matthiasm@8: % NONMAXSUP - Non-maximal Suppression
matthiasm@8: %
matthiasm@8: % Usage:  cim = nonmaxsup(im, radius)
matthiasm@8: %
matthiasm@8: % Arguments:   
matthiasm@8: %            im     - image to be processed.
matthiasm@8: %            radius - radius of region considered in non-maximal
matthiasm@8: %                     suppression (optional). Typical values to use might
matthiasm@8: %                     be 1-3.  Default is 1.
matthiasm@8: %
matthiasm@8: % Returns:
matthiasm@8: %            cim    - image with pixels that are not maximal within a 
matthiasm@8: %                     square neighborhood zeroed out.
matthiasm@8: 
matthiasm@8: % Copyright (C) 2002 Mark A. Paskin
matthiasm@8: %
matthiasm@8: % This program is free software; you can redistribute it and/or modify
matthiasm@8: % it under the terms of the GNU General Public License as published by
matthiasm@8: % the Free Software Foundation; either version 2 of the License, or
matthiasm@8: % (at your option) any later version.
matthiasm@8: %
matthiasm@8: % This program is distributed in the hope that it will be useful, but
matthiasm@8: % WITHOUT ANY WARRANTY; without even the implied warranty of
matthiasm@8: % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
matthiasm@8: % General Public License for more details.
matthiasm@8: %
matthiasm@8: % You should have received a copy of the GNU General Public License
matthiasm@8: % along with this program; if not, write to the Free Software
matthiasm@8: % Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
matthiasm@8: % USA.
matthiasm@8: %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
matthiasm@8: 
matthiasm@8: function cim = nonmaxsup(m, radius)
matthiasm@8:   if (nargin == 1) radius = 1; end
matthiasm@8:   % Extract local maxima by performing a grey scale morphological
matthiasm@8:   % dilation and then finding points in the corner strength image that
matthiasm@8:   % match the dilated image and are also greater than the threshold.
matthiasm@8:   sze = 2 * radius + 1;                   % Size of mask.
matthiasm@8:   mx = ordfilt2(m, sze^2, ones(sze));   % Grey-scale dilate.
matthiasm@8:   cim = sparse(m .* (m == mx));
matthiasm@8: 
matthiasm@8: