IOcrEngine Interface

The IOcrEngine interface is your application entry point to the OCR functionality provided by LEADTOOLS.

LEADTOOLS OCR class library uses various interfaces to perform various OCR functions. These interfaces group logically related operations and encapsulates them from the rest of the toolkit. By using interfaces, LEADTOOLS ensures that you can use an engine-independent approach when programming your OCR-based application. At any time you can switch the engine type and ensure that your program will continue to function correctly. (Providing you have used the various "GetSupported" and "IsSupported" methods when dealing with engine-specific capabilities).

Obtain an instance of IOcrEngine by calling the OcrEngineManager.CreateEngine method with the appropriate engine type.

Once an instance is obtained, use the members of the IOcrEngine to perform various OCR tasks. OCR functions are grouped into "managers". Through these managers, you can create OCR documents (and add pages to these documents), perform zoning, recognition and saving the result documents. These managers are standard .NET interfaces with the implementation hidden inside the corresponding engine assembly. The following table lists the various "managers" and their main functionality:

The LEADTOOLS OCR engine is generally used in the following ways:

OCR an image file (or LEADTOOLS RasterImage object) and obtain the text with optional formatting and position info. In this mode, an IOcrDocument object is not needed since the result is not going to be saved. The IOcrEngine.CreatePage method can be used to quickly create an IOcrPage from the RasterImage directly, call the necessary method (such as IOcrPage.Recognize) and then obtain the text directly using IOcrPage.GetText or IOcrPage.GetRecognizedCharacters. For an example, refer to IOcrEngine.CreatePage.

Low-level OCRing of one or more pages and creating a final document such as PDF or DOCX. In this mode, the user generally creates an IOcrDocument object (in memory or file based) and then add IOcrPage objects to it. The pages can be previously recognized or are recognized at a later time. When all the pages are added and recognized, IOcrDocument.Save or IOcrDocument.SaveAsync is called to convert the recognition data to the final document. For an example, refer to IOcrDocument.

High-level OCRing from an input image file to a final document such as PDF or DOCX. In this mode, you can use IOcrAutoRecognizeManager to convert the document in one shot. Various events and logging mechanism can be used to modify and track the recognize operation. For an example, refer to IOcrAutoRecognizeManager.

The following example will convert an image file to a PDF document.

• C#
• Visual Basic
• WinRT C#
• WinRT JavaScript
• Silverlight C#
• Silverlight VB

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Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms.Ocr
Imports Leadtools.Forms.DocumentWriters

<TestMethod>
Public Sub OcrEngineExample()
   ' Create an instance of the engine
   Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, False)
      ' Start the engine using default parameters
      ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrAdvantageRuntimeDir)
      Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")
      Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf")

      ' Create an OCR document
      Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument()
         ' Add a page to the document
         Dim ocrPage As IOcrPage = ocrDocument.Pages.AddPage(tifFileName, Nothing)

         ' Recognize the page
         ' Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will
         ' check and automatically auto-zones the page
         ocrPage.AutoZone(Nothing)
         ocrPage.Recognize(Nothing)

         ' Save the document we have as PDF
         ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, Nothing)
      End Using

      ' Shutdown the engine
      ' Note: calling Dispose will also automatically shutdown the engine if it has been started
      ocrEngine.Shutdown()
   End Using
End Sub

Public NotInheritable Class LEAD_VARS
Public Const ImagesDir As String = "C:\Users\Public\Documents\LEADTOOLS Images"
Public Const OcrAdvantageRuntimeDir As String = "C:\LEADTOOLS 19\Bin\Common\OcrAdvantageRuntime"
End Class

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Forms.Ocr;
using Leadtools.Forms.DocumentWriters;

public void OcrEngineExample()
{
   // Create an instance of the engine
   using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false))
   {
      // Start the engine using default parameters
      ocrEngine.Startup(null, null, null, LEAD_VARS.OcrAdvantageRuntimeDir);
      string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif");
      string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf");

      // Create an OCR document
      using (IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument())
      {
         // Add a page to the document
         IOcrPage ocrPage = ocrDocument.Pages.AddPage(tifFileName, null);

         // Recognize the page
         // Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will
         // check and automatically auto-zones the page
         ocrPage.AutoZone(null);
         ocrPage.Recognize(null);

         // Save the document we have as PDF
         ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, null);
      }

      // Shutdown the engine
      // Note: calling Dispose will also automatically shutdown the engine if it has been started
      ocrEngine.Shutdown();
   }
}

static class LEAD_VARS
{
public const string ImagesDir = @"C:\Users\Public\Documents\LEADTOOLS Images";
public const string OcrAdvantageRuntimeDir = @"C:\LEADTOOLS 19\Bin\Common\OcrAdvantageRuntime";
}

using Leadtools;
using Leadtools.Codecs;
using Leadtools.Forms.Ocr;
using Leadtools.Forms.DocumentWriters;

      
public async Task OcrEngineExample()
{
   // Create an instance of the engine
   IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false);
   // Start the engine using default parameters
   ocrEngine.Startup(null, null, String.Empty, Tools.OcrEnginePath);

   string tifFileName = @"Assets\Ocr1.tif";
   string pdfFileName = "Ocr1.pdf";

   // Create an OCR document
   IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument();

   // Add a page to the document
   IOcrPage ocrPage = null;
   using (RasterCodecs codecs = new RasterCodecs())
   {
      StorageFile loadFile = await Tools.AppInstallFolder.GetFileAsync(tifFileName);
      using (RasterImage image = await codecs.LoadAsync(LeadStreamFactory.Create(loadFile)))
      {
         ocrPage = ocrDocument.Pages.AddPage(image, null);
      }
   }

   // Recognize the page
   // Note, Recognize can be called without calling AutoZone or manually adding zones. The engine will
   // check and automatically auto-zones the page
   ocrPage.AutoZone(null);
   ocrPage.Recognize(null);

   // Save the document we have as PDF
   StorageFile saveFile = await Tools.AppLocalFolder.CreateFileAsync(pdfFileName, CreationCollisionOption.ReplaceExisting);
   await ocrDocument.SaveAsync(LeadStreamFactory.Create(saveFile), DocumentFormat.Pdf, null);

   // Shutdown the engine
   ocrEngine.Shutdown();
}

Target Platforms

Reference

IOcrEngine Members
Leadtools.Forms.Ocr Namespace
OcrEngineManager Class
OcrEngineType Enumeration
Programming with the LEADTOOLS .NET OCR
Creating an OCR Engine Instance
Starting and Shutting Down the OCR Engine
Files to be Included with Your Application