Operators

# dilation_circle (Operator)

## Name

dilation_circle — Dilate a region with a circular structuring element.

## Signature

dilation_circle(Region : RegionDilation : Radius : )

## Description

dilation_circle applies a Minkowski addition with a circular structuring element to the input regions Region. Because the circular mask is symmetrical, this is identical to a dilation. The size of the circle used as structuring element is determined by Radius.

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

## Attention

dilation_circle is applied to each input region separately. If gaps between different regions are to be closed, union1 or union2 has to be called first.

## Parallelization

• Multithreading type: reentrant (runs in parallel with non-exclusive operators).
• Automatically parallelized on tuple level.

## Parameters

Region (input_object)  region(-array) object

Regions to be dilated.

RegionDilation (output_object)  region(-array) object

Dilated regions.

Radius (input_control)  real (real / integer)

Radius of the circular structuring element.

Default value: 3.5

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

Typical range of values: 0.5 ≤ Radius ≤ 511.5 (lin)

Minimum increment: 1.0

Recommended increment: 1.0

## Example (C++ (HALCON 5.0-10.0))

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

main()
{
cout << "Reproduction of 'dilation_circle ()'" << endl;
cout << "First = original image " << endl;
cout << "Blue  = after dilation " << endl;
cout << "Red   = before dilation " << endl;

HByteImage img("monkey");
HWindow    w;

HRegion      circ   = HRegion::GenCircle (10, 10, 1.5);
HRegionArray regs   = (img >= 128).Connection();

img.Display (w);      w.Click ();
w.SetColor ("blue");  minadd.Display (w);   w.Click ();
w.SetColor ("red");   regs.Display (w);     w.Click ();

return(0);
}
```

## Complexity

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

## Result

dilation_circle 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.