area_center🔗
Short description🔗
area_center — Area and center of regions.
Signature🔗
area_center( region Regions, out integer Area, out point.y Row, out point.x Column )
Description🔗
The operator area_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_system).
Execution information🔗
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🔗
Regions (input_object) region(-array) → object
Region(s) to be examined.
Area (output_control) integer(-array) → (integer)
Area of the region.
Row (output_control) point.y(-array) → (real)
Line index of the center.
Column (output_control) point.x(-array) → (real)
Column index of the center.
Example🔗
(C)
threshold(&Image,&Seg,120.0,255.0)\;
connection(Seg,&Connected)\;
T_area_center(Connected,&Area,&Row,&Column)\;
#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_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>).
The behavior in case of empty region (the region is the empty set) is set via
set_system('empty_region_result',<Result>).
If necessary an exception is raised.
Combinations with other operators🔗
Module🔗
Foundation