expand_grayexpand_grayExpandGrayExpandGrayexpand_gray (Operator)

Name

expand_grayexpand_grayExpandGrayExpandGrayexpand_gray — Fill gaps between regions (depending on gray value or color) or split overlapping regions.

Signature

expand_gray(Regions, Image, ForbiddenArea : RegionExpand : Iterations, Mode, Threshold : )

Description

expand_grayexpand_grayExpandGrayExpandGrayexpand_gray closes gaps between the input regions, which resulted from the suppression of small regions in a segmentation operator, (mode 'image'"image""image""image""image"), for example, or separates overlapping regions 'region'"region""region""region""region"). Both uses result from the expansion of regions. The operator works by adding a one pixel wide “strip” to a region, in which the gray values or color are different from the gray values or color of neighboring pixels on the region's border by at most ThresholdThresholdThresholdthresholdthreshold (in each channel). For images of type 'cyclic'"cyclic""cyclic""cyclic""cyclic" (e.g., direction images), also points with a gray value difference of at least 255 - ThresholdThresholdThresholdthresholdthreshold are added to the output region.

The expansion takes place only in regions, which are designated as not “forbidden” (parameter ForbiddenAreaForbiddenAreaForbiddenAreaforbiddenAreaforbidden_area). The number of iterations is determined by the parameter IterationsIterationsIterationsiterationsiterations. By passing 'maximal'"maximal""maximal""maximal""maximal", expand_grayexpand_grayExpandGrayExpandGrayexpand_gray iterates until convergence, i.e., until no more changes occur. By passing 0 for this parameter, all non-overlapping regions are returned. The two modes of operation ('image'"image""image""image""image" and 'region'"region""region""region""region") are different in the following ways:

'image'"image""image""image""image": The input regions are expanded iteratively until they touch another region or the image border, or the expansion stops because of too high gray value differences. Because expand_grayexpand_grayExpandGrayExpandGrayexpand_gray processes all regions simultaneously, gaps between regions are distributed evenly to all regions with a similar gray value. Overlapping regions are split by distributing the area of overlap evenly to both regions.
'region'"region""region""region""region": No expansion of the input regions is performed. Instead, only overlapping regions are split by distributing the area of overlap evenly to regions having a matching gray value or color.

Attention

Because regions are only expanded into areas having a matching gray value or color, usually gaps will remain between the output regions, i.e., the segmentation is not complete.

Execution Information

Multithreading type: reentrant (runs in parallel with non-exclusive operators).
Multithreading scope: global (may be called from any thread).
Processed without parallelization.

Parameters

RegionsRegionsRegionsregionsregions (input_object) region(-array) → object

Regions for which the gaps are to be closed, or which are to be separated.

ImageImageImageimageimage (input_object) (multichannel-)image → object (byte / cyclic)

Image (possibly multi-channel) for gray value or color comparison.

ForbiddenAreaForbiddenAreaForbiddenAreaforbiddenAreaforbidden_area (input_object) region → object

Regions in which no expansion takes place.

RegionExpandRegionExpandRegionExpandregionExpandregion_expand (output_object) region(-array) → object

Expanded or separated regions.

IterationsIterationsIterationsiterationsiterations (input_control) string → (string / integer)

Number of iterations.

Default: 'maximal' "maximal" "maximal" "maximal" "maximal"

Suggested values: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 'maximal'"maximal""maximal""maximal""maximal"

Value range: 1 ≤ Iterations Iterations Iterations iterations iterations ≤ 500 (lin)

Minimum increment: 1

Recommended increment: 1

ModeModeModemodemode (input_control) string → (string)

Expansion mode.

Default: 'image' "image" "image" "image" "image"

List of values: 'image'"image""image""image""image", 'region'"region""region""region""region"

ThresholdThresholdThresholdthresholdthreshold (input_control) integer(-array) → (integer)

Maximum difference between the gray value or color at the region's border and a candidate for expansion.

Default: 32

Suggested values: 5, 10, 15, 20, 25, 30, 40, 50

Value range: 1 ≤ Threshold Threshold Threshold threshold threshold ≤ 255 (lin)

Minimum increment: 1

Recommended increment: 5

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]);
  HRegion  empty_region;
  HWindow  win;

  image.Display (win);

  HRegionArray seg = (image >= 100).Connection ();

  seg.Display (win);
  HRegionArray exp = seg.ExpandGray1 (image, empty_region,
                                      "maximal", "image", 32);
  win.SetDraw ("margin");
  win.SetColored (12);
  exp.Display (win);
  win.Click ();

  return (0);
}

Example (C)

read_image(&Image,"fabrik");
disp_image(Image,WindowHandle);
regiongrowing(Image,&RawSegments,3,3,6.0,100);
set_colored(WindowHandle,12);
disp_region(RawSegments,WindowHandle);
expand_gray(RawSegments,Image,EMPTY_REGION,&Segments,"maximal","image",24);
disp_region(Segments,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]);
  HRegion  empty_region;
  HWindow  win;

  image.Display (win);

  HRegionArray seg = (image >= 100).Connection ();

  seg.Display (win);
  HRegionArray exp = seg.ExpandGray1 (image, empty_region,
                                      "maximal", "image", 32);
  win.SetDraw ("margin");
  win.SetColored (12);
  exp.Display (win);
  win.Click ();

  return (0);
}

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]);
  HRegion  empty_region;
  HWindow  win;

  image.Display (win);

  HRegionArray seg = (image >= 100).Connection ();

  seg.Display (win);
  HRegionArray exp = seg.ExpandGray1 (image, empty_region,
                                      "maximal", "image", 32);
  win.SetDraw ("margin");
  win.SetColored (12);
  exp.Display (win);
  win.Click ();

  return (0);
}

Result

expand_grayexpand_grayExpandGrayExpandGrayexpand_gray 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>), 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>), and the behavior in case of an empty result region via set_system('store_empty_region',<'true'/'false'>)set_system("store_empty_region",<"true"/"false">)SetSystem("store_empty_region",<"true"/"false">)SetSystem("store_empty_region",<"true"/"false">)set_system("store_empty_region",<"true"/"false">). If necessary, an exception is raised.

Possible Predecessors

connectionconnectionConnectionConnectionconnection, regiongrowingregiongrowingRegiongrowingRegiongrowingregiongrowing, pouringpouringPouringPouringpouring, class_ndim_normclass_ndim_normClassNdimNormClassNdimNormclass_ndim_norm

Possible Successors

select_shapeselect_shapeSelectShapeSelectShapeselect_shape

Module

Foundation

Operators

expand_grayexpand_grayExpandGrayExpandGrayexpand_gray (Operator)

Name

Signature

Description

Attention

Execution Information

Parameters

Example (C++)

Example (C)

Example (C++)

Example (C++)

Result

Possible Predecessors

Possible Successors

See also

Module