update packages

[CreaPhase.git] / octave_packages / m / image / ind2gray.m

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+## Copyright (C) 1994-2012 John W. Eaton
+##
+## This file is part of Octave.
+##
+## Octave 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 3 of the License, or (at
+## your option) any later version.
+##
+## Octave 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 Octave; see the file COPYING.  If not, see
+## <http://www.gnu.org/licenses/>.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} {} ind2gray (@var{x}, @var{map})
+## Convert an Octave indexed image to a gray scale intensity image.
+## If @var{map} is omitted, the current colormap is used to determine the
+## intensities.
+## @seealso{gray2ind, rgb2ntsc, image, colormap}
+## @end deftypefn
+
+## Author: Tony Richardson <arichard@stark.cc.oh.us>
+## Created: July 1994
+## Adapted-By: jwe
+
+function y = ind2gray (x, map)
+
+  if (nargin < 1 || nargin > 2)
+    print_usage ();
+  elseif (nargin == 1)
+    map = colormap ();
+  endif
+
+  [rows, cols] = size (x);
+
+  ## Convert colormap to intensity values (the first column of the
+  ## result of the call to rgb2ntsc) and then replace indices in
+  ## the input matrix with indexed values in the output matrix (indexed
+  ## values are the result of indexing the intensity values by the
+  ## elements of x(:)).
+
+  y = reshape (((rgb2ntsc (map))(:,1))(x(:)), rows, cols);
+
+endfunction