--- /dev/null
+## Copyright (C) 2000 Kai Habel
+##
+## 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{bool}= isbw (@var{BW})
+## Returns true for a black-white (binary) image.
+## All values must be either 0 or 1
+## @end deftypefn
+
+## Author: Kai Habel <kai.habel@gmx.de>
+## Date: 20/03/2000
+
+function bool = isbw (BW)
+
+ bool = 0;
+ if !(nargin == 1)
+ usage ("isbw(BW)");
+ endif
+
+ if !(ismatrix(BW))
+ return;
+ endif
+
+ bool = all (all ((BW == 1) + (BW == 0)));
+
+endfunction