * 0.5, faces[i].height * 0.5), 0, 0, 360, cv::Scalar(255, 0, 255), 4, 8, 0);cv::Mat faceROI = imgGray(faces[i]);std::vector<cv::Rect> eyes;// 在每张人脸基础上多尺寸检测人眼eyes_detector.detectMultiScale(faceROI, eyes, 1.1, 2, 0 | cv::CASCADE_SCALE_IMAGE, cv::Size(30, 30));for (uint64 j = 0; j < eyes.size(); j++) {cv::Point center(faces[i].x + eyes[j].x + eyes[j].width * 0.5, faces[i].y + eyes[j].y + eyes[j].height * 0.5);int radius = cvRound((eyes[j].width + eyes[j].height) * 0.25);cv::circle(imgSrc, center, radius, cv::Scalar(255, 0, 0), 4, 8, 0);}}cv::Mat imgDst = imgSrc;myQImg = QImage((const unsigned char*)(imgDst.data), imgDst.cols, imgDst.rows, QImage::Format_RGB888);imgShow();
}void MainWindow::imgShow() {ui->label->setScaledContents(true);  // 当图像大于控件大小时，将自动缩放以适应控件的大小// Qt::KeepAspectRatio：保持图像的纵横比例不变ui->label->setPixmap(QPixmap::fromImage(myQImg.scaled(ui->label->size(), Qt::KeepAspectRatio)));
}void MainWindow::on_pushButton_clicked() {imgProc();
}