thn_lc

Name

thn_lc - Lee and Chen's thinning method.

Syntax

 #include <xite/thin.h>

 int thn_lc( int verbose, IBAND inband,
    IBAND outband );

Description

Thin a binary image with Lee and Chen's method. Black (0) is foreground, and white (255) is background.

This method is simply an extension of Zhang and Suen's method. First, Zhang and Suen's method is used. The skeleton thus obtained is not truly 8-connected, since some non-junction pixels have more than two neighbors, making the skeleton useless for algorithms that require this constraint. Therefore, some pixels have to be removed. The skeleton is inspected, and each pixel is tested using a lookup table. The result is a true 8-connected skeleton where only junction pixels have more than two 8-neighbors.

If verbose > 0, some messages are printed during execution.

Restrictions

inband must have pixel type unsigned byte. inband is assumed to be binary valued, with foreground = 0, background = 255.

Author

Řivind Due Trier, late one night at Michigan State University.

Reference

H.-J. Lee and B. Chen,

"Recognition of handwritten chinese characters via short line segments," Pattern Recognition, vol. 25, no. 5, pp. 543-552, 1992.