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 image information:

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

Here is an example that demonstrates how to retrieve the extended information (document number, page number, camera, frame number, frame, pixel flavor) about acquired image:

namespace TwainExamples_CSharp
{
    public partial class How_to_get_extended_information_about_acquired_image : System.Windows.Forms.Form
    {

        /// <summary>
        /// TWAIN device manager.
        /// </summary>
        Vintasoft.Twain.DeviceManager _deviceManager;



        public How_to_get_extended_information_about_acquired_image()
        {
            InitializeComponent();

            // create and open device manager
            _deviceManager = new Vintasoft.Twain.DeviceManager(this);
            _deviceManager.Open();
        }



        /// <summary>
        /// Acquire images asynchronously.
        /// </summary>
        public void AcquireImagesAsynchronously()
        {
            try
            {
                // get reference to the default device
                Vintasoft.Twain.Device device = _deviceManager.DefaultDevice;

                // 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();
            }
            catch (Vintasoft.Twain.TwainException ex)
            {
                System.Windows.Forms.MessageBox.Show(ex.Message);
            }
        }

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

            extendedImageInfoAboutAcquiredImageTextBox.Text += "IMAGE IS ACQUIRED" + System.Environment.NewLine;
            extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;

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

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

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

            extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("Extended image info {0}", index);
            extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;

            extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("  Name={0}", System.Enum.GetName(typeof(Vintasoft.Twain.ExtendedImageInfoId), info.InfoId));
            extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;

            extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("  Id={0}", info.InfoId);
            extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;

            extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("  Value type={0}", info.ValueType);
            extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;

            Vintasoft.Twain.TwainOneValueContainer oneDeviceCapabilityValue = info.Value as Vintasoft.Twain.TwainOneValueContainer;
            if (oneDeviceCapabilityValue != null)
            {
                extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("  Value={0}", oneDeviceCapabilityValue.Value);
                extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;
            }
            else
            {
                Vintasoft.Twain.TwainArrayValueContainer arrayDeviceCapabilityValue = info.Value as Vintasoft.Twain.TwainArrayValueContainer;
                if (arrayDeviceCapabilityValue != null)
                {
                    extendedImageInfoAboutAcquiredImageTextBox.Text += "Values: ";
                    if (arrayDeviceCapabilityValue.Values.GetType() == typeof(byte[]))
                    {
                        extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("byte[{0}]", arrayDeviceCapabilityValue.Values.Length);
                    }
                    else
                    {
                        for (int i = 0; i < arrayDeviceCapabilityValue.Values.Length; i++)
                            extendedImageInfoAboutAcquiredImageTextBox.Text += string.Format("{0}, ", arrayDeviceCapabilityValue.Values.GetValue(i));
                    }
                    extendedImageInfoAboutAcquiredImageTextBox.Text += System.Environment.NewLine;
                }
            }
        }
        
        /// <summary>
        /// Scan is finished.
        /// </summary>
        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.Windows.Forms.MessageBox.Show("Scan is finished.");
        }

    }
}

VB.NET

Partial Public Class How_to_get_extended_information_about_acquired_image
    Inherits Form

    ''' <summary>
    ''' TWAIN device manager.
    ''' </summary>
    Private _deviceManager As Vintasoft.Twain.DeviceManager



    Public Sub New()
        InitializeComponent()

        ' create and open device manager
        _deviceManager = New Vintasoft.Twain.DeviceManager(Me)
        _deviceManager.Open()
    End Sub



    ''' <summary>
    ''' Acquire images asynchronously.
    ''' </summary>
    Public Sub AcquireImagesAsynchronously()
        Try
            ' get reference to the default device
            Dim device1 As Vintasoft.Twain.Device = _deviceManager.DefaultDevice

            ' subscribe to the device events
            AddHandler device1.ImageAcquired, New EventHandler(Of Vintasoft.Twain.ImageAcquiredEventArgs)(AddressOf device_ImageAcquired)
            AddHandler device1.ScanFinished, New EventHandler(AddressOf device_ScanFinished)

            ' set scanning settings
            device1.TransferMode = Vintasoft.Twain.TransferMode.Memory
            device1.ShowUI = False
            device1.DisableAfterAcquire = True

            ' open the device
            device1.Open()

            ' specify that extended information about acquired image is necessary
            device1.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.DocumentNumber))
            device1.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.PageNumber))
            device1.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.Camera))
            device1.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.FrameNumber))
            device1.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.Frame))
            device1.ExtendedImageInfo.Add(New Vintasoft.Twain.ExtendedImageInfo(Vintasoft.Twain.ExtendedImageInfoId.PixelFlavor))

            ' acquire images asynchronously
            device1.Acquire()
        Catch ex As Vintasoft.Twain.TwainException
            MessageBox.Show(ex.Message)
        End Try
    End Sub

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

        extendedImageInfoAboutAcquiredImageTextBox.Text += "IMAGE IS ACQUIRED" + Environment.NewLine
        extendedImageInfoAboutAcquiredImageTextBox.Text += Environment.NewLine

        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
        extendedImageInfoAboutAcquiredImageTextBox.Text += Environment.NewLine

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

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

        extendedImageInfoAboutAcquiredImageTextBox.Text += String.Format("Extended image info {0}", index)
        extendedImageInfoAboutAcquiredImageTextBox.Text += Environment.NewLine

        extendedImageInfoAboutAcquiredImageTextBox.Text += String.Format("  Name={0}", [Enum].GetName(GetType(Vintasoft.Twain.ExtendedImageInfoId), info.InfoId))
        extendedImageInfoAboutAcquiredImageTextBox.Text += Environment.NewLine

        extendedImageInfoAboutAcquiredImageTextBox.Text += String.Format("  Id={0}", info.InfoId)
        extendedImageInfoAboutAcquiredImageTextBox.Text += Environment.NewLine

        extendedImageInfoAboutAcquiredImageTextBox.Text += String.Format("  Value type={0}", info.ValueType)
        extendedImageInfoAboutAcquiredImageTextBox.Text += Environment.NewLine

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

    ''' <summary>
    ''' Scan is finished.
    ''' </summary>
    Private Sub device_ScanFinished(ByVal sender As Object, ByVal e As EventArgs)
        Dim device1 As Vintasoft.Twain.Device = DirectCast(sender, Vintasoft.Twain.Device)

        ' unsubscribe from device events
        RemoveHandler device1.ImageAcquired, New EventHandler(Of Vintasoft.Twain.ImageAcquiredEventArgs)(AddressOf device_ImageAcquired)
        RemoveHandler device1.ScanFinished, New EventHandler(AddressOf device_ScanFinished)

        ' if device is not closed
        If device1.State <> Vintasoft.Twain.DeviceState.Closed Then
            ' close the device
            device1.Close()
        End If

        MessageBox.Show("Scan is finished.")
    End Sub

End Class

Here is an example that demonstrates how to get information about barcodes recognized on acquired image:

public void GetExtendedImageInfo()
{
    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

Public Sub GetExtendedImageInfo()
    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__1 As Vintasoft.Twain.AcquireModalState = Vintasoft.Twain.AcquireModalState.None
            Do
                acquireModalState__1 = device.AcquireModal()

                Select Case acquireModalState__1
                    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
                            Console.WriteLine("Barcodes are NOT found.")
                            ' if barcodes are found
                        Else
                            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
                                Console.Write(String.Format("BarcodeType={0} ", recognizedBarcodes(i).Type))
                                ' output barcode text
                                Console.WriteLine(String.Format("BarcodeText='{0}'", recognizedBarcodes(i).Value))
                            Next i
                        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__1 <> Vintasoft.Twain.AcquireModalState.None

            ' close the device
            device.Close()

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

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