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+## Copyright (C) 1999,2000  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, write to the Free Software
+## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{I}= mat2gray (@var{M},[min max])
+## converts a matrix to a intensity image
+## @end deftypefn
+
+## Author:	Kai Habel <kai.habel@gmx.de>
+## Date:	22/03/2000
+
+function I = mat2gray (M, scale)
+
+  if (nargin < 1|| nargin > 2)
+    usage ("mat2gray(...) number of arguments must be 1 or 2");
+  endif
+
+  if (!is_matrix (M))
+    usage ("mat2gray(M,...) M must be a matrix");
+  endif
+
+  if (nargin == 1)
+    Mmin = min (min (M));
+    Mmax = max (max (M));
+  else 
+    if (isvector (scale))
+      Mmin = min (scale (1), scale (2));
+      Mmax = max (scale (1), scale (2));
+    endif
+  endif
+
+  I = (M < Mmin) .* 0;
+  I = I + (M >= Mmin & M < Mmax) .* (1 / (Mmax - Mmin) * (M - Mmin));
+  I = I + (M >= Mmax);
+
+endfunction