thin

thinning by border deletion

Calling Sequence

out = thin(img)

Parameters

img: Binary image containing one or more binary shapes. (foreground == 1, background == 0),
out: Internal skeleton, thinned version of the shapes in the input image.

Description

Function thin performs thinning of binary objects. It uses the Zhang-Suen, a de facto standard and simple technique. The resulting image, the skeleton, is not always connected and is very sensible to noise. It is also slower than a good skeletonization algorithm (see skel). For thin shapes, it should work faster and provide better quality. You will need some pruning criterium to eliminate spurs.

Examples

im=gray_imread(SIPDIR+'images/r.gif');
imshow(im,2);
skl = thin(im);
clf;
imshow(im+skl,[]);
// Quality is definitely inferior to that of good skeletonization
// methods, as in the following test
im=gray_imread(SIPDIR+'images/escher.png');
skl = thin(im);      // Ordinary thinning
clf;
xset('wdim',400,500);
subplot(1,2,1);
imshow(im+skl,[]);
xset('wdim',800,400);
skl = skel(im);      // multiscale euclidean skeletonization
subplot(1,2,2);
imshow(im+(skl >= 10),[]);
xset('wdim',800,400);

Authors

Ricardo Fabbri <ricardofabbri (AT) users DOT sf DOT net>

Availability

The latest version of the Scilab Image Processing toolbox can be found at

http://siptoolbox.sourceforge.net