erosion2Erosion2Erosion2erosion2erosion2🔗

Short description🔗

erosion2Erosion2Erosion2erosion2erosion2 — Erode a region (using a reference point).

Signature🔗

erosion2( region Region, region StructElement, out region RegionErosion, point.y Row, point.x Column, integer Iterations )

Description🔗

erosion2Erosion2 erodes the input regions with a structuring element (StructElementstructElementstruct_element) having the reference point (Rowrowrow,Columncolumncolumn). erosion2Erosion2 has a similar effect as erosion1Erosion1, the difference is that the reference point of the structuring element can be chosen arbitrarily. The parameter Iterationsiterationsiterations 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 \(n\).

A maximum region is generated in case of an empty structuring element.

Structuring elements (StructElementstructElementstruct_element) can be generated with operators such as gen_circleGenCircle, gen_rectangle1GenRectangle1, gen_rectangle2GenRectangle2, gen_ellipseGenEllipse, draw_regionDrawRegion, gen_region_polygonGenRegionPolygon, gen_region_pointsGenRegionPoints, etc.

Execution information🔗

Execution information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).

Parameters🔗

Regionregionregion (input_object) region(-array) → objectHObjectHRegionHObjectHobject

Regions to be eroded.

StructElementstructElementstruct_element (input_object) region → objectHObjectHRegionHObjectHobject

Structuring element.

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

Eroded regions.

Rowrowrow (input_control) point.y → (integer)HTuple (Hlong)HTuple (int / long)intHtuple (Hlong)

Row coordinate of the reference point.

Default: 00
Value range: 0 ≤ Row ≤ 511 (lin)
Minimum increment: 1
Recommended increment: 1

Columncolumncolumn (input_control) point.x → (integer)HTuple (Hlong)HTuple (int / long)intHtuple (Hlong)

Column coordinate of the reference point.

Default: 00
Value range: 0 ≤ Column ≤ 511 (lin)
Minimum increment: 1
Recommended increment: 1

Iterationsiterationsiterations (input_control) integer → (integer)HTuple (Hlong)HTuple (int / long)intHtuple (Hlong)

Number of iterations.

Default: 11
Suggested values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 30, 40, 50
Value range: 1 ≤ 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:

\[\begin{eqnarray*} O(\sqrt{F1} \cdot \sqrt{F2} \cdot \textrm{Iterations}) \enspace . \end{eqnarray*}\]

Result🔗

erosion2Erosion2 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, gen_circleGenCircle, gen_ellipseGenEllipse, gen_rectangle1GenRectangle1, gen_rectangle2GenRectangle2, draw_regionDrawRegion, gen_region_pointsGenRegionPoints, gen_region_polygon_filledGenRegionPolygonFilled

Possible successors

reduce_domainReduceDomain, select_shapeSelectShape, area_centerAreaCenter, connectionConnection

Alternatives

minkowski_sub2MinkowskiSub2, minkowski_sub1MinkowskiSub1, erosion1Erosion1

Module🔗

Foundation