IOcrPageCollection Interface

Represents the pages of an OCR document object.

IOcrPageCollection holds the pages currently added into an OCR document (IOcrDocument). IOcrDocument through the IOcrDocument.Pages holds a collection of IOcrPage object. Each of these IOcrPage objects contains the raster image used to create it (the image used when the page is loaded or added) and a group of OCR zones for the page either added manually or through auto-zoning.

In memory-based IOcrDocument, the IOcrPageCollection holds the pages. The user can recognize any or all of the pages at any time and pages can be added or removed at will.

In file-based IOcrDocument, the IOcrPageCollection is a store-only view of the pages. when page is added, a snap shot of the current recognition data is saved into the document. This data cannot be modified anymore and the page is no longer needed. The user must recognize the pages before they are added to the document and pages can only be added but not removed. In this mode, you can only use IOcrPageCollection.Add and IOcrPageCollection.Count. No other method or property is supported.

Memory-Based Documents

The following list contains the major functionality of the IOcrPageCollection interface of a memory-based document:

• Add new pages to an OCR document from raster image files. These files can be in disk files, a .NET stream (memory or otherwise) or even in a remote URL. The following table lists all the page addition method groups:

• Export pages from the OCR document to raster image files. You can save the pages in disk files, .NET streams or as a single or multi-page RasterImage object with any of the file formats supported by LEADTOOLS. The following table list all the page exporting method groups:

• Perform auto image preprocessing on a single or multiple pages in the OCR document through AutoPreprocess. These methods provide a shortcut for iterating through the pages in the collection and calling IOcrPage.AutoPreprocess on each page.
• Perform auto-zoning on a single or multiple pages in the OCR document through AutoZone. These methods provide a shortcut for iterating through the pages in the collection and calling IOcrPage.AutoZone on each page.
• Recognize a single or multiple pages in the OCR document through Recognize. These methods provide a shortcut for iterating through the pages in the collection and calling IOcrPage.Recognize on each page.

File-Based Documents

Only the following members are supported in file-based documents:

• Add: Adds an IOcrPage to the document by taking a snapshot of its correct recognition data.

• Count: Gets the number of pages in the document.

The LEADTOOLS OCR engine supports pages of dots per inch (DPI) values of 150 and greater. If you try to add a page with a DPI of less than 150 then the engine might be able to recognize any data from this page.

This example will load multiple-pages into an OCR document and saves the OCR result into a multiple-page PDF file.

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Forms.Ocr; 
using Leadtools.Forms.DocumentWriters; 
using Leadtools.Forms; 
using Leadtools.ImageProcessing.Core; 
 
public void PageCollectionExamples() 
{ 
   // For this example, we need a multi-page TIF file. 
   // Create a muti-page TIF from Ocr1.tif, Ocr2.tif, Ocr3.tif and Ocr4.tif 
   string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr.tif"); 
   if (File.Exists(tifFileName)) 
      File.Delete(tifFileName); 
 
   using (RasterCodecs codecs = new RasterCodecs()) 
   { 
      for (int i = 0; i < 4; i++) 
      { 
         string pageFileName = Path.Combine(LEAD_VARS.ImagesDir, string.Format("Ocr{0}.tif", i + 1)); 
         using (RasterImage image = codecs.Load(pageFileName)) 
            codecs.Save(image, tifFileName, RasterImageFormat.CcittGroup4, 1, 1, 1, -1, CodecsSavePageMode.Append); 
      } 
   } 
 
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr.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()) 
      { 
         // Load all the pages of the multi-page tif file we created into the form 
         ocrDocument.Pages.AddPages(tifFileName, 1, -1, null); 
         Console.WriteLine("{0} pages added to the document", ocrDocument.Pages.Count); 
 
         // Auto-zone 
         ocrDocument.Pages.AutoZone(null); 
 
         // Recognize 
         ocrDocument.Pages.Recognize(null); 
 
         // Save 
         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"; 
} 

Imports Leadtools 
Imports Leadtools.Codecs 
Imports Leadtools.Forms.Ocr 
Imports Leadtools.Forms.DocumentWriters 
Imports Leadtools.Forms 
Imports Leadtools.ImageProcessing.Core 
 
<TestMethod> 
Public Sub PageCollectionExamples() 
   ' For this example, we need a multi-page TIF file. 
   ' Create a muti-page TIF from Ocr1.tif, Ocr2.tif, Ocr3.tif and Ocr4.tif 
   Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr.tif") 
   If File.Exists(tifFileName) Then 
      File.Delete(tifFileName) 
   End If 
 
   Using codecs As New RasterCodecs() 
      For i As Integer = 0 To 3 
         Dim pageFileName As String = Path.Combine(LEAD_VARS.ImagesDir, String.Format("Ocr{0}.tif", i + 1)) 
         Using image As RasterImage = codecs.Load(pageFileName) 
            codecs.Save(image, tifFileName, RasterImageFormat.CcittGroup4, 1, 1, 1, 
             -1, CodecsSavePageMode.Append) 
         End Using 
      Next 
   End Using 
 
   Dim pdfFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr.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() 
         ' Load all the pages of the multi-page tif file we created into the form 
         ocrDocument.Pages.AddPages(tifFileName, 1, -1, Nothing) 
         Console.WriteLine("{0} pages added to the document", ocrDocument.Pages.Count) 
 
         ' Auto-zone 
         ocrDocument.Pages.AutoZone(Nothing) 
 
         ' Recognize 
         ocrDocument.Pages.Recognize(Nothing) 
 
         ' Save 
         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 

Target Platforms

Reference

IOcrPageCollection Members

Leadtools.Forms.Ocr Namespace

OcrEngineManager Class

OcrEngineType Enumeration

IOcrPage Interface

Programming with the LEADTOOLS .NET OCR

Summary of All Supported Image File Formats

Working with OCR Pages