skeleucl.c File Reference

Euclidean binary skeleton. More...

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Detailed Description

Euclidean binary skeleton.

Usage: skeleucl in.pgm connex [inhibit] out.pgm

Description: Euclidean binary skeleton.

The parameter connex indicates the connectivity of the binary object. Possible choices are 4, 8 in 2d and 6, 26 in 3d.

If the parameter inhibit is given and is a binary image name, then the points of this image (constraint set) will be left unchanged.

This operator is usually used with a constraint set (parameter inhibit) that is a subset of the exact Euclidean medial axis (see operator medialaxis).

Here is an example using the whole medial axis as constraint set:

medialaxis test.pgm 3 _1
threshold _1 1 _2
skeleucl test.pgm 8 _2 result.pgm

Intersesting subsets are obtained by filtering the medial axis, either based on the ball radiuses, or based on the bisector angle (see operator bisector). Below is a script showing how to proceed:

#!/bin/sh
USAGE="Usage: $0 in seuilR (in [1..infnty[) seuilA (in [0.001..pi]) out"
if [ $# -ne 4 ]
then
	echo $USAGE
        exit
fi
medialaxis $1 3 /tmp/skel2_tmp_m
threshold /tmp/skel2_tmp_m 1 /tmp/skel2_tmp_m1
skeleucl $1 8 /tmp/skel2_tmp_m1 /tmp/skel2_tmp_s
threshold /tmp/skel2_tmp_m $2 /tmp/skel2_tmp_ms
distc $1 3 /tmp/skel2_tmp_d
bisector /tmp/skel2_tmp_d /tmp/skel2_tmp_ms /tmp/skel2_tmp_a
threshold /tmp/skel2_tmp_a $3 /tmp/skel2_tmp_i
skeleton /tmp/skel2_tmp_s /tmp/skel2_tmp_d 8 /tmp/skel2_tmp_i $4
rm -f /tmp/skel2_tmp_*

References:
[CCZ07] M. Couprie, D. Coeurjolly and R. Zrour: "Discrete bisector function and Euclidean skeleton in 2D and 3D", Image and Vision Computing, Vol. 25, No. 10, pp. 1543-1556, 2007.

Types supported: byte 2d, byte 3d

Category: topobin

Author:

Michel Couprie