opening_circle ( Region : RegionOpening : Radius : )

Open a region with a circular structuring element.

opening_circle is defined as an erosion followed by a Minkowsi addition with a circular structuring element (see example). opening serves to eliminate small regions (smaller than the circular structuring element) and to smooth the boundaries of a region.


Parameters

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

RegionOpening (output_object)
region(-array) -> object
Opened regions.

Radius (input_control)
real -> real / integer
Radius of the circular structuring element.
Default value: 3.5
Suggested values: 1.5, 2.5, 3.5, 4.5, 5.5, 7.5, 9.5, 12.5, 15.5, 19.5, 25.5, 33.5, 45.5, 60.5, 110.5
Range of values: 0.5 <= Radius <= 511.5 (lin)
Minimum increment: 1.0
Recommended increment: 1.0


Example
/* Large regions in an aerial picture (beech trees or meadows): */
read_image(:Image:'wald1':) >
threshold__(Image:Light:80,255:) >
/* close the small gap */
closing_circle(Light:H:2:) >
/* selecting the large regions */
opening_circle(H:Large:20:).

Complexity

Let F1 be the area of the input region. Then the runtime complexity for one region is:

    O(4 * sqrt(F1) * Radius) .


Result

opening_circle 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__, connection, union1, watersheds, class_ndim1__


Possible Successors

reduce_domain, select_shape, area_center, connection


Alternatives

opening, dilation1, minkowski_add1, circle


See also

transpose



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