Qt+OpenCV实现目标检测详解

2022-03-08 09:14:39 作者：SongpingWang

这篇文章主要介绍了如何利用Qt和OpenCV中自带xml文件实现目标检测，文中的实现过程讲解详细，感兴趣的小伙伴可以动手试一试

一、创建项目&UI设计

创建项目，UI设计如下

文件类型判断

简单的判断文件类型

QString file("sample.jpg");
if (file.contains(".jpg") || file.contains(".bmp") || file.contains(".png"))
    qDebug()<<"这是图片。";

推荐使用QMimeDatabase类

QMimeDatabase db;
QMimeType mime = db.mimeTypeForFile("sample.bmp");
if (mime.name().startsWith("image/")) 
    qDebug()<<"这是图片。";

类型	描述	示例
text	普通文本	text/plain, text/html, text/css, text/javascript
image	图像文件(包含动态gif)	image/gif, image/png, image/jpeg, image/bmp, image/webp
audio	音频文件	audio/wav, audio/mpeg, audio/midi, audio/webm, audio/ogg
video	视频文件	video/mp4, video/x-flv, video/webm, video/ogg
application	二进制数据	application/xml, application/pdf

二、代码与演示

mainwindow.h

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
#include <QFileDialog>
#include <QFile>
#include <opencv2/opencv.hpp>
#include <QMainWindow>
#include <QTimer>
#include <QImage>
#include <QPixmap>
#include <QDateTime>
#include <QMutex>
#include <QMutexLocker>
#include <QMimeDatabase>
#include <iostream>

QPixmap Mat2Image(cv::Mat src);

QT_BEGIN_NAMESPACE
namespace Ui { class MainWindow; }
QT_END_NAMESPACE

class MainWindow : public QMainWindow
{
    Q_OBJECT

public:
    MainWindow(QWidget *parent = nullptr);
    void Init();
    ~MainWindow();

private slots:
    void readFrame(); //自定义信号处理函数

    void on_pushButton_OpenFile_clicked();

    void on_pushButton_StartDetect_clicked();

    void on_pushButton_StopDetect_clicked();

    void on_pushButton_FlushDevice_clicked();

private:
    Ui::MainWindow *ui;
    QTimer *timer;
    QImage *img;
    QString mp4_path = NULL;
    cv::VideoCapture *capture;
    cv::CascadeClassifier *classifier;
    std::vector<cv::Rect> bodys;
    int display_HeightWidth = 500;
    int IsDetect_ok = 0;     //用于判断是否加载了MP4和xml
};
#endif // MAINWINDOW_H

mainwindow.cpp

#include "mainwindow.h"
#include "ui_mainwindow.h"


MainWindow::MainWindow(QWidget *parent)
    : QMainWindow(parent)
    , ui(new Ui::MainWindow)
{
    ui->setupUi(this);

    timer = new QTimer(this);
    timer->setInterval(33);
    connect(timer,SIGNAL(timeout()),this,SLOT(readFrame()));
    ui->pushButton_StartDetect->setEnabled(false);
    ui->pushButton_StopDetect->setEnabled(false);
    Init();
}

void MainWindow::Init()
{
    capture = new cv::VideoCapture();
    classifier = new cv::CascadeClassifier;
}

MainWindow::~MainWindow()
{
    capture->release();
    delete ui;
}


void MainWindow::readFrame()
{
    cv::Mat frame, hsv_img, mask_img, gray_src;
    capture->read(frame);
    if (frame.empty()) return;
//    int frame_width = capture->get(cv::CAP_PROP_FRAME_WIDTH);
//    int frame_height = capture->get(cv::CAP_PROP_FRAME_HEIGHT);
//    if (frame_width / frame_height >= 1){
//        cv::resize(frame, frame, cv::Size(display_HeightWidth, (int)(frame_height * display_HeightWidth / frame_width)));
//    }else{
//        cv::resize(frame, frame, cv::Size((int)(frame_width * display_HeightWidth / frame_height), display_HeightWidth));
//    }

    //算法一：行人检测
    cv::cvtColor(frame, gray_src, cv::COLOR_BGR2GRAY);
    cv::equalizeHist(gray_src, gray_src);
    classifier->detectMultiScale(gray_src, bodys, 1.1, 3, 0, cv::Size(30, 30));
    for (size_t i = 0; i < bodys.size(); i++){
        cv::rectangle(frame, bodys[i], cv::Scalar(0, 0, 255), 2, 8, 0);
    }

    //算法二：颜色跟踪
    cv::cvtColor(frame, hsv_img, cv::COLOR_BGR2HSV);
    cv::inRange(hsv_img, cv::Scalar(35, 43, 46), cv::Scalar(155, 255, 255), mask_img);
    cv::Mat kernel = getStructuringElement(cv::MORPH_RECT, cv::Size(3, 3));
    morphologyEx(mask_img, mask_img, cv::MORPH_CLOSE, kernel);
    erode(mask_img, mask_img, kernel);
    GaussianBlur(mask_img, mask_img, cv::Size(3, 3), 0, 0);
    if (cv::waitKey(30) == 27) {
        ui->textEdit_log->setText("Exit...");
        ui->label_raw->clear();
        return;
    }
    cv::cvtColor(frame, frame, cv::COLOR_BGR2RGB);
    QImage rawImage = QImage((uchar*)(frame.data),frame.cols,frame.rows,frame.step,QImage::Format_RGB888);
    ui->label_raw->setPixmap(QPixmap::fromImage(rawImage));     //显示源图像
    QImage dstImage = QImage((uchar*)(mask_img.data),mask_img.cols,mask_img.rows,mask_img.step,QImage::Format_Grayscale8);
    ui->label_detect->setPixmap(QPixmap::fromImage(dstImage));  //显示图像
}


void MainWindow::on_pushButton_OpenFile_clicked()
{
    QString filename = QFileDialog::getOpenFileName(this,"打开文件",".","*.mp4 *.avi;;*.png *.jpg *.jpeg *.bmp");
    if(!QFile::exists(filename)){
        return;
    }
    ui->statusbar->showMessage(filename);
    IsDetect_ok +=1;
    if (IsDetect_ok ==2)
        ui->pushButton_StartDetect->setEnabled(true);
    QMimeDatabase db;
    QMimeType mime = db.mimeTypeForFile(filename);
    if (mime.name().startsWith("image/")) {
        cv::Mat src = cv::imread(filename.toLatin1().data());
        if(src.empty()){
            ui->statusbar->showMessage("图像不存在！");
            return;
        }
        cv::Mat temp;
        if(src.channels()==4)
            cv::cvtColor(src,temp,cv::COLOR_BGRA2RGB);
        else if (src.channels()==3)
            cv::cvtColor(src,temp,cv::COLOR_BGR2RGB);
        else
            cv::cvtColor(src,temp,cv::COLOR_GRAY2RGB);
        QImage img = QImage((uchar*)temp.data,temp.cols,temp.rows,temp.step,QImage::Format_RGB888);
        ui->label_raw->setPixmap(QPixmap::fromImage(img));
        ui->label_raw->resize(ui->label_raw->pixmap()->size());
        filename.clear();
    }else if (mime.name().startsWith("video/")) {
        capture->open(filename.toLatin1().data());
        if (!capture->isOpened()){
            ui->textEdit_log->append("fail to open MP4!");
            return;
        }
        ui->textEdit_log->append(QString::fromUtf8("Open video: %1 succesfully!").arg(filename));

        //获取整个帧数
        long totalFrameNumber = capture->get(CV_CAP_PROP_FRAME_COUNT);
        ui->textEdit_log->append(QString::fromUtf8("整个视频共 %1 帧").arg(totalFrameNumber));
        ui->label_raw->resize(QSize(capture->get(CV_CAP_PROP_FRAME_WIDTH), capture->get(CV_CAP_PROP_FRAME_HEIGHT)));

        //设置开始帧()
        long frameToStart = 0;
        capture->set(CV_CAP_PROP_POS_FRAMES, frameToStart);
        ui->textEdit_log->append(QString::fromUtf8("从第 %1 帧开始读").arg(frameToStart));

        //获取帧率
        double rate = capture->get(CV_CAP_PROP_FPS);
        ui->textEdit_log->append(QString::fromUtf8("帧率为: %1 ").arg(rate));
    }
}

void MainWindow::on_pushButton_StartDetect_clicked()
{
    timer->start();
    ui->pushButton_StartDetect->setEnabled(false);
    ui->pushButton_StopDetect->setEnabled(true);
}

void MainWindow::on_pushButton_StopDetect_clicked()
{
    ui->pushButton_StartDetect->setEnabled(true);
    ui->pushButton_StopDetect->setEnabled(false);
    timer->stop();
}

void MainWindow::on_pushButton_FlushDevice_clicked()
{

    QString xmlfilename = QFileDialog::getOpenFileName(this,"打开文件",".","*.xml");
    if(!QFile::exists(xmlfilename)){
        return;
    }
    ui->statusbar->showMessage(xmlfilename);
    if (!classifier->load(xmlfilename.toLatin1().data())) {
        ui->textEdit_log->append("fail to open classifier_path!");
        return;
    }
    IsDetect_ok +=1;
    ui->textEdit_log->append(QString::fromUtf8("Open xmlfile: %1 succesfully!").arg(xmlfilename));
    if (IsDetect_ok ==2)
        ui->pushButton_StartDetect->setEnabled(true);
}

演示效果

拓展阅读

直接在属性栏目搜索中设置（如下图），或者 pushbutton设置icon和文字

下面是pushbutton设置icon和文字的四种方法详解

1.使用系统自带api

    ui->pushButton->setIconSize(QSize(32,32));
    ui->pushButton->setIcon(QIcon(":/images/Setting.png"));
    ui->pushButton->setText(QString::fromLocal8Bit("系统设置"));
    ui->pushButton->setStyleSheet("QPushButton{border:1px solid blue;background:white;}"
                                  "QPushButton:hover{border:0px;background:blue;}"
                                  "QPushButton:pressed{border:0px;background:red;}");

无法设置icon和文字之间的距离。

2.如果想让icon显示在文字上方可使用QToolButton

ui->toolButton->setIconSize(QSize(32,32));
    ui->toolButton->setIcon(QIcon(":/images/Setting.png"));
    ui->toolButton->setText(QString::fromLocal8Bit("系统设置"));
    ui->toolButton->setToolButtonStyle(Qt::ToolButtonTextUnderIcon);

3.在pushbutton上面使用label进行布局

 QLabel *iconLabel = new QLabel;
    QLabel *textLabel = new QLabel;
    iconLabel->setFixedSize(32,32);
    iconLabel->setStyleSheet("border:1px solid red;");
    textLabel->setStyleSheet("border:1px solid red;");
    iconLabel->setPixmap(QPixmap(":/images/Setting.png"));
    textLabel->setText(QString::fromLocal8Bit("系统设置"));
    textLabel->setFixedWidth(60);
    QHBoxLayout *myLayout = new QHBoxLayout();
    myLayout->addSpacing(10);
    myLayout->addWidget(iconLabel);
    myLayout->addSpacing(30);
    myLayout->addWidget(textLabel);
    myLayout->addStretch();
    ui->pushButton_2->setLayout(myLayout);
    ui->pushButton_2->setStyleSheet("QPushButton{border:1px solid blue;background:white;}"
                                  "QPushButton:hover{border:0px;background:blue;}"
                                  "QPushButton:pressed{border:0px;background:red;}");

4.使用图片，设置stylesheet即可

以上三种方法，需要设置，比较麻烦，最好还是找UI设计按钮图片，这样软件的适配性也比较好。

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Qt+OpenCV实现目标检测详解

一、创建项目&UI设计

二、代码与演示

演示效果

拓展阅读

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