Qt + OpenCV 读取并显示图像

一、创建应用&UI

拖拽两个组件：QLable,QPushButton，

写代码并显示图像
.pro文件添加：

INCLUDEPATH += E:\opencv3\opencv\sources\build\install\include\
               E:\opencv3\opencv\sources\build\install\include\opencv2\
               E:\opencv3\opencv\sources\build\install\include\opencv

LIBS += -L E:\opencv3\opencv\sources\build\install\x64\mingw\lib\libopencv_*.a

二、代码与效果演示

mainwindow.cpp

#include <QFileDialog>
#include <QFile>
#include <QMainWindow>
#include <opencv2/opencv.hpp>
#include "mainwindow.h"
#include "ui_mainwindow.h"

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

MainWindow::~MainWindow()
{
    
    
    delete ui;
}

void MainWindow::on_pushButton_clicked()
{
    
    
    QString filename = QFileDialog::getOpenFileName(this,"打开图像","","Image file(*.png *.jpg *.jpeg *.bmp)");
    if(!QFile::exists(filename)){
    
    
        return;
    }
    ui->statusbar->showMessage(filename);
    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->setPixmap(QPixmap::fromImage(img));
    ui->label->resize(ui->label->pixmap()->size());
    filename.clear();
}

这里使用了QImage::QImage (uchar * data, int width, int height, int bytesPerLine, Format format)构造函数，否则可能出现无法正确显示图像的错误（下图右）。

拓展阅读：https://blog.csdn.net/xingchenbingbuyu/article/details/50688378