LoadZones(Stream) Method

Summary

Loads zones from a single-page zones .NET stream.

Syntax

C++/CLI

Python

public void LoadZones( 
   Stream stream 
)

void LoadZones(  
   Stream^ stream 
)

def LoadZones(self,stream):

Parameters

stream
The .NET stream containing the zones to load.

Remarks

To save and load the zones of OCR pages, you can use one of these methods:

IOcrPage.SaveZones(fileName) or IOcrPage.SaveZones(stream): These methods save the zones of a particular OCR page to a single-page disk file or stream. These methods will not use the page number, and hence, the file or stream will contain zones that are not tied to any particular page and can be loaded back into any OCR page regardless of its number. To load these zones back into any OCR page, use IOcrPage.LoadZones(fileName) or IOcrPage.LoadZones(stream).
IOcrPage.SaveZones(fileName, pageNumber) or IOcrPage.SaveZones(stream, pageNumber): These methods save the zones of a particular OCR page to a multipage disk file or stream. If the file or stream exist previously, these methods will replace the zones specified in 'pageNumber' with the zones of the IOcrPage. If the file or stream does not contain zones for the specified page number, the zones will be appended to the file or stream at the end and can be loaded later using IOcrPage.LoadZones(fileName, pageNumber) or IOcrPage.LoadZones(stream, pageNumber).
IOcrDocument.SaveZones(fileName) or IOcrDocument.SaveZones(stream): These methods save the zones of all the OCR pages in a document to a multipage disk file or stream. The saved data will contain the page number of the zones. To load these zones, you can either use IOcrDocument.LoadZones(fileName) or IOcrDocument.LoadZones(stream) to load the zones from a multipage file or stream back into a multipage OCR document. Or IOcrPage.LoadZones(fileName, pageNumber) and IOcrPage.LoadZones(stream, pageNumber) to load any single page from a multipage OCR document into a particular OCR page.

Note on loading zones from a multipage zone file: If the file does not contain zones data with the correct page number, the engine will not load any zones for this page. After the method returns, any OCR page that did not have zones data will contain zero zones. (the Zones property contains 0 items). You can then use IOcrPage.AutoZone if required to re-zone this page.

Use this method to load the zones previously saved into a .NET stream with the SaveZones(stream) method. This method will load the zones in the first page found in the stream. To load the zones of a particular page, use LoadZones(stream, pageNumber).

The zones of this page will first be cleared prior to loading the new items.

After this method finishes, you can access the loaded zones in the Zones property.

To load and save the zones to a disk file, use LoadZones(fileName) and SaveZones(fileName).

Saving zones to an external file or a stream could be useful when you are processing forms. For example, you can load one of the forms and automatically find the zones inside it using AutoZone, if the automatic zone detection was not 100 percent satisfactory, you can update the zones in the Zones collection manually and then save the result with SaveZones(stream). Once the zones are saved. You can now process all similar forms in the following manner:

Add the form page or pages to an OCR document using the Pages collection of IOcrDocument.
Load the zones previously saved for each page using LoadZones(stream).
Skip calling AutoZone and directly call Recognize. This will also speed up the recognition process considerably.

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 OcrAutoZoneExample() 
{ 
   // Create an image with some text in it 
   RasterImage image = new RasterImage(RasterMemoryFlags.Conventional, 320, 200, 24, RasterByteOrder.Bgr, RasterViewPerspective.TopLeft, null, IntPtr.Zero, 0); 
   Rectangle imageRect = new Rectangle(0, 0, image.ImageWidth, image.ImageHeight); 
 
   IntPtr hdc = RasterImagePainter.CreateLeadDC(image); 
   using (Graphics g = Graphics.FromHdc(hdc)) 
   { 
      g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; 
      g.FillRectangle(Brushes.White, imageRect); 
 
      using (Font f = new Font("Arial", 20, FontStyle.Regular)) 
         g.DrawString("Normal line", f, Brushes.Black, 0, 0); 
 
      using (Font f = new Font("Courier New", 20, FontStyle.Regular)) 
         g.DrawString("Monospaced line", f, Brushes.Black, 0, 80); 
   } 
 
   RasterImagePainter.DeleteLeadDC(hdc); 
 
   string zonesFileName = Path.Combine(LEAD_VARS.ImagesDir, "MyZones.xml"); 
 
   // 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 page 
      using (IOcrPage ocrPage = ocrEngine.CreatePage(image, OcrImageSharingMode.AutoDispose)) 
      { 
         // Show the zones, there should be no zones yet 
         ShowZones("Right after the page was created", ocrPage); 
 
         // Perform default AutoZoning on the page 
         ocrPage.AutoZone(null); 
 
         // Show the zones, there should be two zones, one for each line 
         ShowZones("AutoZone with default parameters", ocrPage); 
 
         // Update the first zone manually 
         OcrZone ocrZone = ocrPage.Zones[0]; 
         ocrZone.ZoneType = OcrZoneType.Text; 
         ocrPage.Zones[0] = ocrZone; 
 
         // Show the zones 
         ShowZones("After updating the type of the first zone", ocrPage); 
 
         // Save the zones to a file and then clear them 
         ocrPage.SaveZones(zonesFileName); 
         ocrPage.Zones.Clear(); 
 
         // Show the zones, there should be no zones since we just cleared them 
         ShowZones("After calling save and clear", ocrPage); 
 
         // Re-load the zones 
         ocrPage.LoadZones(zonesFileName); 
         ShowZones("After re-loading the zones", ocrPage); 
      } 
 
      // Shutdown the engine 
      // Note: calling Dispose will also automatically shutdown the engine if it has been started 
      ocrEngine.Shutdown(); 
   } 
} 
 
private void ShowZones(string message, IOcrPage ocrPage) 
{ 
   Console.WriteLine("Zones after {0}:", message); 
   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("----------------------------------"); 
   } 
 
   Console.WriteLine("Hit enter to continue"); 
   //Console.ReadLine(); 
} 
 
static class LEAD_VARS 
{ 
   public const string ImagesDir = @"C:\LEADTOOLS23\Resources\Images"; 
   public const string OcrLEADRuntimeDir = @"C:\LEADTOOLS23\Bin\Common\OcrLEADRuntime"; 
}