top_hat ( Region, StructElement : RegionTopHat : : )

Compute the top hat of regions.

top_hat computes the opening of Region with StructElement. The difference between the original region and the result of the opening is called the top hat. In contrast to opening, which splits regions under certain circumstances, top_hat computes the regions removed by such a splitting.

The position of StructElement is meaningless, since an opening operation is invariant with respect to the choice of the reference point.

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 processed.

StructElement (input_object)
region -> object
Structuring element (position independent).

RegionTopHat (output_object)
region(-array) -> object
Result of the top hat operator.


Result

top_hat 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__, circle, ellipse, rectangle1, rectangle2, draw_region, store_coord, struct_elements, store_filled_polygon


Possible Successors

reduce_domain, select_shape, area_center, connection


Alternatives

opening, difference


See also

bottom_hat, morph_hat, grey_tophat, opening



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