Adds a page from a DIB (Device-independent bitmap) stored in unmanaged memory.
public IOcrPage AddDib(
IntPtr dib,
OcrProgressCallback callback
)
Overloads Function AddDib( _
ByVal dib As IntPtr, _
ByVal callback As OcrProgressCallback _
) As IOcrPage
IOcrPage^ AddDib(
IntPtr dib,
OcrProgressCallback^ callback
)
dib
An unmanaged pointer to the DIB (device-independent bitmap).
callback
Optional callback to show operation progress.
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;
do
{
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, false))
{
// 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
Marshal.FreeHGlobal(dib);
// 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 OcrLEADRuntimeDir = @"C:\LEADTOOLS 20\Bin\Common\OcrLEADRuntime";
}
Imports Leadtools
Imports Leadtools.Codecs
Imports Leadtools.Ocr
Imports Leadtools.Document.Writer
Imports Leadtools.Forms
Imports Leadtools.ImageProcessing.Core
Public Sub AddPageFromDibExample()
Dim tifFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif")
Dim bmpFileName As String = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.bmp")
Dim pdfFileName As String = 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 codecs As New RasterCodecs()
codecs.Convert(tifFileName, bmpFileName, RasterImageFormat.Bmp, 0, 0, 1,
Nothing)
End Using
' From MSDN
Const bitmapFileHeaderStructSize As Integer = 14
Dim dib As IntPtr = IntPtr.Zero
Using fs As FileStream = File.OpenRead(bmpFileName)
' Allocate the DIB
Dim dibSize As Integer = CInt(fs.Length) - bitmapFileHeaderStructSize
dib = Marshal.AllocHGlobal(dibSize)
Dim dibOffset As Integer = 0
' Now read it
fs.Seek(bitmapFileHeaderStructSize, SeekOrigin.Begin)
Const bufferSize As Integer = 1024 * 4
Dim buffer As Byte() = New Byte(bufferSize - 1) {}
Dim bytes As Integer = 0
Do
bytes = fs.Read(buffer, 0, bufferSize)
If bytes > 0 Then
Dim dibPtr As New IntPtr(dib.ToInt64() + dibOffset)
Marshal.Copy(buffer, 0, dibPtr, bytes)
dibOffset += bytes
End If
Loop While bytes > 0
End Using
' Create an instance of the engine
Using ocrEngine As IOcrEngine = OcrEngineManager.CreateEngine(OcrEngineType.LEAD, False)
' Start the engine using default parameters
ocrEngine.Startup(Nothing, Nothing, Nothing, LEAD_VARS.OcrLEADRuntimeDir)
' Create an OCR document
Using ocrDocument As IOcrDocument = ocrEngine.DocumentManager.CreateDocument()
' Add the image
ocrDocument.Pages.AddDib(dib, Nothing)
' Free the DIB since we do not need it anymore
Marshal.FreeHGlobal(dib)
' 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 OcrLEADRuntimeDir As String = "C:\LEADTOOLS 20\Bin\Common\OcrLEADRuntime"
End Class
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