void CAttachImShowDlg::Resize(const std::string strPath, Mat& dst)
{
    CRect rect;
    GetDlgItem(IDC_PIC)->GetClientRect(rect);
    int height = rect.bottom - rect.top;
    int width = rect.right - rect.left;

    Mat src = imread(strPath); //从路径名中读取图片
    resize(src, dst, Size{ width, height }, (0, 0), (0, 0), INTER_LINEAR);//重新调整图像大小
}

BOOL CAttachImShowDlg::AttachMfcWindow()
{
    Mat img;
    Resize("D:\\123.jpg", img);
    namedWindow("Resize");
    HWND hWnd = (HWND)cvGetWindowHandle("Resize");
    if (!hWnd) return FALSE;
    HWND hParent = ::GetParent(hWnd);
    if (!hParent) return FALSE;
    ::ShowWindow(hParent, SW_HIDE);
    ::SetParent(hWnd, GetDlgItem(IDC_PIC)->GetSafeHwnd());
    imshow("Resize", img);
    waitKey(1);
    return TRUE;
}
在OnInitDialog中调用