bwskel

Read a 2-D grayscale image into the workspace. Display the image. Objects of interest are dark threads against a light background.

I = imread('threads.png');
imshow(I)

Skeletonization requires a binary image in which foreground pixels are 1 (white) and the background is 0 (black). To make the original image suitable for skeletonization, take the complement of the image so that the objects are light and the background is dark. Then, binarize the result.

Icomplement = imcomplement(I);
BW = imbinarize(Icomplement);
imshow(BW)

Perform skeletonization of the binary image using bwskel.

out = bwskel(BW);

Display the skeleton over the original image by using the labeloverlay function. The skeleton appears as a 1-pixel wide blue line over the dark threads.

imshow(labeloverlay(I,out,'Transparency',0))

Prune small spurs that appear on the skeleton and view the result. One short branch is pruned from a thread near the center of the image.

out2 = bwskel(BW,'MinBranchLength',15);
imshow(labeloverlay(I,out2,'Transparency',0))

Read a binary image into the workspace.

BW1 = imread('circbw.tif');

Skeletonize objects in the image by using the bwskel function.

BW2 = bwskel(BW1);

View the original image and the skeletonized image side by side.

montage({BW1,BW2},'BackgroundColor','blue','BorderSize',5)

Load a volumetric data set into the workspace. The name of the data set is spiralVol. Display the volume using volshow.

load spiralVol.mat
volshow(spiralVol);

Convert the spiralVol data set to a binary format, which is required by the bwskel function.

spiralVolLogical = imbinarize(spiralVol);

Skeletonize the spiral shape in the data set. Display the skeletonized volume with volshow.

spiralVolSkel = bwskel(spiralVolLogical);
volshow(spiralVolSkel);