A zone is a rectangular area in the image, up to full size, containing a feature of interest to the user. The image data covered by each zone is handled and processed (and typically recognized) separately, according to zone-specific parameters. The zones of an ImGearRecPage Class image form a list, the zone list, which is attached to the image. The zone list can be examined at any time with the Zones Property of ImGearRecPage Class.

The characterizing attributes of a zone are the following:

• Size and position
• Identifier of the zone (identifies the zone in the zone list)
• Type (determines the role of the zone in the image layout, i.e., Flowed text, Table, or Graphic)
• Filling method (specifies the nature of the zone content, i.e., how the zone's area was supposed to be filled originally)
• Recognition method (the recognition module to be applied for the zone)
• A Character Set filter
• What kind of checking is enabled for the zone content
• User dictionary section assigned to the zone (for UD-checking)
• Checking event assigned to the zone for user-written checking

The zone's filling method (fm) can take one of the following ImGearRecFillingMethod Enumeration values:

• OMNIFONT : denotes machine printed text with any typeface that is not too stylized
• DRAFTDOT9 : denotes a 9-pin draft dot-matrix printout
• DRAFTDOT24 : denotes a 24-pin draft dot-matrix printout
• OCRA : denotes OCR-A zone filling
• OCRB : denotes OCR-B zone filling

There are two special filling methods worth mentioning separately:

• NO_OCR : denotes that no recognition should be attempted
• DEFAULT : allows a number of zones on the image to be handled together. For zones having this filling method, the recognition engine will apply a common value according to the setting previously given by the DefaultFillingMethod property of ImGearRecRecognitionSettings Class.

Add Zones 

Zones can be added to a given image (to the zone list of the image, to be precise) in three different ways:

• Manually
• From a File
• Automatically

Manually

In addition to, or instead of the automatic zone search, you can program your own zones by specifying the zone coordinates and zone attributes. For adding zones to the zone list manually, the application calls the Add Method of ImGearRecZoneCollection Class. Related methods are: Insert Method, Remove Method, RemoveAt Method, and Clear Method.

From a File

The third way of creating zones is by reading zones from a file (called a zone file) that contains the attributes of previously saved zones. An application can save the current zone definitions to a zone file any time with the ImGearRecZoneCollection.SaveToFile Method. The application can load them from a zone file with the LoadFromFile Method.

When a zone file is loaded, any previous zones on the image are removed.

If the application calls the ImGearRecPage.Recognize Method on an image with an empty zone list, the page-layout decomposition method is called automatically. 

Automatically

The automatic page-layout decomposition process (auto-zoning) can be activated directly by calling the ImGearRecZoneCollection.Locate Method for finding text blocks on the image. It creates an entire zone list for the given image.

The Locate Method has an overload that takes an ImGearRectangle as a parameter. This rectangle serves to limit the area of the image inside which zones will be searched and defined.

The recognition engine offers three different algorithms to be applied during auto-zoning: use the ImGearRecRecognitionSettings.DecompMethod Property to specify which Page parser algorithm setting should be applied during auto-zoning from among the following:

• STANDARD : The page parser algorithm introduced in the previous version of the toolkit
• LEGACY : The one incorporated in the earlier versions of the toolkit
• FAST : The quickest, but not able to handle complex cases (including tables)

In addition, the integrating application can set the zoning method to AUTO. With this setting, the recognition engine determines the method to use. See ImGearRecDecompositionMethod Enumeration for details.

Applying the new STANDARD algorithm results in the best throughput in overall accuracy, though in some cases it might require significantly more time to complete.

When auto-zoning is used, each resulting zone is initialized with the following:

• A unique auto-assigned zone identifier
• The zone's detected coordinates
• The zone type determined (FLOW, TABLE, or GRAPHIC)

All zones created by this method will have the following:

• The default filling method, DEFAULT
• The automatic recognition module selection AUTO setting
• The DEFAULT Character Set filter to specify the use of global filtering, if any
• None of the checking prohibit flags (e.g., LANGDICT_PROHIBIT) set

Any zone can be locally overridden with the Zones Property of ImGearRecPage, which allows you to access the zone list and change the attributes of a zone. 

using (ImGearRecPage recognitionPage = recognitionEngine.ImportPage((ImGearRasterPage)igPage))
  {
  //Decides which Page parser algorithm setting should be applied udring auto-zoning. 
  recognitionEngine.Recognition.DecompMethod = ImGearRecDecompositionMethod.AUTO;
  // Finds blocks of text on the image and creates a zone for each block.
  recognitionPage.Zones.Locate();
  // Determine the type of the text in the zones of a page (e.g. machine printed or dot-matrix printed text). 
  // The method performs a zone by zone analysis (instead of suggesting a general filling type for the entire image)
  // if the algorithm can determine a type for a given zone, the method replaces the DEFAULT value in the zone's 
  // ImGearRecZone.FillingMethod property by the determined one.
  recognitionPage.Zones.DetectFillingMethod();
  // Preprocess the page.
  recognitionPage.Image.Preprocess();
  // Perform recognition.
  recognitionPage.Recognize();                  
}

Using recognitionPage As ImGearRecPage = recognitionEngine.ImportPage(DirectCast(igPage, ImGearRasterPage))
' Decides which Page parser algorithm setting should be applied udring auto-zoning.
recognitionEngine.Recognition.DecompMethod = ImGearRecDecompositionMethod.AUTO
' Finds blocks of text on the image and creates a zone for each block.
recognitionPage.Zones.Locate()
' Determine the type of the text in the zones of a page (e.g. machine printed or dot-matrix printed text).
' The method performs a zone by zone analysis (instead of suggesting a general filling type for the entire image)
' if the algorithm can determine a type for a given zone, the method replaces the DEFAULT value in the zone's
' ImGearRecZone.FillingMethod property by the determined one.
recognitionPage.Zones.DetectFillingMethod()
' Preprocess the page.
recognitionPage.Image.Preprocess()
' Perform recognition.
recognitionPage.Recognize()
End Using

Detect Tables without Visible Cell Separators

Tables with visible grid lines (gridded tables) in an original page can usually be detected successfully by the auto-zoning method. However, tables without visible cell separators in the original are harder to identify as tables, because they could alternately be word lists or data arranged in columns. The recognition engine offers an algorithm for detecting such non-gridded tables more confidently. This feature can only be used in conjunction with an auto-zoning step. The algorithm to detect non-gridded tables is based on the result of character recognition. This algorithm will run only if all the following conditions are met:

• The zone list was created through auto-zoning
• There were no changes in the zone list (no zones were inserted or deleted)
• None of the zones in zone list were updated by modifying the zone coordinates
• The feature is enabled through the ImGearRecRecognitionSettings.DecompDetectNongriddedTablesEnabled Property

The code examples below show how to:

• Define a Zone Manually
• Update a Zone

Define a Zone Manually

The following example contains uppercase letters only for multi-lingual omnifont recognition:

ImGearRecZone igRecZone = new ImGearRecZone();
igRecZone.Rect.Left = 739;
igRecZone.Rect.Top = 63;
igRecZone.Rect.Right = 1729;
igRecZone.Rect.Bottom = 114;
// textual zone: this contains flowed text.
igRecZone.Type = ImGearRecZoneType.FLOW;
// Omnifont filling method was used to fill the zone's area.
igRecZone.FillingMethod = ImGearRecFillingMethod.OMNIFONT;
// MOR recognition module will be applied for the zone's area.
igRecZone.RecognitionModule = ImGearRecRecognitionModule.OMNIFONT_MOR;
// Character Set: this only has uppercase letters.
igRecZone.Filter = ImGearRecFilter.UPPERCASE;
// Add the zone to the zone list.
igRecPage.Zones.Add(igRecZone);
igRecPage.Zones.SaveToFile("SAMPLE.ZON");
MessageBox.Show("Number of Zones: " + igRecPage.Zones.Count);

Dim igRecZone As New ImGearRecZone()
igRecZone.Rect.Left = 739
igRecZone.Rect.Top = 63
igRecZone.Rect.Right = 1729
igRecZone.Rect.Bottom = 114
' textual zone: this contains flowed text.
igRecZone.Type = ImGearRecZoneType.FLOW
' Omnifont filling method was used to fill the zone's area.
igRecZone.FillingMethod = ImGearRecFillingMethod.OMNIFONT
' MOR recognition module will be applied for the zone's area.
igRecZone.RecognitionModule = ImGearRecRecognitionModule.OMNIFONT_MOR
' Character Set: this only has uppercase letters.
igRecZone.Filter = ImGearRecFilter.UPPERCASE
' Add the zone to the zone list.
igRecPage.Zones.Add(igRecZone)
igRecPage.Zones.SaveToFile("SAMPLE.ZON")
MessageBox.Show("Number of Zones: " + igRecPage.Zones.Count.ToString())

To get information about any particular zone of the zone list of the image, the application can access the zone list via the Zones Property of ImGearRecPage Class. This can be useful in finding out more about the zones created by the auto-zoning method.

Update a Zone

When updating a table-type zone by accessing the zone list via the Zones Property, the "cell-detection" algorithm won't be activated, which will result in improper table detection within the zone.

The program can detect cells within a table-zone if automatic page decomposition is used.

igRecPage.Zones.LoadFromFile("SAMPLE.ZON");
int nZones = igRecPage.Zones.Count;
// Get the first zone in the zone list.
ImGearRecZone igRecZone = igRecPage.Zones[0];
// . . .
// Adjust the left border of the zone by 50 pixels.
igRecZone.Rect.Left -= 50;
// Zone content will be handled as a flow text.
igRecZone.Type = ImGearRecZoneType.FLOW;
igRecPage.Zones.SaveToFile("SAMPLE.ZON");

igRecPage.Zones.LoadFromFile("SAMPLE.ZON")
Dim nZones As Integer = igRecPage.Zones.Count
' Get the first zone in the zone list.
Dim igRecZone As ImGearRecZone = igRecPage.Zones(0)
' . . .
' Adjust the left border of the zone by 50 pixels.
igRecZone.Rect.Left -= 50
' Zone content will be handled as a flow text.
igRecZone.Type = ImGearRecZoneType.FLOW
igRecPage.Zones.SaveToFile("SAMPLE.ZON")

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