【Qt&OpenCV 图像的感兴趣区域ROI】

图像的ROI(region of interest)是指图像中感兴趣区域。在OpenCV中图像设置图像ROI区域，实现只对ROI区域操作。

文章目录

• 前言
• 一、GUI
• 二、实现代码

• 1、Rubber
• 2、ROI

• 总结

---

前言

越来越多的开发人员选择基于开源的Qt框架与OpenCV来实现界面和算法，其原因不单单是无版权问题，更多是两个社区的发展蓬勃，可用来学习的资料与例程特别丰富。以下是关于利用Qt的rubberBand和OpenCV进行图像的ROI区域获取
软件版本：Qt-5.12.0/OpenCV-4.5.3
平台：Windows10/11–64

---

一、GUI

二、实现代码

1、Rubber

void MainWindow::on_graphicsView_1_rubberBandChanged(const QRect &viewportRect, const QPointF &fromScenePoint, const QPointF &toScenePoint)
{
    rubberFunc(viewportRect, fromScenePoint, toScenePoint);
}
void MainWindow::rubberFunc(const QRect &viewportRect, const QPointF &fromScenePoint, const QPointF &toScenePoint)
{

    size_t numView = ui->tabWidget->currentIndex() % 3;

    QPoint topLeft = viewportRect.topLeft();

    int x1 = topLeft.x();

    double xFromScene = fromScenePoint.x();
    double yFromScene = fromScenePoint.y();
    double xToScene = toScenePoint.x();
    double yToScene = toScenePoint.y();

    if (x1 != 0)
    {
        ui->rubberX1Spin->setValue(static_cast<int>(xFromScene));
        ui->rubberY1Spin->setValue(static_cast<int>(yFromScene));
        ui->rubberX2Spin->setValue(static_cast<int>(xToScene));
        ui->rubberY2Spin->setValue(static_cast<int>(yToScene));
        *tmpMat = dispMat[numView]->clone();
        cv::rectangle(*tmpMat, cv::Point(static_cast<int>(xFromScene), static_cast<int>(yFromScene)), \
                      cv::Point(static_cast<int>(xToScene), \
                                static_cast<int>(yToScene)), \
                      cv::Scalar(0, 0, 255), 1, 1, 0);
    }

    if (tmpMat->channels() == 3)
    {
        QImage tmpImage = QImage(tmpMat->data, tmpMat->cols,tmpMat->rows, \
             static_cast<int>(tmpMat->step), \
             QImage::Format_RGB888);
        dispPixmap[numView]->setPixmap(QPixmap::fromImage(tmpImage.rgbSwapped()));
    }
    else
    {
        QImage tmpImage = QImage(tmpMat->data, tmpMat->cols,tmpMat->rows, \
             static_cast<int>(tmpMat->step), \
             QImage::Format_Grayscale8);
        dispPixmap[numView]->setPixmap(QPixmap::fromImage(tmpImage.rgbSwapped()));
    }
}

2、ROI

void MainWindow::on_maskBtn_clicked()
{
    size_t numView = ui->tabWidget->currentIndex() % 3;

    int x1 = ui->roiX1Spin->value();
    int y1 = ui->roiY1Spin->value();
    int x2 = ui->roiX2Spin->value();
    int y2 = ui->roiY2Spin->value();

    if ((x1 == 0)&&(y1 == 0)&&(x2 == 0)&&(y2 == 0))
    {
        outputInfo(2, tr("Please check the Points."));
        return;
    }

    cv::Rect maskRect(x1, y1, x2 - x1, y2 - y1);
    cv::Mat maskMat = cv::Mat::zeros(dispMat[numView]->size(), \
                                     CV_8UC1);
    tmpMat->zeros(dispMat[numView]->size(), \
                  dispMat[numView]->type());

    maskMat(maskRect).setTo(255);
    dispMat[numView]->copyTo(*tmpMat, maskMat);

    if (ui->roiChkBox->isChecked())
    {
        *dispMat[numView] = tmpMat->clone();
        cvtMatPixmap(dispMat, dispPixmap, numView);
    }
    else
    {
        if (tmpMat->channels() == 3)
        {
            QImage tmpImage = QImage(tmpMat->data, tmpMat->cols,tmpMat->rows, \
                         static_cast<int>(tmpMat->step), \
                         QImage::Format_RGB888);
            dispPixmap[numView]->setPixmap(QPixmap::fromImage(tmpImage.rgbSwapped()));
        }
        else
        {
            QImage tmpImage = QImage(tmpMat->data, tmpMat->cols,tmpMat->rows, \
                         static_cast<int>(tmpMat->step), \
                         QImage::Format_Grayscale8);
            dispPixmap[numView]->setPixmap(QPixmap::fromImage(tmpImage.rgbSwapped()));
        }

    }
    outputInfo(1, tr("Mask done."));
}

void MainWindow::on_roiBtn_clicked()
{
    size_t numView = ui->tabWidget->currentIndex() % 3;

    int x1 = ui->roiX1Spin->value();
    int y1 = ui->roiY1Spin->value();
    int x2 = ui->roiX2Spin->value();
    int y2 = ui->roiY2Spin->value();

    if ((x1 == 0)&&(y1 == 0)&&(x2 == 0)&&(y2 == 0))
    {
        outputInfo(2, tr("Please check the Points."));
        return;
    }

    cv::Rect maskRect(x1, y1, x2 - x1, y2 - y1);
    cv::Mat roiMat = (*dispMat[numView])(maskRect);
    *tmpMat = roiMat.clone();

    if (ui->roiChkBox->isChecked())
    {
        *dispMat[numView] = tmpMat->clone();
        cvtMatPixmap(dispMat, dispPixmap, numView);
    }
    else
    {
        if (tmpMat->channels() == 3)
        {
            QImage tmpImage = QImage(tmpMat->data, tmpMat->cols,tmpMat->rows, \
                         static_cast<int>(tmpMat->step), \
                         QImage::Format_RGB888);
            dispPixmap[numView]->setPixmap(QPixmap::fromImage(tmpImage.rgbSwapped()));
        }
        else
        {
            QImage tmpImage = QImage(tmpMat->data, tmpMat->cols,tmpMat->rows, \
                         static_cast<int>(tmpMat->step), \
                         QImage::Format_Grayscale8);
            dispPixmap[numView]->setPixmap(QPixmap::fromImage(tmpImage.rgbSwapped()));
        }

    }

    outputInfo(1, tr("roiMat done."));

}

---

总结

以上是关于利用Qt进行GUI构建并使用rubberBandChanged进行roi区域获取，或者直接使用OpenCV的roiMat()进行感兴趣区域获取。
参考：
链接:前期其中疑问或错误，欢迎联系交流