Mat 到 Bitmap 转换器 - 参数异常

Question

我在 VB Net Forms 应用程序中使用 OpenCVSharp3。我有这个与 C# 一起工作，但现在正在尝试转换为 VB Net。我想将网络摄像头提要显示到图片框。

     ''' <summary>
    ''' Feed from camera
    ''' </summary>
    ''' <remarks></remarks>
    Private _capture As VideoCapture

    ''' <summary>
    ''' Frame from camera
    ''' </summary>
    ''' <remarks></remarks>
    Private _frame As Mat

    ''' <summary>
    ''' Image
    ''' </summary>
    ''' <remarks></remarks>
    Private _image As Bitmap

     Private Sub CaptureCameraCallback()
        Try
            _isCameraRunning = True
            _frame = New Mat()
            _capture = New VideoCapture()
            _capture.Open(_cameraDevice)

            _capture.Read(_frame)

            If _frame IsNot Nothing Then
                While _isCameraRunning
                    _image = BitmapConverter.ToBitmap(_frame)
                    captureFrame.Image = _image
                    _image = Nothing
                End While
            End If
        Catch ex As Exception

        End Try
    End Sub

    Private Sub CaptureCamera()
        _camera = New Thread(AddressOf CaptureCameraCallback)
        _camera.Start()
    End Sub

我有上面的代码可以将网络摄像头提要显示到图片框。但是当我运行它时，我得到以下异常：

A first chance exception of type 'System.ArgumentException' occurred in System.Drawing.dll

异常发生在线路：

_image = BitmapConverter.ToBitmap(_frame)

我想我需要在某个地方进行处理，但不确定这是否是这里的问题。

正在运行的 C# 代码 -

 // Declare required methods
    private void CaptureCamera()
    {
        camera = new Thread(new ThreadStart(CaptureCameraCallback));
        camera.Start();
    }

    private void CaptureCameraCallback()
    {
        try
        {
            frame = new Mat();
            capture = new VideoCapture();
            capture.Open(CameraDevice);
            while (isCameraRunning)
            {
                capture.Read(frame);
                image = BitmapConverter.ToBitmap(frame);
                captureFrame.Image = image;
                image = null;
            }
        }
        catch (Exception)
        {
            MessageBox.Show("No camera found on device", "Start Stream",
            MessageBoxButtons.OK, MessageBoxIcon.Error);
            if (streamBtn.InvokeRequired)
            {
                streamBtn.Invoke(new MethodInvoker(delegate { streamBtn.Text = "Start"; }));
            }
        }
    }

解决方案

''' <summary>
    ''' Get feed from camera
    ''' </summary>
    ''' <remarks></remarks>
    Private Sub CaptureCameraCallback()
        Me._isCameraRunning = True
        Me._frame = New Mat()
        Me._capture = New VideoCapture(_CAMERA_DEVICE)
        Me._capture.Open(_CAMERA_DEVICE)
        ' Enable button if there is a camera feed
        If _isCameraRunning Then
            Me.BeginInvoke(New SetButtonCallback(AddressOf SetButtonStatus), True)
        End If
        While (_isCameraRunning)
            Me._capture.Read(Me._frame)
            Me._image = BitmapConverter.ToBitmap(Me._frame)
            Me.captureFrame.BackgroundImage = Me._image
            Me._image = Nothing
        End While
    End Sub

Answer 1

原代码保证相机是运行

while (isCameraRunning) ...

如果你不想循环，你应该使用一个

If isCameraRunning Then
    _capture.Read(_frame)
    ...
End If

否则您可能会得到无效的帧。也许在尝试读取一个后测试是否有框架也足够了

_capture.Read(_frame)
If _frame IsNot Nothing Then
    ...
End If

如果仍然出现异常，请进行进一步测试以确保框架有效：

_capture.Read(_frame)
If _frame IsNot Nothing AndAlso _frame.Width > 0 AndAlso _frame.Height > 0 Then
    ...
End If

Mat 到 Bitmap 转换器 - 参数异常

Mat to Bitmap converter - Argument Exception

vb.net

opencvsharp