Operator Reference

HALCON Operator Reference / Morphology / Region
ClassesClasses | | Operators

erosion1erosion1Erosion1Erosion1erosion1 (Operator)

erosion1erosion1Erosion1Erosion1erosion1 — Erode a region.

Signature

Herror erosion1(const Hobject Region, const Hobject StructElement, Hobject* RegionErosion, const Hlong Iterations)

Herror T_erosion1(const Hobject Region, const Hobject StructElement, Hobject* RegionErosion, const Htuple Iterations)

void Erosion1(const HObject& Region, const HObject& StructElement, HObject* RegionErosion, const HTuple& Iterations)

HRegion HRegion::Erosion1(const HRegion& StructElement, Hlong Iterations) const

def erosion1(region: HObject, struct_element: HObject, iterations: int) -> HObject

Description

erosion1erosion1Erosion1Erosion1erosion1 erodes the input regions with a structuring element. By applying erosion1erosion1Erosion1Erosion1erosion1 to a region, its boundary gets smoothed. In the process, the area of the region is reduced. Furthermore, connected regions may be split. Such regions, however, remain logically one region. The erosion is a set-theoretic region operation. It uses the intersection operation.

Let M (StructElementStructElementStructElementstructElementstruct_element) and R (RegionRegionRegionregionregion) be two regions, where M is the structuring element and R is the region to be processed. Furthermore, let m be a point in M. Then the displacement vector is defined as the difference of the center of gravity of M and the vector . Let denote the translation of a region R by a vector . Then

For each point m in M a translation of the region R is performed. The intersection of all these translations is the erosion of R with M. erosion1erosion1Erosion1Erosion1erosion1 is similar to the operator minkowski_sub1minkowski_sub1MinkowskiSub1MinkowskiSub1minkowski_sub1, the difference is that in erosion1erosion1Erosion1Erosion1erosion1 the structuring element is mirrored at the origin. The position of StructElementStructElementStructElementstructElementstruct_element is meaningless, since the displacement vectors are determined with respect to the center of gravity of M.

The parameter IterationsIterationsIterationsiterationsiterations determines the number of iterations which are to be performed with the structuring element. The result of iteration n-1 is used as input for iteration n. From the above definition it follows that the maximum region is generated in case of an empty structuring element.

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) → objectHRegionHObjectHObjectHobject

Regions to be eroded.

StructElementStructElementStructElementstructElementstruct_element (input_object)  region → objectHRegionHObjectHObjectHobject

Structuring element.

RegionErosionRegionErosionRegionErosionregionErosionregion_erosion (output_object)  region(-array) → objectHRegionHObjectHObjectHobject *

Eroded regions.

IterationsIterationsIterationsiterationsiterations (input_control)  integer → HTupleintHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Number of iterations.

Default: 1

Suggested values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 30, 40, 50

Value range: 1 ≤ Iterations Iterations Iterations iterations iterations (lin)

Minimum increment: 1

Recommended increment: 1

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

erosion1erosion1Erosion1Erosion1erosion1 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, 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

connectionconnectionConnectionConnectionconnection, reduce_domainreduce_domainReduceDomainReduceDomainreduce_domain, select_shapeselect_shapeSelectShapeSelectShapeselect_shape, area_centerarea_centerAreaCenterAreaCenterarea_center

Alternatives

minkowski_sub1minkowski_sub1MinkowskiSub1MinkowskiSub1minkowski_sub1, minkowski_sub2minkowski_sub2MinkowskiSub2MinkowskiSub2minkowski_sub2, erosion2erosion2Erosion2Erosion2erosion2

See also

transpose_regiontranspose_regionTransposeRegionTransposeRegiontranspose_region

Module

Foundation

ClassesClasses | | Operators