AutoPreprocess Method (IOcrPage)

C#
Visual Basic
WinRT C#
Objective-C
Java
WinRT JavaScript
C++

void AutoPreprocess( 
   OcrAutoPreprocessPageCommand command,
   OcrProgressCallback callback
)

'Declaration
 
Sub AutoPreprocess( _
   ByVal command As OcrAutoPreprocessPageCommand, _
   ByVal callback As OcrProgressCallback _
)

'Usage
 
Dim instance As IOcrPage
Dim command As OcrAutoPreprocessPageCommand
Dim callback As OcrProgressCallback
 
instance.AutoPreprocess(command, callback)

void AutoPreprocess( 
   OcrAutoPreprocessPageCommand command,
   OcrProgressCallback callback
)

- (void)autoPreprocess:(LTOcrAutoPreprocessPageCommand)command
                target:(id)target
              selector:(SEL)selector;

public void autoPreprocess(OcrAutoPreprocessPageCommand command,
                           OcrProgressListener callback)

function Leadtools.Forms.Ocr.IOcrPage.AutoPreprocess( 
   command ,
   callback 
)

void AutoPreprocess( 
   OcrAutoPreprocessPageCommand command,
   OcrProgressCallback^ callback
)

Parameters

command: The preprocessing command to perform.
callback: Optional callback to show operation progress.

Use this method to deskew, rotate or invert the image according to command. By performing auto pre-processing on a page, you can improve the image quality of draft mode faxes.

Use the OcrProgressCallback to show the operation progress or to abort it. For more information and an example, refer to OcrProgressCallback.

Call this method prior to calling Recognize or RecognizeText.

This method will call GetDeskewAngle, GetRotateAngle and IsInverted to determine whether the page needs processing, if the page does, this method will internally deskews, rotates or inverts the image accordingly.

If the image is skewed, GetDeskewAngle will return the angle needed to deskew the image, if you call AutoPreprocess on the page, all subsequent calls to GetDeskewAngle will return 0 since the image is no longer skewed. Same with GetRotateAngle and IsInverted.

This method works on both the current and processing version of the image. For example, if you add a page that is skewed and call AutoPreprocess width OcrAutoPreprocessPageCommand.Deskew, then obtain either the current or processing images with GetRasterImage(OcrPageType), you will get two raster image objects that are both rotated (deskewed).

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

Copy Code

Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Forms.Ocr
Imports Leadtools.Forms
Imports Leadtools.Forms.DocumentWriters
Imports Leadtools.WinForms
Imports Leadtools.ImageProcessing.Core
Imports Leadtools.Drawing

Public Sub AutoPreprocessExample()
   Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Clean.tif")
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Clean.pdf")
   ' 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)

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

         ' Auto-preprocess it
         ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Deskew, Nothing)
         ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Invert, Nothing)
         ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Rotate, Nothing)

         ' Recognize it and save it as PDF
         ocrPage.Recognize(Nothing)
         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 18\Bin\Common\OcrAdvantageRuntime"
End Class

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

public void AutoPreprocessExample()
{
   string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Clean.tif");
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Clean.pdf");
   // 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);

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

         // Auto-preprocess it
         ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Deskew, null);
         ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Invert, null);
         ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Rotate, null);

         // Recognize it and save it as PDF
         ocrPage.Recognize(null);
         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 18\Bin\Common\OcrAdvantageRuntime";
}

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

[TestMethod]
public async Task AutoPreprocessExample()
{
   string tifFileName = @"Assets\Clean.tif";
   string pdfFileName = "Clean.pdf";
   // 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);

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

   // Add this image 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);
   }

   // Auto-preprocess it
   ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Deskew, null);
   ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Invert, null);
   ocrPage.AutoPreprocess(OcrAutoPreprocessPageCommand.Rotate, null);

   // Recognize it and save it as PDF
   ocrPage.Recognize(null);
   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

IOcrPage Interface
IOcrPage Members
Recognize Method
OcrAutoPreprocessPageCommand Enumeration
GetDeskewAngle Method
GetRotateAngle Method
IsInverted Method
IOcrPageCollection Interface
IOcrZoneCollection Interface
OcrZone Structure
Programming with the LEADTOOLS .NET OCR