Operator Reference

HALCON Operator Reference / Filters / Misc
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gray_skeletongray_skeletonGraySkeletonGraySkeletongray_skeleton (Operator)

gray_skeletongray_skeletonGraySkeletonGraySkeletongray_skeleton — Thinning of gray value images.

Signature

gray_skeleton(Image : GraySkeleton : : )

Herror gray_skeleton(const Hobject Image, Hobject* GraySkeleton)

Herror T_gray_skeleton(const Hobject Image, Hobject* GraySkeleton)

void GraySkeleton(const HObject& Image, HObject* GraySkeleton)

HImage HImage::GraySkeleton() const

static void HOperatorSet.GraySkeleton(HObject image, out HObject graySkeleton)

HImage HImage.GraySkeleton()

def gray_skeleton(image: HObject) -> HObject

Description

gray_skeletongray_skeletonGraySkeletonGraySkeletongray_skeleton applies a gray value thinning operation to the input image ImageImageImageimageimage. Figuratively, the gray value “mountain range” is reduced to its ridge lines by setting the gray value of “hillsides” to the gray value at the corresponding valley bottom. The resulting ridge lines are at most two pixels wide. This operator is especially useful for thinning edge images, and is thus an alternative to nonmax_suppression_ampnonmax_suppression_ampNonmaxSuppressionAmpNonmaxSuppressionAmpnonmax_suppression_amp. In contrast to nonmax_suppression_ampnonmax_suppression_ampNonmaxSuppressionAmpNonmaxSuppressionAmpnonmax_suppression_amp, gray_skeletongray_skeletonGraySkeletonGraySkeletongray_skeleton preserves contours, but is much slower. In contrast to skeletonskeletonSkeletonSkeletonskeleton, this operator changes the gray values of an image while leaving its region unchanged.

Attention

Note that filter operators may return unexpected results if an image with a reduced domain is used as input. Please refer to the chapter Filters.

Execution Information

  • Multithreading type: reentrant (runs in parallel with non-exclusive operators).
  • Multithreading scope: global (may be called from any thread).
  • Automatically parallelized on tuple level.
  • Automatically parallelized on channel level.

Parameters

ImageImageImageimageimage (input_object)  (multichannel-)image(-array) → objectHImageHObjectHObjectHobject (byte / uint2)

Image to be thinned.

GraySkeletonGraySkeletonGraySkeletongraySkeletongray_skeleton (output_object)  (multichannel-)image(-array) → objectHImageHObjectHObjectHobject * (byte / uint2)

Thinned image.

Example (HDevelop)

* Seeking leafs of a beech tree in an aerial picture:
read_image(Image,'forest')
gray_skeleton(Image,Skelett)
mean_image(Skelett,MeanSkelett,7,7)
dyn_threshold(Skelett,MeanSkelett,Leafs,3,'light')

Example (C)

/* Seeking leafs of a tree in an aerial picture: */
read_image(&Image,"forest");
gray_skeleton(Image&,Skelett);
mean_image(Skelett,&MeanSkelett,7,7);
dyn_threshold(Skelett,MeanSkelett,&Leafs,3.0,"light");

Example (HDevelop)

* Seeking leafs of a beech tree in an aerial picture:
read_image(Image,'forest')
gray_skeleton(Image,Skelett)
mean_image(Skelett,MeanSkelett,7,7)
dyn_threshold(Skelett,MeanSkelett,Leafs,3,'light')

Example (HDevelop)

* Seeking leafs of a beech tree in an aerial picture:
read_image(Image,'forest')
gray_skeleton(Image,Skelett)
mean_image(Skelett,MeanSkelett,7,7)
dyn_threshold(Skelett,MeanSkelett,Leafs,3,'light')

Result

gray_skeletongray_skeletonGraySkeletonGraySkeletongray_skeleton returns 2 ( H_MSG_TRUE) if all parameters are correct. If the input is empty the behavior 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>). If necessary, an exception is raised.

Possible Successors

mean_imagemean_imageMeanImageMeanImagemean_image

Alternatives

nonmax_suppression_ampnonmax_suppression_ampNonmaxSuppressionAmpNonmaxSuppressionAmpnonmax_suppression_amp, nonmax_suppression_dirnonmax_suppression_dirNonmaxSuppressionDirNonmaxSuppressionDirnonmax_suppression_dir, local_maxlocal_maxLocalMaxLocalMaxlocal_max

See also

skeletonskeletonSkeletonSkeletonskeleton, gray_dilation_rectgray_dilation_rectGrayDilationRectGrayDilationRectgray_dilation_rect

Module

Foundation

ClassesClasses | | Operators