erosion_circleErosionCircleErosionCircleerosion_circleerosion_circle🔗

Short description🔗

erosion_circleErosionCircleErosionCircleerosion_circleerosion_circle — Erode a region with a circular structuring element.

Signature🔗

erosion_circle( region Region, out region RegionErosion, real Radius )

Description🔗

erosion_circleErosionCircle applies a Minkowski subtraction with a circular structuring element to the input regions Regionregionregion. Because the circular mask is symmetrical, this is identical to an erosion. The size of the circle used as structuring element is determined by Radiusradiusradius.

The operator results in reduced regions, smoothed region boundaries, and the regions smaller than the circular mask are eliminated. It is useful to select only values like \(3.5\), \(5.5\), etc. for Radiusradiusradius in order to avoid a translation of a region, because integer radii result in a circle having a non-integer center of gravity which is rounded to the next integer.

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🔗

Regionregionregion (input_object) region(-array) → objectHObjectHRegionHObjectHobject

Regions to be eroded.

RegionErosionregionErosionregion_erosion (output_object) region(-array) → objectHObjectHRegionHObjectHobject *

Eroded regions.

Radiusradiusradius (input_control) real → (real / integer)HTuple (double / Hlong)HTuple (double / int / long)Union[float, int]Htuple (double / Hlong)

Radius of the circular structuring element.

Default: 3.53.5
Suggested values: 1.5, 2.5, 3.5, 4.5, 5.5, 7.5, 9.5, 12.5, 15.5, 19.5, 25.5, 33.5, 45.5, 60.5, 110.5
Value range: 0.5 ≤ Radius ≤ 511.5 (lin)
Minimum increment: 1.0
Recommended increment: 1.0

Example🔗

(C)

my_erosion_circle(Hobject In, double Radius, Hobject *Out)
{
  Hobject Circle\;
  gen_circle(&Circle,100.0,100.0,Radius)\;
  minkowski_sub1(In,Circle,Out,1)\;
}

(C++)

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

main()
{
  cout << "Simulation of 'erosion_circle ()'" << endl\;
  cout << "First = original image " << endl\;
  cout << "Red   = after segmentation " << endl\;
  cout << "Blue  = after erosion " << endl\;
 HByteImage img("monkey")\;
  HWindow    w\;
 HRegion      circ   = HRegion::GenCircle (10, 10, 1.5)\;
  HRegionArray regs   = (img >= 128).Connection()\;
  HRegionArray minsub = regs.MinkowskiSub1 (circ, 1)\;
                        img.Display (w)\;      w.Click ()\;
  w.SetColor ("red")\;   regs.Display (w)\;     w.Click ()\;
  w.SetColor ("blue")\;  minsub.Display (w)\;   w.Click ()\;
 return(0)\;
}

Complexity🔗

Let \(F1\) be the area of an input region. Then the runtime complexity for one region is:

\[\begin{eqnarray*} O(2 \cdot \textrm{Radius} \cdot \sqrt{F1}) \enspace . \end{eqnarray*}\]

Result🔗

erosion_circleErosionCircle returns 2 (H_MSG_TRUE) if all parameters are correct. The behavior in case of empty or no input region can be set via:

no region: set_system('no_object_result',<RegionResult>)
empty region: set_system('empty_region_result',<RegionResult>)

Otherwise, an exception is raised.

Combinations with other operators🔗

Combinations

Possible predecessors

thresholdThreshold, regiongrowingRegiongrowing, watershedsWatersheds, class_ndim_normClassNdimNorm

Possible successors

connectionConnection, reduce_domainReduceDomain, select_shapeSelectShape, area_centerAreaCenter

Alternatives

minkowski_sub1MinkowskiSub1

Module🔗

Foundation