connectionconnectionConnectionConnectionconnection (Operator)
connectionconnectionConnectionConnectionconnection — Compute connected components of a region.
Signature
def connection(region: HObject) -> HObject
Description
connectionconnectionConnectionConnectionconnection determines the connected components of the
input regions given in RegionRegionRegionregionregion. The neighborhood used for
this can be set via set_system('neighborhood',<4/8>)set_system("neighborhood",<4/8>)SetSystem("neighborhood",<4/8>)SetSystem("neighborhood",<4/8>)set_system("neighborhood",<4/8>).
The default is 8-neighborhood, which is useful for determining the
connected components of the foreground. The maximum number of
connected components that is returned by connectionconnectionConnectionConnectionconnection can be
set via set_system('max_connection',<Num>)set_system("max_connection",<Num>)SetSystem("max_connection",<Num>)SetSystem("max_connection",<Num>)set_system("max_connection",<Num>). The default
value of 0 causes all connected components to be returned.
The inverse operator of connectionconnectionConnectionConnectionconnection is union1union1Union1Union1union1.
Execution Information
- Multithreading type: reentrant (runs in parallel with non-exclusive operators).
- Multithreading scope: global (may be called from any thread).
- Automatically parallelized on internal data level.
Parameters
RegionRegionRegionregionregion (input_object) region(-array) → objectHRegionHObjectHObjectHobject
Input region.
ConnectedRegionsConnectedRegionsConnectedRegionsconnectedRegionsconnected_regions (output_object) region-array → objectHRegionHObjectHObjectHobject *
Connected components.
Example (HDevelop)
read_image(Image,'clip')
dev_set_colored(12)
threshold(Image,Dark,0,150)
count_obj(Dark,NumThresholded)
dev_display (Dark)
connection(Dark,ConnectedRegions)
count_obj(ConnectedRegions,NumConnected)
dev_display (ConnectedRegions)
Example (C)
read_image(&Image,"monkey");
set_colored(WindowHandle,12);
threshold(Image,&Light,150.0,255.0);
count_obj(Light,&Number1);
printf("Number of regions after threshold = %d\n",Number1);
disp_region(Light,WindowHandle);
connection(Light,&Many);
count_obj(Many,&Number2);
printf("Number of regions after threshold = %d\n",Number2);
disp_region(Many,WindowHandle);
Example (C++)
#include "HIOStream.h"
#if !defined(USE_IOSTREAM_H)
using namespace std;
#endif
#include "HalconCpp.h"
using namespace Halcon;
int main (int argc, char *argv[])
{
HImage image (argv[1]);
HWindow w;
w.SetColored(12);
HRegion Light = image >= 128;
Light.Display(w);
HRegionArray Many = Light.Connection();
cout << "Number of regions after threshold = " << Many.Num();
Many.Display(w);
}
Example (HDevelop)
read_image(Image,'clip')
dev_set_colored(12)
threshold(Image,Dark,0,150)
count_obj(Dark,NumThresholded)
dev_display (Dark)
connection(Dark,ConnectedRegions)
count_obj(ConnectedRegions,NumConnected)
dev_display (ConnectedRegions)
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(sqrt(F) * sqrt(N)).
Result
connectionconnectionConnectionConnectionconnection always returns the value 2 (
H_MSG_TRUE)
. The
behavior in case of empty input (no regions given) can be set via
set_system('no_object_result',<Result>)set_system("no_object_result",<Result>)SetSystem("no_object_result",<Result>)SetSystem("no_object_result",<Result>)set_system("no_object_result",<Result>)
and the behavior in case of an empty input region via
set_system('empty_region_result',<Result>)set_system("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)SetSystem("empty_region_result",<Result>)set_system("empty_region_result",<Result>).
If necessary, an exception is raised.
Possible Predecessors
auto_thresholdauto_thresholdAutoThresholdAutoThresholdauto_threshold,
thresholdthresholdThresholdThresholdthreshold,
dyn_thresholddyn_thresholdDynThresholdDynThresholddyn_threshold,
erosion1erosion1Erosion1Erosion1erosion1
Possible Successors
select_shapeselect_shapeSelectShapeSelectShapeselect_shape,
select_grayselect_graySelectGraySelectGrayselect_gray,
shape_transshape_transShapeTransShapeTransshape_trans,
set_coloredset_coloredSetColoredSetColoredset_colored,
dilation1dilation1Dilation1Dilation1dilation1,
count_objcount_objCountObjCountObjcount_obj,
reduce_domainreduce_domainReduceDomainReduceDomainreduce_domain,
add_channelsadd_channelsAddChannelsAddChannelsadd_channels
Alternatives
background_segbackground_segBackgroundSegBackgroundSegbackground_seg
See also
set_systemset_systemSetSystemSetSystemset_system,
union1union1Union1Union1union1
Module
Foundation