openingopeningOpeningOpeningopening (Operator)

Name

openingopeningOpeningOpeningopening — Open a region.

Signature

opening(Region, StructElement : RegionOpening : : )

Description

An openingopeningOpeningOpeningopening operation is defined as an erosion followed by a Minkowski addition. By applying openingopeningOpeningOpeningopening to a region, larger structures remain mostly intact, while small structures like lines or points are eliminated. In contrast, a closingclosingClosingClosingclosing operation results in small gaps being retained or filled up (see closingclosingClosingClosingclosing).

openingopeningOpeningOpeningopening serves to eliminate small regions (smaller than StructElementStructElementStructElementstructElementstruct_element) and to smooth the boundaries of a region. The position of StructElementStructElementStructElementstructElementstruct_element is meaningless, since an opening operation is invariant with respect to the choice of the reference point.

Structuring elements (StructElementStructElementStructElementstructElementstruct_element) can be generated with operators such as gen_circlegen_circleGenCircleGenCirclegen_circle, gen_rectangle1gen_rectangle1GenRectangle1GenRectangle1gen_rectangle1, gen_rectangle2gen_rectangle2GenRectangle2GenRectangle2gen_rectangle2, gen_ellipsegen_ellipseGenEllipseGenEllipsegen_ellipse, draw_regiondraw_regionDrawRegionDrawRegiondraw_region, gen_region_polygongen_region_polygonGenRegionPolygonGenRegionPolygongen_region_polygon, gen_region_pointsgen_region_pointsGenRegionPointsGenRegionPointsgen_region_points, etc.

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

RegionRegionRegionregionregion (input_object) region(-array) → object

Regions to be opened.

StructElementStructElementStructElementstructElementstruct_element (input_object) region → object

Structuring element (position-invariant).

RegionOpeningRegionOpeningRegionOpeningregionOpeningregion_opening (output_object) region(-array) → object

Opened regions.

Example (HDevelop)

* Large regions in an aerial picture (beech trees or meadows):
read_image(Image,'forest_road')
threshold(Image,Light,160,255)
gen_circle(StructElement,100,100,10)
* selecting the large regions
opening(Light,StructElement,Large)
* Selecting of edges with certain orientation:
read_image(Image,'fabrik')
sobel_amp(Image,Sobel,'sum_abs',3)
threshold(Sobel,Edges,10,255)
gen_rectangle2(StructElement,100,100,3.07819,20,1)
opening(Edges,StructElement,Direction)

Example (C)

/* simulation of opening */
my_opening(Hobject In, Hobject StructElement, Hobject *Out)
{
  Hobject  H;
  erosion1(In,StructElement,&H,1);
  minkowski_add1(H,StructElement,Out,1);
}

/* Large regions in an aerial picture (beech trees or meadows): */
read_image(&Image,"forest_road");
threshold(Image,&Light,160.0,255.0);
gen_circle(&StructElement,100.0,100.0,10.0);
/* selecting the large regions */
opening(Light,StructElement,&Large);

/* Selecting of edges with certain orientation: */
read_image(&Image,"fabrik");
sobel_amp(Image,&Sobel,"sum_abs",3);
threshold(Sobel,Edges,30.0,255.0);
gen_rectangle2(&StructElement,100.0,100.0,3.07819,20.0,1.0);
opening(Edges,StructElement,&Direction);

Example (C++)

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

main()
{
  HImage     img("forest_road");
  HWindow    w;

  cout << "Example: Large regions in an aerial picture: " << endl;
  cout << "Beech Trees or Meadows" << endl;

  /* Struct elements */
  HRegion      circ1  = HRegion::GenCircle (10, 10, 10);
  HRegion      rect1  = HRegion::GenRectangle2 (100, 100, 3.07819, 20, 1);

  /* Segmentation, opening () -> select large regions */
  HRegionArray regs   = (img >= 160).Connection();
  HRegionArray open   = regs.Opening (circ1);

                        img.Display (w);    w.Click ();
  w.SetColor ("red");   regs.Display (w);   w.Click ();
  w.SetColor ("green"); open.Display (w);   w.Click ();

  cout << "Example: Selecting of edges with certain orientation" << endl;

  HByteImage hbi ("fabrik");

  HImage  sobel = hbi.SobelAmp ("sum_abs", 3);
  regs = (sobel >= 30).Connection ();

  HRegionArray direc = regs.Opening (rect1);

                        hbi.Display (w);    w.Click ();
  w.SetColor ("red");   regs.Display (w);   w.Click ();
  w.SetColor ("blue");  sobel.Display (w);  w.Click ();
  w.SetColor ("green"); direc.Display (w);  w.Click ();

  return(0);
}

Example (HDevelop)

* Large regions in an aerial picture (beech trees or meadows):
read_image(Image,'forest_road')
threshold(Image,Light,160,255)
gen_circle(StructElement,100,100,10)
* selecting the large regions
opening(Light,StructElement,Large)
* Selecting of edges with certain orientation:
read_image(Image,'fabrik')
sobel_amp(Image,Sobel,'sum_abs',3)
threshold(Sobel,Edges,10,255)
gen_rectangle2(StructElement,100,100,3.07819,20,1)
opening(Edges,StructElement,Direction)

Complexity

Let F1 be the area of the input region, and F2 be the area of the structuring element. Then the runtime complexity for one region is:

Result

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

Otherwise, an exception is raised.

Possible Predecessors

thresholdthresholdThresholdThresholdthreshold, regiongrowingregiongrowingRegiongrowingRegiongrowingregiongrowing, connectionconnectionConnectionConnectionconnection, union1union1Union1Union1union1, watershedswatershedsWatershedsWatershedswatersheds, class_ndim_normclass_ndim_normClassNdimNormClassNdimNormclass_ndim_norm, gen_circlegen_circleGenCircleGenCirclegen_circle, gen_ellipsegen_ellipseGenEllipseGenEllipsegen_ellipse, gen_rectangle1gen_rectangle1GenRectangle1GenRectangle1gen_rectangle1, gen_rectangle2gen_rectangle2GenRectangle2GenRectangle2gen_rectangle2, draw_regiondraw_regionDrawRegionDrawRegiondraw_region, gen_region_pointsgen_region_pointsGenRegionPointsGenRegionPointsgen_region_points, gen_region_polygon_filledgen_region_polygon_filledGenRegionPolygonFilledGenRegionPolygonFilledgen_region_polygon_filled

Possible Successors

reduce_domainreduce_domainReduceDomainReduceDomainreduce_domain, select_shapeselect_shapeSelectShapeSelectShapeselect_shape, area_centerarea_centerAreaCenterAreaCenterarea_center, connectionconnectionConnectionConnectionconnection

Alternatives

minkowski_add1minkowski_add1MinkowskiAdd1MinkowskiAdd1minkowski_add1, erosion1erosion1Erosion1Erosion1erosion1, opening_circleopening_circleOpeningCircleOpeningCircleopening_circle

Module

Foundation

Operators

openingopeningOpeningOpeningopening (Operator)

Name

Signature

Description

Execution Information

Parameters

Example (HDevelop)

Example (C)

Example (C++)

Example (HDevelop)

Complexity

Result

Possible Predecessors

Possible Successors

Alternatives

See also

Module