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OcrZone Structure

Represents a rectangular area on a page containing a feature of interest to the user.
public struct OcrZone 
Public Structure OcrZone  
   Inherits System.ValueType 
@interface LTOcrZone : NSObject <NSCopying> 
public class OcrZone 
public value class OcrZone : public System.ValueType  

The OcrZone structure contains all the necessary information for describing a zone. A zone is a rectangular area on an image containing a feature of interest to the user. The image data covered by each zone is handled and processed (typically recognized) separately.

Access the zones of an IOcrPage object with the IOcrPage.Zones property. This is an IOcrZoneCollection allowing the user to examine and modify the various zones on the page.

Zones can be divided into two basic categories: whether a zone is to be recognized or whether it should be treated as graphic. Zones containing text information can be considered to be either of the flowing type or of a table type. This basic classification of zones helps the OCR engine handle text information correctly.

Use the CharacterFilters property to modify the set of valid characters for recognition of text zone. Specifying the character set correctly is a recognition accuracy issue.

Other members of the zone structure specify how the checking subsystem will function for the particular zone.

Construct the zones of a page automatically using IOcrPage.AutoZone. You must call this method and finish any modification you might have to the zones before calling IOcrPage.Recognize.

To modify a zone, use IOcrZoneCollection.Item to get the OcrZone object of interest, modify the zone then set it back through IOcrZoneCollection.Item. Note that since OcrZone is a structure (value type), use the setter. The following code snippet illustrates how to change the zone type of the 4th zone in an ocrPage:

// Remember, the index is zero-based, so 4th zone has an index of 3 
OcrZone zone = ocrPage.Zones[3]; 
// Prevent this zone from being recognized 
zone.ZoneType = OcrZoneType.Graphic; 
ocrPage.Zones[3] = zone; 

When adding or updating a zone directly initialize the OcrZone.Bounds, OcrZone.CharacterFilters and the OcrZone.ZoneType properties of the zone, since they will not take on their default values.

Do not modify the OcrZone.Id property. When adding zones, leave this value to the default of 0.

The OcrZone.ZoneType property of the updating zone should be one of the following: OcrZoneType.Text, OcrZoneType.Table or OcrZoneType.Graphics.

The preferred method of updating a zone is as illustrated in the code snippet above, first get the zone of interest, update it and set it back into the collection.

LEADTOOLS OCR .NET also supports OMR (Optical Mark Recognition) in all the engines. For more information, refer to Using OMR in LEADTOOLS .NET OCR.

If the zone is a table, the you can use IOcrTableZoneManager to get information and manipulate the cells properties.

To create an OcrZone object with all values initialized to default values, use OcrTypeManager.CreateDefaultOcrZone. This is a shortcut for languages that do not automatically initialize all the members of a structure, such as JavaScript.


For an example, refer to IOcrPage.AutoZone.


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