VisualBasic.NET的OpenCvSharp4机器视觉编程简单应用

在.NET下常用OpenCV进行图像处理工作，而常用的OpenCV库有Emgu CV和OpenCvSharp。OpenCvSharp使用习惯比EmguCV更接近原始的OpenCV，有详细的使用样例供参考。因此在网上收集了一些OpenCV的应用。

准备工作

打开VS，创建VB.NET的Winform项目。NuGet安装OpenCvSharp4的两个包。

在Form中引用

Imports OpenCvSharp

轮廓

vb.net2019- 调用 opencv_AI_LX的博客-CSDN博客_opencv vb

Private Sub showPict(ByVal fileName As String)
    ' Dim src As Mat = New Mat(fileName, ImreadModes.Grayscale)
    Dim src As Mat = Cv2.ImRead(fileName, ImreadModes.Grayscale)
    Dim dst As Mat = New Mat()

    Cv2.Canny(src, dst, 50, 100)
    Using (New Window("src image", src))
        Using (New Window("dst image", dst))
            Cv2.WaitKey()
        End Using
    End Using

End Sub
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
    OpenFileDialog1.Filter = "Image Files(*.BMP;*.JPG;*.GIF;*.PNG)|*.BMP;*.JPG;*.GIF;*.PNG"
    Dim fResult = OpenFileDialog1.ShowDialog() '打开文件选择框
    If fResult = DialogResult.OK Then
        Dim fileName As String = OpenFileDialog1.FileName '得到选择的文件
        showPict(fileName)
    End If
End Sub

调用本地摄像头

c# OpenCvSharp调用电脑本机摄像头 – 蒋智昊的博客 (chanpinxue.cn)

Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
    ' 定义图像捕捉方式 从摄像头 ， 注意 Windows下需要选择 VideoCaptureAPIs.DSHOW
    Dim capture = New VideoCapture(0, VideoCaptureAPIs.DSHOW)
    If Not capture.IsOpened() Then Return
    capture.XI_OffsetX = 0 '以左上角为起点 坐标X
    capture.XI_OffsetY = 0 '以左上角为起点 坐标Y
    capture.FrameWidth = 640 '宽
    capture.FrameHeight = 480 '高 
    capture.AutoFocus = True
    Const sleepTime As Integer = 10
    Dim window = New Window("cv")

    'Mat作为图像的存储容器
    Dim image = New Mat()

    While True
        capture.Read(image)
        If image.Empty() Then Exit While
        window.ShowImage(image)
        'Windows窗体PictureBox加载
        'picboxDest.Image = image.ToBitmap()

        Dim flag As Integer = Cv2.WaitKey(sleepTime)

        If flag >= 0 Then
            Exit While
        End If

        Application.DoEvents()
    End While
End Sub

面部识别

「图像处理」OpenCVSharp 调用摄像头及人脸识别_Raink_LH的博客-CSDN博客_opencvsharp虚拟摄像头

Private Sub Button3_Click(sender As Object, e As EventArgs) Handles Button3.Click
    Dim video As FrameSource = Cv2.CreateFrameSource_Camera(0)
    Cv2.NamedWindow("video")

    While True
        Dim frame As Mat = New Mat()
        video.NextFrame(frame)
        Dim faceFinder As OpenCvSharp.CascadeClassifier = New CascadeClassifier("E:桌面SamplesEasyPR-masteropencv2datahaarcascadeshaarcascade_frontalface_default.xml")
        Dim eyeFinder As OpenCvSharp.CascadeClassifier = New CascadeClassifier("E:桌面SamplesEasyPR-masteropencv2datahaarcascadeshaarcascade_eye_tree_eyeglasses.xml")
        Dim faceRects As Rect() = faceFinder.DetectMultiScale(frame)
        Dim eyeRects As Rect() = eyeFinder.DetectMultiScale(frame)

        If faceRects.Length > 0 Then
            Cv2.Rectangle(frame, faceRects(0), New Scalar(0, 0, 255), 3)
        End If

        If eyeRects.Length > 1 Then
            Cv2.Rectangle(frame, eyeRects(0), New Scalar(255, 0, 0), 3)
            Cv2.Rectangle(frame, eyeRects(1), New Scalar(255, 0, 0), 3)
        End If

        Cv2.ImShow("video", frame)
        Cv2.WaitKey(1)
    End While
End Sub

对代码中的几个点做说明：

主要是检测到的人脸进行框出，并且实时显示

“E:桌面SamplesEasyPR-masteropencv2datahaarcascadeshaarcascade_frontalface_default.xml” 和

“E:桌面SamplesEasyPR-masteropencv2datahaarcascadeshaarcascade_eye_tree_eyeglasses.xml”

两个文件，这两个文件来自于Opencv(官方C 库),需要下载安装Opencv，在如上的的相应目录去找（我的安装在”E:桌面SamplesEasyPR-masteropencv2″目录）。

光流法检测图像位移及标注

基于opencvsharp的图像位移检测及相似点标注（光流金字塔法）_salt_bean_curd的博客-CSDN博客

    ''' 

    ''' 光流法，拼接两张图片
    ''' 
    ''' 第一张图片
    ''' 第二张图片
    ''' 
    Private Function MM(PrevimgColo As Mat, NextimgColo As Mat) As Mat

        Dim previmg As Mat = New Mat()
        Dim nextimg As Mat = New Mat()
        Cv2.CvtColor(PrevimgColo, previmg, ColorConversionCodes.BGR2GRAY)
        Cv2.CvtColor(NextimgColo, nextimg, ColorConversionCodes.BGR2GRAY)
        '特征点检测（角、点）
        Const MAX_Count As Integer = 500
        Const Win_size As Integer = 10
        '像素级检测特征点
        Dim points1 As Point2f()
        points1 = Cv2.GoodFeaturesToTrack(previmg, MAX_Count, 0.01, 5, New Mat(), 3, False, 0.04)
        '亚像素级检测
        Dim points1Sub As Point2f()
        points1Sub = Cv2.CornerSubPix(previmg, points1, New Size(Win_size, Win_size), New Size(-1, -1), New TermCriteria())
        '迭代控制
        Dim criteria As TermCriteria = New TermCriteria(CriteriaTypes.Eps And CriteriaTypes.Count, 20, 0.03)
        '光流金字塔，输出图二的特征点
        Dim status As Byte()
        Dim err As Single()
        Dim points2 As Point2f() = New Point2f(points1Sub.Length - 1) {}
        Cv2.CalcOpticalFlowPyrLK(previmg, nextimg, points1Sub, points2, status, err)
#Region "输出偏移量，两图像拼接，可视化结果"
        Dim Coll As Mat() = New Mat(1) {}
        Coll(0) = PrevimgColo
        Coll(1) = NextimgColo
        Dim mergeImg As Mat = New Mat()
        Cv2.HConcat(Coll, mergeImg)
        Dim points_temp As Point2f() = points2
        Dim blue As Scalar = Scalar.Blue

        For num As Integer = 0 To points1Sub.Length - 1
            If status(num) = 1 Then
                points_temp(num).X  = PrevimgColo.Width
                Cv2.Line(mergeImg, CType(points1Sub(num), Point), CType(points_temp(num), Point), blue, 1, LineTypes.AntiAlias)
            End If
        Next
#End Region
        Return mergeImg
    End Function

    ''' 

    ''' 光流法，在一张图片上显示
    ''' 
    ''' 第一张图片
    ''' 第二张图片
    ''' 
    Private Function MM1(PrevimgColo As Mat, NextimgColo As Mat) As Mat

        Dim previmg As Mat = New Mat()
        Dim nextimg As Mat = New Mat()
        Cv2.CvtColor(PrevimgColo, previmg, ColorConversionCodes.BGR2GRAY)
        Cv2.CvtColor(NextimgColo, nextimg, ColorConversionCodes.BGR2GRAY)
        '特征点检测（角、点）
        Const MAX_Count As Integer = 500
        Const Win_size As Integer = 10
        '像素级检测特征点
        Dim points1 As Point2f()
        points1 = Cv2.GoodFeaturesToTrack(previmg, MAX_Count, 0.01, 5, New Mat(), 3, False, 0.04)
        '亚像素级检测
        Dim points1Sub As Point2f()
        points1Sub = Cv2.CornerSubPix(previmg, points1, New Size(Win_size, Win_size), New Size(-1, -1), New TermCriteria())
        '迭代控制
        Dim criteria As TermCriteria = New TermCriteria(CriteriaTypes.Eps And CriteriaTypes.Count, 20, 0.03)
        '光流金字塔，输出图二的特征点
        Dim status As Byte()
        Dim err As Single()
        Dim points2 As Point2f() = New Point2f(points1Sub.Length - 1) {}
        Cv2.CalcOpticalFlowPyrLK(previmg, nextimg, points1Sub, points2, status, err)
#Region "输出偏移量，可视化结果"
        Dim mergeImg As Mat = NextimgColo
        Dim blue As Scalar = Scalar.Blue
        Debug.Print("===========")
        For num As Integer = 0 To points1Sub.Length - 1
            If status(num) = 1 Then
                Cv2.Line(mergeImg, CType(points1Sub(num), Point), CType(points2(num), Point), blue, 1, LineTypes.AntiAlias)
                DistanceBetween(points1Sub(num).X, points1Sub(num).Y, points2(num).X, points2(num).Y)
            End If
        Next
#End Region
        Return mergeImg
    End Function
    Public Function DistanceBetween(ByVal X1 As Single, ByVal Y1 As Single, ByVal X2 As Single, ByVal Y2 As Single) As Single
        ' Calculate the distance between two points, given their X/Y coordinates. 
        ' The short version...
        DistanceBetween = Math.Sqrt((Math.Abs(X2 - X1) ^ 2)   (Math.Abs(Y2 - Y1) ^ 2))
        ' The longer version, to illustrate how it works...
        Dim Horizontal As Single, Vertical As Single
        Horizontal = Math.Abs(X2 - X1)
        Vertical = Math.Abs(Y2 - Y1)
        DistanceBetween = Math.Sqrt((Horizontal * Horizontal)   (Vertical * Vertical))
        If DistanceBetween > 2 Then
            Debug.Print(Format(DistanceBetween, "#00.00") & vbTab & Format(X1 - X2, "#00.00") & vbTab & Format(Y1 - Y2, "#00.00"))
        End If
    End Function

    Private Sub Button4_Click(sender As Object, e As EventArgs) Handles Button4.Click
        Dim video As FrameSource = Cv2.CreateFrameSource_Camera(0)
        Cv2.NamedWindow("video")

        While True
            Dim frame0 As Mat = New Mat()
            video.NextFrame(frame0)
            Dim flag As Integer = Cv2.WaitKey(1000)

            If flag >= 0 Then
                Exit While
            End If

            Dim frame1 As Mat = New Mat()
            video.NextFrame(frame1)

            Cv2.ImShow("video", MM1(frame0, frame1))
            Cv2.WaitKey(1)
        End While

    End Sub

MM:

MM1:

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