GetRasterImage() Method

Summary

Gets the current image data of this page as a raster image.

Syntax

C++/CLI

Java

Python

public RasterImage GetRasterImage()

public RasterImage getRasterImage()

RasterImage^ GetRasterImage();

def GetRasterImage(self):

Return Value

A RasterImage object that represent the current image data of this page.

Remarks

This method is the equivalent of calling GetRasterImage(OcrPageType.Current). For more information on the various copies of raster images used by the OCR page, refer to OcrPageType.

Once you add a page to an OCR document, the image data used to create the page is copied and stored inside the OCR engine even if the original object used to create the page was a RasterImage object. To get a RasterImage that represents this page, use GetRasterImage.

The RasterImage object that this method returns contains a copy of the page image data. Any modifications you make to the RasterImage object will not affect the page. To update the page image data, you must call SetRasterImage. Since the RasterImage object is a copy, you must dispose it by calling its RasterImage.Dispose method once you are done using it.

Once you obtain a RasterImage object for this page, you can use it with other parts of LEADTOOLS, for example, you can set it in the ImageViewer or RasterPictureBox controls for viewing inside your Windows Forms-based application. You can also perform your own image processing on the page as follows:

// Flip the 2nd page added to the OCR document  
// Get the page (index is zero-based)  
IOcrPage page = ocrDocument.Pages[1];  
    
// Get a RasterImage object that represents this page  
Leadtools.RasterImage image = page.GetRasterImage();  
    
// Flip it vertically  
Leadtools.ImageProcessing.FlipCommand flip = new Leadtools.ImageProcessing.FlipCommand();  
flip.Horizontal = false;  
flip.Run(image);  
    
// Set it back into the page  
page.SetRasterImage(image);  
    
// Dispose the image  
image.Dispose();

You can also get a RasterImage object representation of a page with the IOcrPageCollection.ExportPage methods.

The RasterImage object returned from this method will contain one page only. To get a multipage RasterImage object containing the image data of all or a specific range of the pages added to the OCR document, you can either create a RasterImage from the first then loop through the pages of the document and add the returned RasterImage objects to the first object with the RasterImage.AddPage method. Or you can use the IOcrPageCollection.ExportPages methods.

Example

using Leadtools; 
using Leadtools.Codecs; 
using Leadtools.Ocr; 
using Leadtools.Forms.Common; 
using Leadtools.Document.Writer; 
using Leadtools.WinForms; 
using Leadtools.Drawing; 
using Leadtools.ImageProcessing; 
using Leadtools.ImageProcessing.Color; 
 
public void OcrPageExample() 
{ 
   string tifFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.tif"); 
   string pdfFileName = Path.Combine(LEAD_VARS.ImagesDir, "Ocr1.pdf"); 
 
   // 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 this image to the document 
         IOcrPage ocrPage = ocrDocument.Pages.AddPage(tifFileName, null); 
 
         // Auto-recognize the zones in the page 
         ocrPage.AutoZone(null); 
 
         // Show its information 
         Console.WriteLine("Size: {0} by {1} pixels", ocrPage.Width, ocrPage.Height); 
         Console.WriteLine("Resolution: {0} by {1} dots/inch", ocrPage.DpiX, ocrPage.DpiX); 
         Console.WriteLine("Bits/Pixel: {0}, Bytes/Line: {1}", ocrPage.BitsPerPixel, ocrPage.BytesPerLine); 
 
         byte[] palette = ocrPage.GetPalette(); 
         int paletteEntries; 
         if (palette != null) 
            paletteEntries = palette.Length / 3; 
         else 
            paletteEntries = 0; 
 
         Console.WriteLine("Number of entries in the palette: {0}", paletteEntries); 
         Console.WriteLine("Original format of this page: {0}", ocrPage.OriginalFormat); 
         Console.WriteLine("Has this page been recognized? : {0}", ocrPage.IsRecognized); 
         ShowZonesInfo(ocrPage); 
 
         // 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(); 
   } 
} 
 
private void ShowZonesInfo(IOcrPage ocrPage) 
{ 
   Console.WriteLine("Zones:"); 
   foreach (OcrZone ocrZone in ocrPage.Zones) 
   { 
      int index = ocrPage.Zones.IndexOf(ocrZone); 
      Console.WriteLine("Zone index: {0}", index); 
      Console.WriteLine("  Id                  {0}", ocrZone.Id); 
      Console.WriteLine("  Bounds              {0}", ocrZone.Bounds); 
      Console.WriteLine("  ZoneType            {0}", ocrZone.ZoneType); 
      Console.WriteLine("  CharacterFilters:   {0}", ocrZone.CharacterFilters); 
      Console.WriteLine("----------------------------------"); 
   } 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 
   public const string OcrLEADRuntimeDir = @"C:\LEADTOOLS23\Bin\Common\OcrLEADRuntime"; 
}