--- /dev/null
+## 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} {} ntsc2rgb (@var{yiq})
+## Transform a colormap or image from NTSC to RGB.
+## @seealso{rgb2ntsc}
+## @end deftypefn
+
+## Author: Tony Richardson <arichard@stark.cc.oh.us>
+## Created: July 1994
+## Adapted-By: jwe
+
+function rgb = ntsc2rgb (yiq)
+
+ if (nargin != 1)
+ print_usage ();
+ endif
+
+ ## If we have an image convert it into a color map.
+ if (ismatrix (yiq) && ndims (yiq) == 3)
+ is_image = true;
+ Sz = size (yiq);
+ yiq = [yiq(:,:,1)(:), yiq(:,:,2)(:), yiq(:,:,3)(:)];
+ ## Convert to a double image.
+ if (isinteger (yiq))
+ C = class (yiq);
+ low = double (intmin (C));
+ high = double (intmax (C));
+ yiq = (double (yiq) - low) / (high - low);
+ endif
+ else
+ is_image = false;
+ endif
+
+ if (! ismatrix (yiq) || columns (yiq) != 3)
+ error ("ntsc2rgb: argument must be a matrix of size Nx3 or NxMx3");
+ endif
+
+ ## Convert data
+ trans = [ 1.0, 1.0, 1.0;
+ 0.95617, -0.27269, -1.10374;
+ 0.62143, -0.64681, 1.70062 ];
+
+ rgb = yiq * trans;
+
+ ## If input was an image, convert it back into one.
+ if (is_image)
+ rgb = reshape (rgb, Sz);
+ endif
+
+endfunction