Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / bwborder.m

diff --git a/octave_packages/image-1.0.15/bwborder.m b/octave_packages/image-1.0.15/bwborder.m
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+## Copyright (C) 2000  Etienne Grossmann
+##
+## This program is free software; you can redistribute it and/or modify
+## it under the terms of the GNU General Public License as published by
+## the Free Software Foundation; either version 2 of the License, or
+## (at your option) any later version.
+##
+## This program is distributed in the hope that it will be useful,
+## but WITHOUT ANY WARRANTY; without even the implied warranty of
+## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+## GNU General Public License for more details.
+##
+## You should have received a copy of the GNU General Public License
+## along with this program; If not, see <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {@var{b} = } bwborder (@var{im})
+## Finds the borders of foreground objects in a binary image.
+##
+## @var{b} is the borders in the 0-1 matrix @var{im}. 4-neighborhood is considered.
+## 
+## A pixel is on the border if it is set in @var{im}, and it has at least one
+## neighbor that is not set.
+## @end deftypefn
+
+## Author:        Etienne Grossmann <etienne@cs.uky.edu>
+## Last modified: January 2000
+
+function b = bwborder(im)
+
+[R,C]=size(im);
+
+b = im & ...
+    !([im(2:R,:) ;  zeros(1,C) ] & ...
+      [zeros(1,C); im(1:R-1,:) ] & ...
+      [im(:,2:C) ,  zeros(R,1) ] & ...
+      [zeros(R,1),  im(:,1:C-1)] ) ;