How to get the extended information about image acquired from TWAIN scanner?

In This Topic

VintaSoft Twain .NET SDK allows to retrieve the extended information about acquired image. The extended image information can contain information about document/page number, image frame, barcodes or patch codes found on a page, information about despeckle, deskew process and more.

You should proceed with the following steps if you want to retrieve the extended information about image that is acquired from TWAIN device:

Check that the retrieving of the extended image information is supported by TWAIN device.
Choose which information you want to retrieve.
Retrieve the extended image information about TWAIN acquired image right after the image is acquired from TWAIN device.

Here is an example that demonstrates how to acquire images from TWAIN device and retrieve from TWAIN device an extended information (document number, page number, camera, frame number, frame, pixel flavor) about acquired images:

static bool _isScanningFinished;



/// <summary>
/// Asynchronously acquires images from TWAIN device and retrieves from TWAIN device an extended information about acquired images.
/// </summary>
public static void AsynchronouslyAcquireImageFromTwainDeviceAndGetExtendedInfoAboutAcquiredImages()
{
    _isScanningFinished = false;

    // create the device manager
    using (Vintasoft.Twain.DeviceManager deviceManager = new Vintasoft.Twain.DeviceManager())
    {
        deviceManager.IsTwain2Compatible = true;
        // open the device manager
        deviceManager.Open();

        // get the device
        Vintasoft.Twain.Device device = deviceManager.DefaultDevice;
        if (device == null)
            return;

        // subscribe to the device events
        device.ImageAcquired += new System.EventHandler<Vintasoft.Twain.ImageAcquiredEventArgs>(device_ImageAcquired);
        device.ScanFinished += new System.EventHandler(device_ScanFinished);

        // set scanning settings
        device.TransferMode = Vintasoft.Twain.TransferMode.Memory;
        device.ShowUI = false;
        device.DisableAfterAcquire = true;

        // open the device
        device.Open();

        // specify that extended information about acquired image is necessary
        device.ExtendedImageInfo.Add(new Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.DocumentNumber));
        device.ExtendedImageInfo.Add(new Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.PageNumber));
        device.ExtendedImageInfo.Add(new Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.Camera));
        device.ExtendedImageInfo.Add(new Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.FrameNumber));
        device.ExtendedImageInfo.Add(new Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.Frame));
        device.ExtendedImageInfo.Add(new Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.PixelFlavor));

        // acquire images asynchronously
        device.Acquire();

        // wait while feeder will be stopped
        while (!_isScanningFinished)
        {
            System.Windows.Forms.Application.DoEvents();
        }
    }
}

/// <summary>
/// Image is acquired.
/// </summary>
private static void device_ImageAcquired(object sender, Vintasoft.Twain.ImageAcquiredEventArgs e)
{
    // output an extended information about the acquired image

    System.Console.WriteLine("IMAGE IS ACQUIRED");
    System.Console.WriteLine();

    Vintasoft.Twain.Device device = (Vintasoft.Twain.Device)sender;
    for (int i = 0; i < device.ExtendedImageInfo.Count; i++)
    {
        AddExtendedImageInfoToResultTextBox(i, device.ExtendedImageInfo[i]);
    }
    System.Console.WriteLine();

    // dispose the acquired image
    e.Image.Dispose();
}

/// <summary>
/// Scan is finished.
/// </summary>
private static void device_ScanFinished(object sender, System.EventArgs e)
{
    Vintasoft.Twain.Device device = (Vintasoft.Twain.Device)sender;

    // unsubscribe from device events
    device.ImageAcquired -= new System.EventHandler<Vintasoft.Twain.ImageAcquiredEventArgs>(device_ImageAcquired);
    device.ScanFinished -= new System.EventHandler(device_ScanFinished);

    // if device is not closed
    if (device.State != Vintasoft.Twain.DeviceState.Closed)
        // close the device
        device.Close();

    System.Console.WriteLine("Scan is finished.");

    _isScanningFinished = true;
}

/// <summary>
/// Add an extended image info to the result text box.
/// </summary>
private static void AddExtendedImageInfoToResultTextBox(int index, Vintasoft.Twain.ExtendedImageInfo info)
{
    if (!info.IsValueValid)
        return;

    System.Console.WriteLine(string.Format("Extended image info {0}", index));
    System.Console.WriteLine(string.Format("  Name={0}", System.Enum.GetName(typeof(Vintasoft.Twain.ExtendedImageInfoId), info.InfoId)));
    System.Console.WriteLine(string.Format("  Id={0}", info.InfoId));
    System.Console.WriteLine(string.Format("  Value type={0}", info.ValueType));

    Vintasoft.Twain.TwainOneValueContainer oneDeviceCapabilityValue = info.Value as Vintasoft.Twain.TwainOneValueContainer;
    if (oneDeviceCapabilityValue != null)
    {
        System.Console.WriteLine(string.Format("  Value={0}", oneDeviceCapabilityValue.Value));
    }
    else
    {
        Vintasoft.Twain.TwainArrayValueContainer arrayDeviceCapabilityValue = info.Value as Vintasoft.Twain.TwainArrayValueContainer;
        if (arrayDeviceCapabilityValue != null)
        {
            string values = "  Values: ";
            if (arrayDeviceCapabilityValue.Values.GetType() == typeof(byte[]))
            {
                values += string.Format("byte[{0}]", arrayDeviceCapabilityValue.Values.Length);
            }
            else
            {
                for (int i = 0; i < arrayDeviceCapabilityValue.Values.Length; i++)
                    values += string.Format("{0}, ", arrayDeviceCapabilityValue.Values.GetValue(i));
            }
            System.Console.WriteLine(values);
        }
    }
}

VB.NET

Shared _isScanningFinished As Boolean



''' <summary>
''' Asynchronously acquires images from TWAIN device and retrieves from TWAIN device an extended information about acquired images.
''' </summary>
Public Shared Sub AsynchronouslyAcquireImageFromTwainDeviceAndGetExtendedInfoAboutAcquiredImages()
    _isScanningFinished = False

    ' create the device manager
    Using deviceManager As New Vintasoft.Twain.DeviceManager()
        deviceManager.IsTwain2Compatible = True
        ' open the device manager
        deviceManager.Open()

        ' get the device
        Dim device As Vintasoft.Twain.Device = deviceManager.DefaultDevice
        If device Is Nothing Then
            Return
        End If

        ' subscribe to the device events
        AddHandler device.ImageAcquired, New System.EventHandler(Of Vintasoft.Twain.ImageAcquiredEventArgs)(AddressOf device_ImageAcquired)
        AddHandler device.ScanFinished, New System.EventHandler(AddressOf device_ScanFinished)

        ' set scanning settings
        device.TransferMode = Vintasoft.Twain.TransferMode.Memory
        device.ShowUI = False
        device.DisableAfterAcquire = True

        ' open the device
        device.Open()

        ' specify that extended information about acquired image is necessary
        device.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.DocumentNumber))
        device.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.PageNumber))
        device.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.Camera))
        device.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.FrameNumber))
        device.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.Frame))
        device.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.PixelFlavor))

        ' acquire images asynchronously
        device.Acquire()

        ' wait while feeder will be stopped
        While Not _isScanningFinished
            System.Windows.Forms.Application.DoEvents()
        End While
    End Using
End Sub

''' <summary>
''' Image is acquired.
''' </summary>
Private Shared Sub device_ImageAcquired(sender As Object, e As Vintasoft.Twain.ImageAcquiredEventArgs)
    ' output an extended information about the acquired image

    System.Console.WriteLine("IMAGE IS ACQUIRED")
    System.Console.WriteLine()

    Dim device As Vintasoft.Twain.Device = DirectCast(sender, Vintasoft.Twain.Device)
    For i As Integer = 0 To device.ExtendedImageInfo.Count - 1
        AddExtendedImageInfoToResultTextBox(i, device.ExtendedImageInfo(i))
    Next
    System.Console.WriteLine()

    ' dispose the acquired image
    e.Image.Dispose()
End Sub

''' <summary>
''' Scan is finished.
''' </summary>
Private Shared Sub device_ScanFinished(sender As Object, e As System.EventArgs)
    Dim device As Vintasoft.Twain.Device = DirectCast(sender, Vintasoft.Twain.Device)

    ' unsubscribe from device events
    RemoveHandler device.ImageAcquired, New System.EventHandler(Of Vintasoft.Twain.ImageAcquiredEventArgs)(AddressOf device_ImageAcquired)
    RemoveHandler device.ScanFinished, New System.EventHandler(AddressOf device_ScanFinished)

    ' if device is not closed
    If device.State <> Vintasoft.Twain.DeviceState.Closed Then
        ' close the device
        device.Close()
    End If

    System.Console.WriteLine("Scan is finished.")

    _isScanningFinished = True
End Sub

''' <summary>
''' Add an extended image info to the result text box.
''' </summary>
Private Shared Sub AddExtendedImageInfoToResultTextBox(index As Integer, info As Vintasoft.Twain.ExtendedImageInfo)
    If Not info.IsValueValid Then
        Return
    End If

    System.Console.WriteLine(String.Format("Extended image info {0}", index))
    System.Console.WriteLine(String.Format("  Name={0}", System.[Enum].GetName(GetType(Vintasoft.Twain.ExtendedImageInfoId), info.InfoId)))
    System.Console.WriteLine(String.Format("  Id={0}", info.InfoId))
    System.Console.WriteLine(String.Format("  Value type={0}", info.ValueType))

    Dim oneDeviceCapabilityValue As Vintasoft.Twain.TwainOneValueContainer = TryCast(info.Value, Vintasoft.Twain.TwainOneValueContainer)
    If oneDeviceCapabilityValue IsNot Nothing Then
        System.Console.WriteLine(String.Format("  Value={0}", oneDeviceCapabilityValue.Value))
    Else
        Dim arrayDeviceCapabilityValue As Vintasoft.Twain.TwainArrayValueContainer = TryCast(info.Value, Vintasoft.Twain.TwainArrayValueContainer)
        If arrayDeviceCapabilityValue IsNot Nothing Then
            Dim values As String = "  Values: "
            If arrayDeviceCapabilityValue.Values.[GetType]() = GetType(Byte()) Then
                values += String.Format("byte[{0}]", arrayDeviceCapabilityValue.Values.Length)
            Else
                For i As Integer = 0 To arrayDeviceCapabilityValue.Values.Length - 1
                    values += String.Format("{0}, ", arrayDeviceCapabilityValue.Values.GetValue(i))
                Next
            End If
            System.Console.WriteLine(values)
        End If
    End If
End Sub

Here is an example that demonstrates how to acquire images from TWAIN device and retrieve from TWAIN device information about barcodes recognized on acquired images:

/// <summary>
/// Synchronously acquires images from TWAIN device and retrieves from TWAIN device information about barcodes recognized on acquired images.
/// </summary>
public void SynchronouslyAcquireImageFromTwainDeviceAndRecognizeBarcodeInAcquiredImages()
{
    using (Vintasoft.Twain.DeviceManager deviceManager = new Vintasoft.Twain.DeviceManager())
    {
        try
        {
            // open the device manager
            deviceManager.Open();

            deviceManager.ShowDefaultDeviceSelectionDialog();

            // get reference to the default device
            Vintasoft.Twain.Device device = deviceManager.DefaultDevice;

            // specify that device UI must not be used
            device.ShowUI = false;
            // specify that device must be closed after scan
            device.DisableAfterAcquire = true;

            // open the device
            device.Open();

            // specify that device should recognize barcodes in acquired images
            device.BarcodeRecognizer.IsEnabled = true;

            // acquire images from device
            Vintasoft.Twain.AcquireModalState acquireModalState = Vintasoft.Twain.AcquireModalState.None;
            do
            {
                acquireModalState = device.AcquireModal();

                switch (acquireModalState)
                {
                    case Vintasoft.Twain.AcquireModalState.ImageAcquired:
                        // get information about recognized barcodes
                        Vintasoft.Twain.TwainBarcodeInfo[] recognizedBarcodes = device.BarcodeRecognizer.GetRecognitionResult();
                        // if barcodes are NOT found
                        if (recognizedBarcodes.Length == 0)
                        {
                            System.Console.WriteLine("Barcodes are NOT found.");
                        }
                        // if barcodes are found
                        else
                        {
                            System.Console.WriteLine(string.Format("{0} barcodes are found.", recognizedBarcodes.Length));
                            // for each recognized barcode
                            for (int i = 0; i < recognizedBarcodes.Length; i++)
                            {
                                // output barcode type
                                System.Console.Write(string.Format("BarcodeType={0} ", recognizedBarcodes[i].Type));
                                // output barcode text
                                System.Console.WriteLine(string.Format("BarcodeText='{0}'", recognizedBarcodes[i].Value));
                            }
                        }

                        // if acquired image is present (Native or Memory transfer mode is used)
                        if (device.AcquiredImage != null)
                            // dispose the acquired image
                            device.AcquiredImage.Dispose();

                        break;
                }
            }
            while (acquireModalState != Vintasoft.Twain.AcquireModalState.None);

            // close the device
            device.Close();

            // close the device manager
            deviceManager.Close();
        }
        catch (Vintasoft.Twain.TwainException ex)
        {
            System.Console.WriteLine("Error: " + ex.Message);
            System.Console.ReadLine();
        }
    }
}

VB.NET

''' <summary>
''' Synchronously acquires images from TWAIN device and retrieves from TWAIN device information about barcodes recognized on acquired images.
''' </summary>
Public Sub SynchronouslyAcquireImageFromTwainDeviceAndRecognizeBarcodeInAcquiredImages()
    Using deviceManager As New Vintasoft.Twain.DeviceManager()
        Try
            ' open the device manager
            deviceManager.Open()

            deviceManager.ShowDefaultDeviceSelectionDialog()

            ' get reference to the default device
            Dim device As Vintasoft.Twain.Device = deviceManager.DefaultDevice

            ' specify that device UI must not be used
            device.ShowUI = False
            ' specify that device must be closed after scan
            device.DisableAfterAcquire = True

            ' open the device
            device.Open()

            ' specify that device should recognize barcodes in acquired images
            device.BarcodeRecognizer.IsEnabled = True

            ' acquire images from device
            Dim acquireModalState As Vintasoft.Twain.AcquireModalState = Vintasoft.Twain.AcquireModalState.None
            Do
                acquireModalState = device.AcquireModal()

                Select Case acquireModalState
                    Case Vintasoft.Twain.AcquireModalState.ImageAcquired
                        ' get information about recognized barcodes
                        Dim recognizedBarcodes As Vintasoft.Twain.TwainBarcodeInfo() = device.BarcodeRecognizer.GetRecognitionResult()
                        ' if barcodes are NOT found
                        If recognizedBarcodes.Length = 0 Then
                            System.Console.WriteLine("Barcodes are NOT found.")
                        Else
                            ' if barcodes are found
                            System.Console.WriteLine(String.Format("{0} barcodes are found.", recognizedBarcodes.Length))
                            ' for each recognized barcode
                            For i As Integer = 0 To recognizedBarcodes.Length - 1
                                ' output barcode type
                                System.Console.Write(String.Format("BarcodeType={0} ", recognizedBarcodes(i).Type))
                                ' output barcode text
                                System.Console.WriteLine(String.Format("BarcodeText='{0}'", recognizedBarcodes(i).Value))
                            Next
                        End If

                        ' if acquired image is present (Native or Memory transfer mode is used)
                        If device.AcquiredImage IsNot Nothing Then
                            ' dispose the acquired image
                            device.AcquiredImage.Dispose()
                        End If

                        Exit Select
                End Select
            Loop While acquireModalState <> Vintasoft.Twain.AcquireModalState.None

            ' close the device
            device.Close()

            ' close the device manager
            deviceManager.Close()
        Catch ex As Vintasoft.Twain.TwainException
            System.Console.WriteLine("Error: " + ex.Message)
            System.Console.ReadLine()
        End Try
    End Using
End Sub

Send Feedback