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AddDib Method

Adds a page from a DIB (Device-independent bitmap) stored in unmanaged memory.
public IOcrPage AddDib( 
   IntPtr dib, 
   OcrProgressCallback callback 
def AddDib(self,dib,callback): 


An unmanaged pointer to the DIB (device-independent bitmap).

Optional callback to show operation progress.

Return Value

The IOcrPage object that define the newly added page.


This method will add a device independent bitmap (DIB) stored in an unmanaged memory pointer to the OCR document.

This method will add the page to the end of the collection if you already have pages in this IOcrPageCollection.

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

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.

Note: The value of the "Recognition.ShareOriginalImage" (only supported by the LEADTOOLS OCR Module - LEAD Engine) setting is not used when calling this method. The engine loads the image(s) and sets them in the pages internally. The original image reference can be obtained from the page using IOcrPage.GetRasterImage(OcrPageType.Original). Sharing the original image minimizes the memory used during OCR operations.

This member only works with memory-based documents and will throw an exception otherwise. For more information, refer to IOcrDocumentManager.CreateDocument and Programming with the LEADTOOLS .NET OCR.


This example will add a raster image stored in an HTTP location to an OCR document

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Ocr; 
using Leadtools.Document.Writer; 
using Leadtools.Forms.Common; 
using Leadtools.ImageProcessing.Core; 
public void AddPageFromDibExample() 
   string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif"); 
   string bmpFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.bmp"); 
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf"); 
   // Get a DIB 
   // In this example, we will save the TIF file as BMP, then load it without the BITMAPFILEHEADER structure 
   // The result is a valid Windows DIB 
   using (RasterCodecs codecs = new RasterCodecs()) 
      codecs.Convert(tifFileName, bmpFileName, RasterImageFormat.Bmp, 0, 0, 1, null); 
   // From MSDN 
   const int bitmapFileHeaderStructSize = 14; 
   IntPtr dib = IntPtr.Zero; 
   using (FileStream fs = File.OpenRead(bmpFileName)) 
      // Allocate the DIB 
      int dibSize = (int)fs.Length - bitmapFileHeaderStructSize; 
      dib = Marshal.AllocHGlobal(dibSize); 
      int dibOffset = 0; 
      // Now read it 
      fs.Seek(bitmapFileHeaderStructSize, SeekOrigin.Begin); 
      const int bufferSize = 1024 * 4; 
      byte[] buffer = new byte[bufferSize]; 
      int bytes = 0; 
         bytes = fs.Read(buffer, 0, bufferSize); 
         if (bytes > 0) 
            IntPtr dibPtr = new IntPtr(dib.ToInt64() + dibOffset); 
            Marshal.Copy(buffer, 0, dibPtr, bytes); 
            dibOffset += bytes; 
      while (bytes > 0); 
   // Create an instance of the engine 
   using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD)) 
      // Start the engine using default parameters 
      ocrEngine.Startup(null, null, null, LEAD_VARS.OcrLEADRuntimeDir); 
      // Create an OCR document 
      using (IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument()) 
         // Add the image 
         ocrDocument.Pages.AddDib(dib, null); 
         // Free the DIB since we do not need it anymore 
         // Recognize 
         // Save 
         ocrDocument.Save(pdfFileName, DocumentFormat.Pdf, null); 
      // Shutdown the engine 
      // Note: calling Dispose will also automatically shutdown the engine if it has been started 
static class LEAD_VARS 
   public const string ImagesDir = @"C:\LEADTOOLS22\Resources\Images"; 
   public const string OcrLEADRuntimeDir = @"C:\LEADTOOLS22\Bin\Common\OcrLEADRuntime"; 

Target Platforms

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Leadtools.Ocr Assembly

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© 1991-2023 LEAD Technologies, Inc. All Rights Reserved.