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scripts/image/rgb2ntsc.m

changeset 10289: 4b124317dc38
parent:4fbfce35012a
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (47 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1994, 1995, 1996, 1997, 1998, 1999, 2005, 2006, 2007, 2008

     2##               John W. Eaton

     3##

     4## This file is part of Octave.

     5##

     6## Octave is free software; you can redistribute it and/or modify it

     7## under the terms of the GNU General Public License as published by

     8## the Free Software Foundation; either version 3 of the License, or (at

     9## your option) any later version.

    10##

    11## Octave is distributed in the hope that it will be useful, but

    12## WITHOUT ANY WARRANTY; without even the implied warranty of

    13## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU

    14## General Public License for more details.

    15##

    16## You should have received a copy of the GNU General Public License

    17## along with Octave; see the file COPYING.  If not, see

    18## <http://www.gnu.org/licenses/>.

    19

    20## -*- texinfo -*-

    21## @deftypefn {Function File} {} rgb2ntsc (@var{rgb})

    22## Transform a colormap or image from RGB to NTSC.

    23## @seealso{ntsc2rgb}

    24## @end deftypefn

    25

    26## Author: Tony Richardson <arichard@stark.cc.oh.us>

    27## Created: July 1994

    28## Adapted-By: jwe

    29

    30function yiq = rgb2ntsc (rgb)

    31

    32  if (nargin != 1)

    33    print_usage ();

    34  endif

    35

    36  ## If we have an image convert it into a color map.

    37  if (ismatrix (rgb) && ndims (rgb) == 3)

    38    is_image = true;

    39    Sz = size (rgb);

    40    rgb = [rgb(:,:,1)(:), rgb(:,:,2)(:), rgb(:,:,3)(:)];

    41    ## Convert to a double image.

    42    if (isinteger (rgb))

    43      C = class (rgb);

    44      low = double (intmin (C));

    45      high = double (intmax (C));

    46      rgb = (double (rgb) - low) / (high - low);

    47    endif

    48  else

    49    is_image = false;

    50  endif

    51

    52  if (! ismatrix (rgb) || columns (rgb) != 3)

    53    error ("rgb2ntsc: argument must be a matrix of size Nx3 or NxMx3");

    54  endif

    55  

    56  ## Convert data

    57  trans = [ 0.299,  0.596,  0.211;

    58            0.587, -0.274, -0.523;

    59            0.114, -0.322,  0.312 ];

    60

    61  yiq = rgb * trans;

    62

    63  ## If input was an image, convert it back into one.

    64  if (is_image)

    65    yiq = reshape (yiq, Sz);

    66  endif

    67

    68endfunction