Operator Reference

HALCON Operator Reference / Regions / Features

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ClassesClasses | | Operators

area_centerarea_centerAreaCenterAreaCenterarea_center (Operator)

area_centerarea_centerAreaCenterAreaCenterarea_center — Area and center of regions.

Signature

area_center(Regions : : : Area, Row, Column)

Herror area_center(const Hobject Regions, Hlong* Area, double* Row, double* Column)

Herror T_area_center(const Hobject Regions, Htuple* Area, Htuple* Row, Htuple* Column)

void AreaCenter(const HObject& Regions, HTuple* Area, HTuple* Row, HTuple* Column)

HTuple HRegion::AreaCenter(HTuple* Row, HTuple* Column) const

Hlong HRegion::AreaCenter(double* Row, double* Column) const

static void HOperatorSet.AreaCenter(HObject regions, out HTuple area, out HTuple row, out HTuple column)

HTuple HRegion.AreaCenter(out HTuple row, out HTuple column)

int HRegion.AreaCenter(out double row, out double column)

def area_center(regions: HObject) -> Tuple[Sequence[int], Sequence[float], Sequence[float]]

def area_center_s(regions: HObject) -> Tuple[int, float, float]

Description

The operator area_centerarea_centerAreaCenterAreaCenterarea_center calculates the area and the center of the input regions. The area is defined as the number of pixels of a region. The center is calculated as the mean value of the line or column coordinates, respectively, of all pixels.

In the documentation of this chapter (Regions / Features), you can find an image illustrating regions which vary in their area.

If more than one region is passed the results are stored in tuples, the index of a value in the tuple corresponding to the index of the input region. In case of empty region all parameters have the value 0.0 if no other behavior was set (see set_systemset_systemSetSystemSetSystemset_system).

Execution Information

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Multithreading scope: global (may be called from any thread).
• Automatically parallelized on tuple level.

Parameters

RegionsRegionsRegionsregionsregions (input_object)  region(-array) → objectHRegionHObjectHObjectHobject

Region(s) to be examined.

AreaAreaAreaareaarea (output_control)  integer(-array) → HTupleSequence[int]HTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Area of the region.

RowRowRowrowrow (output_control)  point.y(-array) → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

Line index of the center.

ColumnColumnColumncolumncolumn (output_control)  point.x(-array) → HTupleSequence[float]HTupleHtuple (real) (double) (double) (double)

Column index of the center.

Example (C++)

#include "HIOStream.h"
#if !defined(USE_IOSTREAM_H)
using namespace std;
#endif
#include "HalconCpp.h"
using namespace Halcon;

main()
{
  Tuple   area, row, column;

  HImage   img ("monkey");
  HWindow  w;

  img.Display (w);
  w.Click ();

  HRegionArray   reg = (img >= 164).Connection ();

  reg.Display (w);
  w.Click ();

  area = reg.AreaCenter (&row, &column);

  for (int i = 0; i < reg.Num (); i++)
  {
    cout << "Row    [" << i << "]" << "= " << row[i].D ();
    cout << "\t\tColumn [" << i << "]" << "= " << column[i].D () << endl;
  }

  cout << "Total number of regions: " << reg.Num () << endl;
  return(0);
}

Example (C)

threshold(&Image,&Seg,120.0,255.0);
connection(Seg,&Connected);
T_area_center(Connected,&Area,&Row,&Column);

Example (C++)

#include "HIOStream.h"
#if !defined(USE_IOSTREAM_H)
using namespace std;
#endif
#include "HalconCpp.h"
using namespace Halcon;

main()
{
  Tuple   area, row, column;

  HImage   img ("monkey");
  HWindow  w;

  img.Display (w);
  w.Click ();

  HRegionArray   reg = (img >= 164).Connection ();

  reg.Display (w);
  w.Click ();

  area = reg.AreaCenter (&row, &column);

  for (int i = 0; i < reg.Num (); i++)
  {
    cout << "Row    [" << i << "]" << "= " << row[i].D ();
    cout << "\t\tColumn [" << i << "]" << "= " << column[i].D () << endl;
  }

  cout << "Total number of regions: " << reg.Num () << endl;
  return(0);
}

Example (C++)

#include "HIOStream.h"
#if !defined(USE_IOSTREAM_H)
using namespace std;
#endif
#include "HalconCpp.h"
using namespace Halcon;

main()
{
  Tuple   area, row, column;

  HImage   img ("monkey");
  HWindow  w;

  img.Display (w);
  w.Click ();

  HRegionArray   reg = (img >= 164).Connection ();

  reg.Display (w);
  w.Click ();

  area = reg.AreaCenter (&row, &column);

  for (int i = 0; i < reg.Num (); i++)
  {
    cout << "Row    [" << i << "]" << "= " << row[i].D ();
    cout << "\t\tColumn [" << i << "]" << "= " << column[i].D () << endl;
  }

  cout << "Total number of regions: " << reg.Num () << endl;
  return(0);
}

Complexity

If F is the area of a region the mean runtime complexity is O(sqrt(F)).

Result

The operator area_centerarea_centerAreaCenterAreaCenterarea_center returns the value 2 ( H_MSG_TRUE) if the input is not empty. The behavior in case of empty input (no input regions available) is set via the operator set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>). The behavior in case of empty region (the region is the empty set) is set via set_system('empty_region_result',<Result>)set_system("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)set_system("empty_region_result",<Result>). If necessary an exception is raised.

Possible Predecessors

thresholdthresholdThresholdThresholdthreshold, regiongrowingregiongrowingRegiongrowingRegiongrowingregiongrowing, connectionconnectionConnectionConnectionconnection

See also

select_shapeselect_shapeSelectShapeSelectShapeselect_shape

Module

Foundation

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ClassesClasses | | Operators