1 ## Copyright (C) 1994-2012 John W. Eaton
3 ## This file is part of Octave.
5 ## Octave is free software; you can redistribute it and/or modify it
6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
8 ## your option) any later version.
10 ## Octave is distributed in the hope that it will be useful, but
11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 ## General Public License for more details.
15 ## You should have received a copy of the GNU General Public License
16 ## along with Octave; see the file COPYING. If not, see
17 ## <http://www.gnu.org/licenses/>.
20 ## @deftypefn {Function File} {} ind2gray (@var{x}, @var{map})
21 ## Convert an Octave indexed image to a gray scale intensity image.
22 ## If @var{map} is omitted, the current colormap is used to determine the
24 ## @seealso{gray2ind, rgb2ntsc, image, colormap}
27 ## Author: Tony Richardson <arichard@stark.cc.oh.us>
31 function y = ind2gray (x, map)
33 if (nargin < 1 || nargin > 2)
39 [rows, cols] = size (x);
41 ## Convert colormap to intensity values (the first column of the
42 ## result of the call to rgb2ntsc) and then replace indices in
43 ## the input matrix with indexed values in the output matrix (indexed
44 ## values are the result of indexing the intensity values by the
47 y = reshape (((rgb2ntsc (map))(:,1))(x(:)), rows, cols);