A zone is a rectangular area or the union of specifically located rectangular areas in the image, up to full size, containing a feature of interest to the user. The union of rectangles must have a so-called "pizza box" shape: the top of each rectangle in the union must touch the bottom of the upper rectangle (i.e., the bottom of the upper one and the top of the lower one is exactly the same). A rectangle can touch at most one rectangle above and one below.
The image data covered by each zone is handled and processed (typically recognized) separately, according to zone-specific parameters. The zones of a HIG_REC_IMAGE image form a list, the zone list, which is attached to the image. The number of zones in the zone list can be examined at any time with the IG_REC_zones_count_get() function.
The characterizing attributes of a zone are the following:
- Bounding rectangle
- Type (determines the role of the zone in the image layout; e.g., Flowed text, Table, Graphic, and some others)
- User data that can be freely used by the application
- Checking control bit mask that controls checking the recognition results
- Filling method (specifies the nature of the zone content, i.e., how the zone's area was supposed to be filled originally)
- Recognition module (the recognition module to be applied for the zone)
- A Character Set filter
- User-written checking callback assigned to the zone
- User dictionary section assigned to the zone (for UD-checking)
The zone's filling method (FillingMethod) can take one of the following enumIGRecFillingMethod values:
- IG_REC_FM_DEFAULT: The default zone filling method. The actual zone filling method for all zones of this type will be enquired just before recognition, according to the setting previously specified with a separate call to the IG_REC_default_filling_method_set() .
- IG_REC_FM_OMNIFONT: The omnifont zone filling method. It denotes a machine printed text with any typeface that is not highly stylized.
- IG_REC_FM_DRAFTDOT9: The 9-pin draft dot-matrix zone filling method. It denotes a 9-pin draft dot-matrix printout.
- IG_REC_FM_OCRA: The OCR-A zone filling method.
- IG_REC_FM_OCRB: The OCR-B zone filling method.
- IG_REC_FM_DOTDIGIT: The dot-digit zone filling method.
- IG_REC_FM_DASHDIGIT: The dash-digit zone filling method.
- IG_REC_FM_ASIAN: Asian languages filling method.
- IG_REC_FM_NO_OCR: No recognition will be attempted.
This section also provides information about the following: