erosion2 ( Region, StructElement : RegionErosion : Row, Column, Iterations : )

Erode a region (using a reference point).

erosion2 erodes the input regions with a structuring element (StructElement) having the reference point (Row,Column). erosion2 has a similar effect as erosion1, the difference being that the reference point of the structuring element can be chosen arbitrarily. The parameter Iterations 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 (StructElement) can be generated with operators such as circle, rectangle1, rectangle2, ellipse, draw_region, store_polygon, store_coord, etc.


Parameters

Region (input_object)
region(-array) -> object
Regions to be eroded.

StructElement (input_object)
region -> object
Structuring element.

RegionErosion (output_object)
region(-array) -> object
Eroded regions.

Row (input_control)
point.y -> integer
Row coordinate of the reference point.
Default value: 0
Range of values: 0 <= Row <= 511 (lin)
Minimum increment: 1
Recommended increment: 1

Column (input_control)
point.x -> integer
Column coordinate of the reference point.
Default value: 0
Range of values: 0 <= Column <= 511 (lin)
Minimum increment: 1
Recommended increment: 1

Iterations (input_control)
integer -> integer
Number of iterations.
Default value: 1
Suggested values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 15, 17, 20, 30, 40, 50
Range of values: 1 <= Iterations
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. The the runtime complexity for one region is:

    O(sqrt(F1) * sqrt(F2) * Iterations) .


Result

erosion2 returns TRUE if all parameters are correct. The behavior in case of empty or no input region can be set via:

  a) no region:    set_system(::'no_object_result',<RegionResult>:)
  b) empty region: set_system(::'empty_region_result',<RegionResult>:)
Otherwise, an exception is raised.


Possible Predecessors

threshold__, regiongrowing__, watersheds, class_ndim1__, circle, ellipse, rectangle1, rectangle2, draw_region, store_coord, struct_elements, store_filled_polygon


Possible Successors

reduce_domain, select_shape, area_center, connection


Alternatives

minkowski_sub2, minkowski_sub1, erosion1, erosion_golay, erosion_seq


See also

transpose, circle, rectangle2, store_polygon



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