Qt调用 OpenCV 显示图片

作者：billy
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前言

上一章节介绍了如何使用 VS2017 和 Qt 来编译 OpenCV，具体请参考：使用VS2017和Qt编译OpenCV库，编译完成之后就可以应用了。

OpenCV 3.0 以后，图像采用Mat格式进行存储，而Qt中图像存储采用的是QImage类，因此如果需要在Qt中显示 OpenCV 处理过程中的图像，需要将Mat类对象转换为QImage类对象。Mat格式采用BGR的存储顺序，而QImage类采用的是RGB存储顺序，因此需要将存储格式从 BGR 转换成 RGB。完成转换后，在Qt界面中显示QImage类对象，可以采用 QLabel 或者 QGraphicsView。

注意：OpenCV 4.0 仅支持x64，所以编译器需要选用 arm64，否则链接库时会失败；

导入库文件

QT       += core gui

greaterThan(QT_MAJOR_VERSION, 4): QT += widgets

CONFIG += c++11 debug_and_release

# The following define makes your compiler emit warnings if you use
# any Qt feature that has been marked deprecated (the exact warnings
# depend on your compiler). Please consult the documentation of the
# deprecated API in order to know how to port your code away from it.
DEFINES += QT_DEPRECATED_WARNINGS

# You can also make your code fail to compile if it uses deprecated APIs.
# In order to do so, uncomment the following line.
# You can also select to disable deprecated APIs only up to a certain version of Qt.
#DEFINES += QT_DISABLE_DEPRECATED_BEFORE=0x060000    # disables all the APIs deprecated before Qt 6.0.0

SOURCES += \
    main.cpp \
    mainwindow.cpp

HEADERS += \
    mainwindow.h

FORMS += \
    mainwindow.ui

# Default rules for deployment.
qnx: target.path = /tmp/$${TARGET}/bin
else: unix:!android: target.path = /opt/$${TARGET}/bin
!isEmpty(target.path): INSTALLS += target

INCLUDEPATH += $$PWD/OpenCV_msvc2017_64/include
DEPENDPATH += $$PWD/OpenCV_msvc2017_64/include

windows {
    CONFIG(debug, debug|release) {
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_calib3d420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_core420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_dnn420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_features2d420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_flann420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_gapi420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_highgui420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_imgcodecs420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_imgproc420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_ml420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_objdetect420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_photo420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_stitching420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_video420d
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/debug/ -lopencv_videoio420d
    } else {
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_calib3d420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_core420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_dnn420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_features2d420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_flann420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_gapi420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_highgui420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_imgcodecs420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_imgproc420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_ml420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_objdetect420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_photo420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_stitching420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_video420
        LIBS += -L$$PWD/OpenCV_msvc2017_64/lib/release/ -lopencv_videoio420
    }
}

显示图片

#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <opencv2/opencv.hpp>
using namespace cv;

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

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

void MainWindow::on_showBtn_clicked()
{
    QString page_1 = "D:/Qt/MWD/MyOpenCVDemo/1.jpg";
    QString page_2 = "D:/Qt/MWD/MyOpenCVDemo/2.jpg";

    Mat srcImage_1 = imread(page_1.toLatin1().data());      // 读取图片数据
    Mat srcImage_2 = imread(page_2.toLatin1().data());

    cvtColor(srcImage_1, srcImage_1, COLOR_BGR2RGB);        // 图像格式转换
    cvtColor(srcImage_2, srcImage_2, COLOR_BGR2RGB);

    QImage disImage_1 = QImage((const unsigned char*)(srcImage_1.data), srcImage_1.cols, srcImage_1.rows, QImage::Format_RGB888);
    QImage disImage_2 = QImage((const unsigned char*)(srcImage_2.data), srcImage_2.cols, srcImage_2.rows, QImage::Format_RGB888);

    ui->label->setPixmap(QPixmap::fromImage(disImage_1.scaled(ui->label->size(), Qt::KeepAspectRatio)));  // label 显示图像

    QGraphicsScene *scene = new QGraphicsScene;             // graphicsView 显示图像
    scene->addPixmap(QPixmap::fromImage(disImage_2));
    ui->graphicsView->setScene(scene);
    ui->graphicsView->show();
}

运行结果：