Recognizing A Form From A Set Of Master Forms

Take the following steps to start a project and to add some code that creates a set of master forms and uses them to recognize a filled form:

Start Visual Studio.
Choose File->New->Project... from the menu.
In the New Project dialog box, choose either "Visual C# Projects" or "VB Projects" in the Projects Type List, and choose "Windows Application" in the Templates List.
Type the project name as "Recognizing A Form" 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.
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, browse to the "C:\LEADTOOLS 20\Bin\Dotnet4\Win32" folder and select the following DLLs:
- Leadtools.dll
- Leadtools.Codecs.dll
- Leadtools.Codecs.Fax.dll
- Leadtools.Codecs.Tif.dll
- Leadtools.Forms.Common.dll
- Leadtools.Document.Writer.dll
- Leadtools.Ocr.dll
- Leadtools.Ocr.LEADEngine.dll
- Leadtools.Forms.Recognition.dll
- Leadtools.Forms.Recognition.Ocr.dll

Add the following lines at the top of the Form1.cs/Form1.vb file:

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Forms.Common; 
using Leadtools.Ocr; 
using Leadtools.Forms.Recognition; 
using Leadtools.Forms.Recognition.Ocr; 
using System.IO;

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Forms.Common 
Imports Leadtools.Ocr  
Imports Leadtools.Forms.Recognition 
Imports Leadtools.Forms.Recognition.Ocr 
Imports System.IO

Add the following members to the Form1 class:

//Create the recognition engine 
FormRecognitionEngine recognitionEngine = new FormRecognitionEngine(); 
RasterCodecs codecs; 
//Create the OCR Engine to use in the recognition 
IOcrEngine formsOCREngine;

'Create the recognition engine 
Dim recognitionEngine As FormRecognitionEngine = New FormRecognitionEngine() 
Dim codecs As RasterCodecs 
'Create the OCR Engine to use in the recognition 
Dim formsOCREngine As IOcrEngine

Add the following code to the Load event of the form (Form1_Load()):

try 
 { 
    string MY_LICENSE_FILE = "d:\\temp\\TestLic.lic"; 
                     
    // Unlock support 
    string MY_DEVELOPER_KEY = "xyz123abc"; 
    RasterSupport.SetLicense(MY_LICENSE_FILE, MY_DEVELOPER_KEY); 
                     
    codecs = new RasterCodecs(); 
    //Create a LEADTOOLS OCR Module - LEAD Engine and start it 
    formsOCREngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD, false); 
    formsOCREngine.Startup(codecs, null, null, @"C:\LEADTOOLS 20\Bin\Common\OcrLEADRuntime"); 
    //Add an OCRObjectManager to the recognition engines 
    //ObjectManager collection 
    OcrObjectsManager ocrObjectsManager = new OcrObjectsManager(formsOCREngine); 
    ocrObjectsManager.Engine = formsOCREngine; 
    recognitionEngine.ObjectsManagers.Add(ocrObjectsManager); 
 } 
 catch (Exception ex) 
 { 
    MessageBox.Show(ex.Message); 
 }

Try 
   Dim MY_LICENSE_FILE As String = "d:\temp\TestLic.lic" 
                    
   ' Unlock support 
   Dim MY_DEVELOPER_KEY As String = "xyz123abc" 
   RasterSupport.SetLicense(MY_LICENSE_FILE, MY_DEVELOPER_KEY) 
 
   codecs = New RasterCodecs() 
   'Create a LEADTOOLS OCR Module - LEAD Engine OCR Engine and start it 
   formsOCREngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD, False) 
   formsOCREngine.Startup(codecs, Nothing, Nothing, "C:\LEADTOOLS 20\Bin\Common\OcrLEADRuntime") 
   'Add an OCRObjectManager to the recognition engines 
   'ObjectManager collection 
   Dim ocrObjectsManager As OcrObjectsManager = New OcrObjectsManager(formsOCREngine) 
   ocrObjectsManager.Engine = formsOCREngine 
   recognitionEngine.ObjectsManagers.Add(ocrObjectsManager) 
Catch ex As Exception 
   MessageBox.Show(ex.Message) 
End Try

LEADTOOLS ships several master form images which we will use for this tutorial. The path to the images is hard-coded to the default install location so if you chose another path, you will need to change it accordingly. Add a button to the form and set its Text property to "Create Master Form Attributes" then double-click it and add the following code to its handler:

try 
{ 
   //Get master form filenames 
   //You may need to update the below path to point to the "Leadtools Images\Forms\MasterForm Sets\OCR" directory. 
   string [] masterFileNames = Directory.GetFiles(@"C:\Users\Public\Documents\LEADTOOLS Images\Forms\MasterForm Sets\OCR", 
                                                      "*.tif", 
                                                      SearchOption.AllDirectories); 
   foreach (string masterFileName in masterFileNames) 
   { 
      string formName = Path.GetFileNameWithoutExtension(masterFileName); 
      //Load the master form image 
      RasterImage image = codecs.Load(masterFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, -1); 
      //Create a new master form 
      FormRecognitionAttributes masterFormAttributes = recognitionEngine.CreateMasterForm(formName, Guid.Empty, null); 
      for (int i = 0; i < image.PageCount; i++) 
      { 
         image.Page = i + 1; 
         //Add the master form page to the recognition engine 
         recognitionEngine.AddMasterFormPage(masterFormAttributes, image, null); 
      } 
      //Close the master form and save it's attributes 
      recognitionEngine.CloseMasterForm(masterFormAttributes); 
      File.WriteAllBytes(formName + ".bin", masterFormAttributes.GetData()); 
   } 
   MessageBox.Show("Master Form Processing Complete", "Complete"); 
} 
catch(Exception ex) 
{ 
   MessageBox.Show(ex.Message); 
}

                  
Try 
   'Get master form filenames 
   'You may need to update the below path to point to the "Leadtools Images\Forms\MasterForm Sets\OCR" directory. 
   Dim masterFileNames As String() = Directory.GetFiles("C:\Users\Public\Documents\LEADTOOLS Images\Forms\MasterForm Sets\OCR", 
                                                            "*.tif", 
                                                            SearchOption.AllDirectories) 
   For Each masterFileName As String In masterFileNames 
      Dim formName As String = Path.GetFileNameWithoutExtension(masterFileName) 
      'Load the master form image  
      Dim image As RasterImage = codecs.Load(masterFileName, 0, CodecsLoadByteOrder.BgrOrGray, 1, -1) 
      'Create a new master form 
      Dim masterFormAttributes As FormRecognitionAttributes = recognitionEngine.CreateMasterForm(formName, Guid.Empty, Nothing) 
      Dim i As Integer = 0 
      Do While i < image.PageCount 
         image.Page = i + 1 
         'Add the master form page to the recognition engine 
         recognitionEngine.AddMasterFormPage(masterFormAttributes, image, Nothing) 
         i += 1 
      Loop 
      'Close the master form and save it's attributes 
      recognitionEngine.CloseMasterForm(masterFormAttributes) 
      File.WriteAllBytes(formName & ".bin", masterFormAttributes.GetData()) 
   Next masterFileName 
   MessageBox.Show("Master Form Processing Complete", "Complete") 
Catch ex As Exception  
   MessageBox.Show(ex.Message) 
End Try

LEADTOOLS ships several filled form images for each master form which we will use for this tutorial. Add a button to the form and set its Text property to "Recognize Form", then double-click it and add the following code to its handler:

try 
{ 
   //For this tutorial, we will use the sample W9 filled form. 
   //You may need to update the below path to point to "\LEADTOOLS Images\Forms\Forms to be Recognized\OCR\W9_OCR_Filled.tif". 
   string formToRecognize = @"C:\Users\Public\Documents\LEADTOOLS Images\Forms\Forms to be Recognized\OCR\W9_OCR_Filled.tif"; 
   RasterImage image = codecs.Load(formToRecognize, 0, CodecsLoadByteOrder.BgrOrGray, 1, -1); 
   //Load the image to recognize 
   FormRecognitionAttributes filledFormAttributes = recognitionEngine.CreateForm(null); 
   for (int i = 0; i < image.PageCount; i++) 
   { 
      image.Page = i + 1; 
      //Add each page of the filled form to the recognition engine 
      recognitionEngine.AddFormPage(filledFormAttributes, image, null); 
   } 
   recognitionEngine.CloseForm(filledFormAttributes); 
   string resultMessage = "The form could not be recognized"; 
   //Compare the attributes of each master form to the attributes of the filled form 
   string[] masterFileNames = Directory.GetFiles(Application.StartupPath, "*.bin"); 
   foreach (string masterFileName in masterFileNames) 
   { 
      FormRecognitionAttributes masterFormAttributes = new FormRecognitionAttributes(); 
      masterFormAttributes.SetData(File.ReadAllBytes(masterFileName)); 
      FormRecognitionResult recognitionResult = recognitionEngine.CompareForm(masterFormAttributes, filledFormAttributes, null); 
      //In this example, we consider a confidence equal to or greater 
      //than 90 to be a match 
      if(recognitionResult.Confidence >= 90) 
      { 
         resultMessage = String.Format("This form has been recognized as a {0}", Path.GetFileNameWithoutExtension(masterFileName)); 
         break; 
      } 
   } 
   MessageBox.Show(resultMessage, "Recognition Results"); 
} 
catch (Exception ex) 
{ 
   MessageBox.Show(ex.Message); 
}

Try 
   'For this tutorial, we will use the sample W9 filled form. 
   'You may need to update the below path to point to "\LEADTOOLS Images\Forms\Forms to be Recognized\OCR\W9_OCR_Filled.tif". 
   Dim formToRecognize As String = "C:\Users\Public\Documents\LEADTOOLS Images\Forms\Forms to be Recognized\OCR\W9_OCR_Filled.tif" 
   Dim image As RasterImage = codecs.Load(formToRecognize, 0, CodecsLoadByteOrder.BgrOrGray, 1, -1) 
   'Load the image to recognize 
   Dim filledFormAttributes As FormRecognitionAttributes = recognitionEngine.CreateForm(Nothing) 
   Dim i As Integer = 0 
   Do While i < image.PageCount image.Page = i + 1 
      'Add each page of the filled form to the recognition engine 
      recognitionEngine.AddFormPage(filledFormAttributes, image, Nothing) 
      i += 1 
   Loop 
   recognitionEngine.CloseForm(filledFormAttributes) 
   Dim resultMessage As String = "The form could not be recognized" 
   'Compare the attributes of each master form to the attributes of the filled form 
   Dim masterFileNames As String() = Directory.GetFiles(Application.StartupPath, "*.bin") 
   For Each masterFileName As String In masterFileNames 
      Dim masterFormAttributes As FormRecognitionAttributes = New FormRecognitionAttributes() 
      masterFormAttributes.SetData(File.ReadAllBytes(masterFileName)) 
      Dim recognitionResult As FormRecognitionResult = recognitionEngine.CompareForm(masterFormAttributes, filledFormAttributes, Nothing) 
      'In this example, we consider a confidence equal to or greater than 90 to be a match 
      If recognitionResult.Confidence >= 90 Then 
         resultMessage = String.Format("This form has been recognized as a {0}", Path.GetFileNameWithoutExtension(masterFileName)) 
         Exit For  
      End If 
   Next masterFileName  
   MessageBox.Show(resultMessage, "Recognition Results") 
Catch ex As Exception 
      MessageBox.Show(ex.Message) 
End Try

Add the below clean-up code to the FormClosing event handler:

if (formsOCREngine != null && formsOCREngine.IsStarted) 
   formsOCREngine.Shutdown();

If Not formsOCREngine Is Nothing AndAlso formsOCREngine.IsStarted 
   Then formsOCREngine.Shutdown() 
End If

Run the project and test it. Click the "Create Master Form Attributes" button first which will enumerate all master form images in the directory and save each of their attributes to the application directory. Next, click the "Recognize Form" button which will load a sample form image, generate its attributes, compare them to each master forms attributes, and display the results. NOTE: If you encounter an "Invalid File Format" or "Feature Not Supported" exception, please refer to the topic Invalid File Format/Feature Not Supported.