A binary contour follower

[x,y] = follow(Img)

[x,y] = follow(Img, 4)

[x,y] = follow(Img, 8)

- Img
- binary 2D array, 1 for object and 0 for background (class double)
- x y
- vectors, storing the parametrized contour.

Function `follow`

extracts parametric contours of binary
objects. This is useful for further extracting object features such as
curvature and bending energy.

It is assumed that Img has only one object

`x`

and `y`

both store the parametrized
contour. In other words, `(x(i), y(i))`

is a point of the
contour, where the coordinate system is assumed as starting from bottom-left
corner (0,0) to uper-right corner of the image. To get the (row,col) matrix
coordinates, use the transformation below:

row = size(Img,'r') - y col = x+1 |

The second argument is an optional parameter, being 4 or 8 depending if the border following is to be made in 4- or 8-neighborhood sequence, yielding a 4- or 8-connected contour.

follow(Img) equals follow(Img, 8).

- Ricardo Fabbri <ricardofabbri[at]users.sf.net>

http://siptoolbox.sf.net