EuclideanSkeleton

binary skeleton operation

SYNOPSIS

#include "dip_binary.h"

dip_Error dip_EuclideanSkeleton ( in, out, endpixelCondition, edgeCondition )

DATA TYPES

binary

FUNCTION

This function calculates an accurate (euclidean)skeleton. It tests Hilditch conditions to preserve topology. The algorithms uses the following distance metrics:

5	4-connected neighbor
7	8-connected neighbor
11	neighbors reachable with a knight's move

4	6-connected neighbors
6	18-connected neighbors
7	26-connected neighbors
9	neighbors reachable with knight's move
10	(2,1,1) neighbors
12	(2,2,1) neighbors

The edge parameter specifies whether the border of the image should be treated as object (DIP_TRUE) or as background (DIP_FALSE). See section 9.6, "Morphology-based operations", in "Fundamentals of Image Processing" for a description of the skeleton operation.

ARGUMENTS

Data type	Name	Description
`dip_Image`	`in`	Binary input image
`dip_Image`	`out`	Output image
`dip_EndpixelCondition`	`endpixelCondition`	Endpixel condition
`dip_Boolean`	`edgeCondition`	Edge condition

The dip_EndpixelCondition enumeration consists of the following flags:

Name	Description
`DIP_ENDPIXEL_CONDITION_LOOSE_ENDS_AWAY`	Loose ends are eaten away
`DIP_ENDPIXEL_CONDITION_NATURAL`	"natural" endpixel condition of this algorithm
`DIP_ENDPIXEL_CONDITION_KEEP_WITH_ONE_NEIGHBOR`	Keep endpoint if it has a neighbor
`DIP_ENDPIXEL_CONDITION_KEEP_WITH_TWO_NEIGHBORS`	Keep endpoint if it has two neighbors
`DIP_ENDPIXEL_CONDITION_KEEP_WITH_THREE_NEIGHBORS`	Keep endpoint if it has three neighbors

KNOWN BUGS

EuclideanSkeleton is only implemented for 2 and 3 D images.

EuclideanSkeleton does not process pixels in a 2-pixel border around the edge. If this is an issue, consider adding 2 pixels on each side of your image.

LITERATURE

"Improved metrics in image processing applied to the Hilditch skeleton", B.J.H. Verwer, 9th ICPR, Rome, November 14-17, 1988.

AUTHOR

Ben Verwer, adapted to DIPlib by Geert van Kempen.