erosion_rectangle1erosion_rectangle1ErosionRectangle1ErosionRectangle1 (Operator)


erosion_rectangle1erosion_rectangle1ErosionRectangle1ErosionRectangle1 — Erode a region with a rectangular structuring element.


erosion_rectangle1(Region : RegionErosion : Width, Height : )

Herror erosion_rectangle1(const Hobject Region, Hobject* RegionErosion, const Hlong Width, const Hlong Height)

Herror T_erosion_rectangle1(const Hobject Region, Hobject* RegionErosion, const Htuple Width, const Htuple Height)

void ErosionRectangle1(const HObject& Region, HObject* RegionErosion, const HTuple& Width, const HTuple& Height)

HRegion HRegion::ErosionRectangle1(Hlong Width, Hlong Height) const

static void HOperatorSet.ErosionRectangle1(HObject region, out HObject regionErosion, HTuple width, HTuple height)

HRegion HRegion.ErosionRectangle1(int width, int height)


erosion_rectangle1erosion_rectangle1ErosionRectangle1ErosionRectangle1ErosionRectangle1 applies an erosion with a rectangular structuring element to the input regions RegionRegionRegionRegionregion. The size of the structuring rectangle is WidthWidthWidthWidthwidth x HeightHeightHeightHeightheight. The operator results in reduced regions, and the areas smaller than the rectangular mask are eliminated.

erosion_rectangle1erosion_rectangle1ErosionRectangle1ErosionRectangle1ErosionRectangle1 is a very fast operation because the height of the rectangle enters only logarithmically into the runtime complexity, while the width does not enter at all. This leads to excellent runtime efficiency, even in the case of very large rectangles (edge length > 100).

Regions containing small connecting strips between large areas are separated only seemingly. They remain logically one region.


To reduce a region by the same amount in all directions, WidthWidthWidthWidthwidth and HeightHeightHeightHeightheight must be odd. If this is not the case, the region is eroded by a larger amount at the right or at the bottom, respectively, than at the left or at the top.

Execution Information


RegionRegionRegionRegionregion (input_object)  region(-array) objectHRegionHRegionHobject

Regions to be eroded.

RegionErosionRegionErosionRegionErosionRegionErosionregionErosion (output_object)  region(-array) objectHRegionHRegionHobject *

Eroded regions.

WidthWidthWidthWidthwidth (input_control)  extent.x HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Width of the structuring rectangle.

Default value: 11

Suggested values: 1, 2, 3, 4, 5, 11, 15, 21, 31, 51, 71, 101, 151, 201

Typical range of values: 1 ≤ Width Width Width Width width ≤ 511 (lin)

Minimum increment: 1

Recommended increment: 1

HeightHeightHeightHeightheight (input_control)  extent.y HTupleHTupleHtuple (integer) (int / long) (Hlong) (Hlong)

Height of the structuring rectangle.

Default value: 11

Suggested values: 1, 2, 3, 4, 5, 11, 15, 21, 31, 51, 71, 101, 151, 201

Typical range of values: 1 ≤ Height Height Height Height height ≤ 511 (lin)

Minimum increment: 1

Recommended increment: 1


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


erosion_rectangle1erosion_rectangle1ErosionRectangle1ErosionRectangle1ErosionRectangle1 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_normClassNdimNormClassNdimNormClassNdimNorm

Possible Successors

reduce_domainreduce_domainReduceDomainReduceDomainReduceDomain, select_shapeselect_shapeSelectShapeSelectShapeSelectShape, area_centerarea_centerAreaCenterAreaCenterAreaCenter, connectionconnectionConnectionConnectionConnection


erosion1erosion1Erosion1Erosion1Erosion1, minkowski_sub1minkowski_sub1MinkowskiSub1MinkowskiSub1MinkowskiSub1

See also