connection ( Region : ConnectedRegions : : )

Compute connected components of a region.

connection determines the connected components of the input regions given in Region. The neighborhood used for this can be set via set_system(::'neighbourhood',<4/8>:) The default is 8-neighborhood, which is useful for determining the connected components of the foreground. The inverse operator of connection is union1.


Parameters

Region (input_object)
region(-array) -> object
Input region.

ConnectedRegions (output_object)
region-array -> object
Connected components.


Example
read_image(:Image:'affe':)
set_colored(::12:)
threshold__(Image:Light:150.0,255.0:)
count_obj(Light:::Number1)
fwrite_string(::'Nummber of regions after threshold = '+Number1:)
fnew_line(:::)
disp_region(Light:::)
connection(Light:Many::)
count_obj(Many:::Number2)
fwrite_string(::'Nummber of regions after threshold = '+Number2:)
fnew_line(:::)
disp_region(Many:::)

Complexity

Let F be the area of the input region and N be the number of generated connected components. Then the runtime complexity is O(F * N).


Result

connection always returns the value TRUE. The behavior in case of empty input (no regions given) can be set via set_system(::'no_object_result',<Result>:) and the behavior in case of an empty input region via set_system(::'empty_region_result',<Result>:). If necessary, an exception is raised.


Possible Predecessors

auto_threshold2, threshold__, dyn_threshold__, erosion1


Possible Successors

select_shape, select_grey__, shape_trans, set_colored, dilation1, count_obj, reduce_domain, add_channels


Alternatives

background_seg


See also

set_system, union1



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