Scan to Searchable PDF

Take the following steps to create and run a program that shows how scan a document and convert it to a searchable PDF file.

  1. Start Visual Studio

  2. Choose File->New->Project from the menu

  3. In the New Project dialog box, choose either "Visual C# Projects" or "VB Projects" in the Projects Type List, and choose "Windows Application" in Visual Studio 2005 or "Windows Forms Application" in Visual Studio 2008 from the Templates List

  4. Type the project name as "OcrTutorial3" in the Project Name field, and then choose OK. If desired, type a new location for your project or select a directory using the Browse button, and then choose OK.

  5. In the "Solution Explorer" window, right-click on the "References" folder, and select "Add Reference..." from the context menu. In the "Add Reference" dialog box, select the ".NET" tab and browse to LEADTOOLS For .NET "<LEADTOOLS_INSTALLDIR>\Bin\DotNet\Win32" folder and select the following DLLs:

    • Leadtools.dll
    • Leadtools.Codecs.dll
    • Leadtools.Forms.dll
    • Leadtools.Forms.DocumentWriters.dll
    • Leadtools.Forms.Ocr.dll
    • Leadtools.Forms.Ocr.Professional.dll
    • Leadtools.Twain.dll
    • Leadtools.ImageProcessing.Core.dll
    • Leadtools.Codecs.Bmp.dll
    • Leadtools.Codecs.Cmp.dll
    • Leadtools.Codecs.Tif.dll
    • Leadtools.Codecs.Fax.dll

    Note: The Leadtools.Codecs.*.dll references added are for the BMP, JPG, CMP, TIF and FAX image file formats. Add any additional file format codec DLL if required in your application.

  6. Drag and drop three buttons in Form1. Leave all the buttons names as the default "button1, button2 ...", then change the Text property of each button to the following:

    ButtonTextbutton1Change output directorybutton2Select the Scannerbutton3Scan and OCR

  7. Switch to Form1 code view (Right-click Form1 in the solution explorer then select View Code) and add the following lines at the beginning of the file after any Importsor usingsection if there are any:

    C#
    VB
    Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Twain 
Imports Leadtools.Forms 
Imports Leadtools.Forms.DocumentWriters 
Imports Leadtools.Forms.Ocr 
Imports Leadtools.ImageProcessing.Core 
                 
     
    using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Twain; 
using Leadtools.Forms; 
using Leadtools.Forms.DocumentWriters; 
using Leadtools.Forms.Ocr; 
using Leadtools.ImageProcessing.Core;

  8. Add the following private variables to the Form1 class:

    C#
    VB
    ' The OCR engine instance 
Private _ocrEngine As IOcrEngine 
' The OCR document 
Private _ocrDocument As IOcrDocument 
' The Twain session 
Private _twainSession As TwainSession 
' The output directory for saving PDF files 
Private _outputDirectory As String = "C:\MyImages" 
' The image processing commands we are going to use to clean the scanned image 
Private deskewCmd As DeskewCommand 
Private despeckleCmd As DespeckleCommand 
Private dotRemoveCmd As DotRemoveCommand 
Private holePunchRemoveCmd As HolePunchRemoveCommand 
Private lineRemoveCmd As LineRemoveCommand 
                 
     
    // The OCR engine instance 
private IOcrEngine _ocrEngine; 
// The OCR document 
private IOcrDocument _ocrDocument; 
// The Twain session 
private TwainSession _twainSession; 
// The output directory for saving PDF files 
private string _outputDirectory = @"C:\MyImages"; 
// The image processing commands we are going to use to clean the scanned image 
private DeskewCommand deskewCmd; 
private DespeckleCommand despeckleCmd; 
private DotRemoveCommand dotRemoveCmd; 
private HolePunchRemoveCommand holePunchRemoveCmd; 
private LineRemoveCommand lineRemoveCmd;

  9. Add the following code to the Form1 constructor (in VB, you can copy/paste the whole Sub New code from here):

    C#
    VB
    Sub New() 
   ' This call is required by the Windows Form Designer. 
   InitializeComponent() 
   ' Add any initialization after the InitializeComponent() call. 
   Dim MY_LICENSE_FILE As String = "d:\temp\TestLic.lic" 
   ' Unlock the OCR support 
   Dim MY_OCRPRODEVELOPER_KEY As String = "xyz123abc" 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_OCRPRODEVELOPER_KEY) 
   ' Unlock the PDF save support 
   Dim MY_OCRPDFDEVELOPER_KEY As String = "abc123xyz" 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_OCRPDFDEVELOPER_KEY) 
   ' Unlock Document support 
   Dim MY_DOCDEVELOPER_KEY As String = "123xyzabc" 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_DOCDEVELOPER_KEY) 
   ' Initialize the OCR engine 
   _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, False) 
   ' Startup the engine 
   _ocrEngine.Startup(Nothing, Nothing, Nothing, "C:\LEADTOOLS 19\Bin\Common\OcrAdvantageRuntime") 
   ' Create the OCR document 
   _ocrDocument = _ocrEngine.DocumentManager.CreateDocument() 
   ' Initalize Twain scanning session 
   _twainSession = New TwainSession() 
   _twainSession.Startup(Me, "My Company", "My Product", "My Version", "My Application", TwainStartupFlags.None) 
   ' Subscribe to the TwainSession.Acquire event to get the image 
   AddHandler _twainSession.AcquirePage, AddressOf _twainSession_AcquirePage 
   ' Initialize the image processing commands we are going to use 
   ' Initialize Deskew 
   deskewCmd = New DeskewCommand() 
   ' Initialize Despeckle 
   despeckleCmd = New DespeckleCommand() 
   ' Initialize DotRemove 
   dotRemoveCmd = New DotRemoveCommand() 
   dotRemoveCmd.Flags = _ 
      DotRemoveCommandFlags.UseDiagonals Or _ 
      DotRemoveCommandFlags.UseSize 
   dotRemoveCmd.MaximumDotHeight = 8 
   dotRemoveCmd.MaximumDotWidth = 8 
   dotRemoveCmd.MinimumDotHeight = 2 
   dotRemoveCmd.MinimumDotWidth = 2 
   ' Initialize HolePunchRemove 
   holePunchRemoveCmd = New HolePunchRemoveCommand() 
   holePunchRemoveCmd.Flags = _ 
      HolePunchRemoveCommandFlags.UseDpi Or _ 
      HolePunchRemoveCommandFlags.UseCount Or _ 
      HolePunchRemoveCommandFlags.UseLocation 
   holePunchRemoveCmd.Location = HolePunchRemoveCommandLocation.Left 
   ' Initialize LineRemove 
   lineRemoveCmd = New LineRemoveCommand() 
   lineRemoveCmd.MaximumLineWidth = 9 
   lineRemoveCmd.MinimumLineLength = 400 
   lineRemoveCmd.Wall = 15 
   lineRemoveCmd.MaximumWallPercent = 10 
   lineRemoveCmd.Variance = 3 
   lineRemoveCmd.GapLength = 3 
End Sub 
                 
     
    public Form1() 
{ 
   InitializeComponent(); 
   // Unlock the OCR support 
   string MY_LICENSE_FILE = "d:\\temp\\TestLic.lic"; 
   string MY_OCRPRODEVELOPER_KEY = "xyz123abc"; 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_OCRPRODEVELOPER_KEY); 
   // Unlock the PDF save support 
   string MY_OCRPDFDEVELOPER_KEY = "abc123xyz"; 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_OCRPDFDEVELOPER_KEY); 
   // Unlock Document support 
   string MY_DOCDEVELOPER_KEY = "123xyzabc"; 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_DOCDEVELOPER_KEY); 
   // Initialize the OCR engine 
   _ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false); 
   // Startup the engine 
   _ocrEngine.Startup(null, null, null, @"C:\LEADTOOLS 19\Bin\Common\OcrAdvantageRuntime"); 
   // Create the OCR document 
   _ocrDocument = _ocrEngine.DocumentManager.CreateDocument(); 
   // Initalize Twain scanning session 
   _twainSession = new TwainSession(); 
   _twainSession.Startup(this, "My Company", "My Product", "My Version", "My Application", TwainStartupFlags.None); 
   // Subscribe to the TwainSession.Acquire event to get the image 
   _twainSession.AcquirePage += new EventHandler<TwainAcquirePageEventArgs>(_twainSession_AcquirePage); 
   // Initialize the image processing commands we are going to use 
   // Initialize Deskew 
   deskewCmd = new DeskewCommand(); 
   // Initialize Despeckle 
   despeckleCmd = new DespeckleCommand(); 
   // Initialize DotRemove 
   dotRemoveCmd = new DotRemoveCommand(); 
   dotRemoveCmd.Flags = 
      DotRemoveCommandFlags.UseDiagonals | 
      DotRemoveCommandFlags.UseSize; 
   dotRemoveCmd.MaximumDotHeight = 8; 
   dotRemoveCmd.MaximumDotWidth = 8; 
   dotRemoveCmd.MinimumDotHeight = 2; 
   dotRemoveCmd.MinimumDotWidth = 2; 
    // Initialize HolePunchRemove 
   holePunchRemoveCmd = new HolePunchRemoveCommand(); 
   holePunchRemoveCmd.Flags = 
      HolePunchRemoveCommandFlags.UseDpi | 
      HolePunchRemoveCommandFlags.UseCount | 
      HolePunchRemoveCommandFlags.UseLocation; 
   holePunchRemoveCmd.Location = HolePunchRemoveCommandLocation.Left; 
   // Initialize LineRemove 
   lineRemoveCmd = new LineRemoveCommand(); 
   lineRemoveCmd.MaximumLineWidth = 9; 
   lineRemoveCmd.MinimumLineLength = 400; 
   lineRemoveCmd.Wall = 15; 
   lineRemoveCmd.MaximumWallPercent = 10; 
   lineRemoveCmd.Variance = 3; 
   lineRemoveCmd.GapLength = 3; 
}

  10. Override the Form1 closed event to add the code necessary to shutdown the OCR engine when the application terminates:

    C#
    VB
    Protected Overrides Sub OnFormClosed(ByVal e As FormClosedEventArgs) 
   ' Destroy the OCR document 
   _ocrDocument.Dispose() 
   ' Shutdown and dispose the OCR engine 
   _ocrEngine.Dispose() 
   ' Close the Twain session 
   _twainSession.Shutdown() 
   MyBase.OnFormClosed(e) 
End Sub 
                 
     
    protected override void OnFormClosed(FormClosedEventArgs e) 
{ 
   // Destroy the OCR document 
   _ocrDocument.Dispose(); 
   // Shutdown and dispose the OCR engine 
   _ocrEngine.Dispose(); 
   // Close the Twain session 
   _twainSession.Shutdown(); 
   base.OnFormClosed(e); 
}

  11. Add the following code for the button1 (Change output directory) control’s Clickhandler:

    C#
    VB
    Private Sub button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button1.Click 
   ' Change the output directory 
   Dim dlg As New FolderBrowserDialog() 
   dlg.SelectedPath = _outputDirectory 
   dlg.ShowNewFolderButton = True 
   If (dlg.ShowDialog(Me) = DialogResult.OK) Then 
      _outputDirectory = System.IO.Path.GetFullPath(dlg.SelectedPath) 
   End If 
End Sub 
                 
     
    private void button1_Click(object sender, EventArgs e) 
{ 
   // Change the output directory 
   FolderBrowserDialog dlg = new FolderBrowserDialog(); 
   dlg.SelectedPath = _outputDirectory; 
   dlg.ShowNewFolderButton = true; 
   if(dlg.ShowDialog(this) == DialogResult.OK) 
      _outputDirectory = System.IO.Path.GetFullPath(dlg.SelectedPath); 
}

  12. Add the following code for the button2 (Select the Scanner) control’s Clickhandler:

    C#
    VB
    Private Sub button2_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button2.Click 
   ' Select the scanner to use 
   _twainSession.SelectSource(Nothing) 
End Sub 
                 
     
    private void button2_Click(object sender, EventArgs e) 
{ 
   // Select the scanner to use 
   _twainSession.SelectSource(null); 
}

  13. Add the following code for the button3 (Scan and OCR) control’s Clickhandler:

    C#
    VB
    Private Sub button3_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles button3.Click 
   ' Create the output directory if it does not exist 
   If (Not System.IO.Directory.Exists(_outputDirectory)) Then 
      System.IO.Directory.CreateDirectory(_outputDirectory) 
   End If 
   ' Build the output PDF file name 
   Dim pdfFileName As String = System.IO.Path.Combine(_outputDirectory, "Scanned.pdf") 
   ' First remove all the pages added to the OCR document 
   _ocrDocument.Pages.Clear() 
   ' Scan the new page(s) 
   _twainSession.Acquire(TwainUserInterfaceFlags.Show) 
   ' The pages should be added to the OCR document now. 
   ' Recognize and save as PDF 
   _ocrDocument.Pages.Recognize(Nothing) 
   _ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, Nothing) 
   ' Show the result PDF file 
   System.Diagnostics.Process.Start(pdfFileName) 
End Sub 
                 
     
    private void button3_Click(object sender, EventArgs e) 
{ 
   // Create the output directory if it does not exist 
   if(!System.IO.Directory.Exists(_outputDirectory)) 
      System.IO.Directory.CreateDirectory(_outputDirectory); 
   // Build the output PDF file name 
   string pdfFileName = System.IO.Path.Combine(_outputDirectory, "Scanned.pdf"); 
   // First remove all the pages added to the OCR document 
   _ocrDocument.Pages.Clear(); 
   // Scan the new page(s) 
   _twainSession.Acquire(TwainUserInterfaceFlags.Show); 
   // The pages should be added to the OCR document now. 
   // Recognize and save as PDF 
   _ocrDocument.Pages.Recognize(null); 
   _ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, null); 
   // Show the result PDF file 
   System.Diagnostics.Process.Start(pdfFileName); 
}

  14. Add the private method to handle the AcquirePageevent of the TwainSessionobject:

    C#
    VB
    Private Sub _twainSession_AcquirePage(ByVal sender As Object, ByVal e As TwainAcquirePageEventArgs) 
   ' We have a page 
   Dim image As RasterImage = e.Image 
   ' First, run the image processing commands on it 
   ' Deskew 
   deskewCmd.Run(image) 
   ' Despeckle 
   despeckleCmd.Run(image) 
   ' The rest of the commands only work on 1 BPP image 
   If (image.BitsPerPixel = 1) Then 
      ' Dot Remove 
      dotRemoveCmd.Run(image) 
      ' Hole Punch Remove 
      holePunchRemoveCmd.Run(image) 
      ' Vertical Line Remove 
      lineRemoveCmd.Type = LineRemoveCommandType.Vertical 
      lineRemoveCmd.Run(image) 
      ' Horizontal Line Remove 
      lineRemoveCmd.Type = LineRemoveCommandType.Horizontal 
      lineRemoveCmd.Run(image) 
   End If 
   ' Add the image as a new page to the OCR document 
   _ocrDocument.Pages.AddPage(image, Nothing) 
End Sub 
                 
     
    private void _twainSession_AcquirePage(object sender, TwainAcquirePageEventArgs e) 
{ 
   // We have a page 
   RasterImage image = e.Image; 
   // First, run the image processing commands on it 
   // Deskew 
   deskewCmd.Run(image); 
   // Despeckle 
   despeckleCmd.Run(image); 
   // The rest of the commands only work on 1 BPP image 
   if(image.BitsPerPixel == 1) 
   { 
      // Dot Remove 
      dotRemoveCmd.Run(image); 
      // Hole Punch Remove 
      holePunchRemoveCmd.Run(image); 
      // Vertical Line Remove 
      lineRemoveCmd.Type = LineRemoveCommandType.Vertical; 
      lineRemoveCmd.Run(image); 
      // Horizontal Line Remove 
      lineRemoveCmd.Type = LineRemoveCommandType.Horizontal; 
      lineRemoveCmd.Run(image); 
   } 
   // Add the image as a new page to the OCR document 
   _ocrDocument.Pages.AddPage(image, null); 
}

  15. Build, and Run the program to test it. You can click the buttons in the following order to create the PDF file "Startup", "Add Page", "Save and Recognize", "Shutdown".
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