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scripts/image/brighten.m

changeset 10289: 4b124317dc38
parent:eb63fbe60fab
author: John W. Eaton <jwe@octave.org>
date: Tue Feb 09 20:58:55 2010 -0500 (42 minutes ago)
permissions: -rw-r--r--
description: base_properties::set_children: account for hidden children 
     1## Copyright (C) 1999, 2000, 2007, 2009 Kai Habel

     2##

     3## This file is part of Octave.

     4##

     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.

     9##

    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.

    14##

    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/>.

    18

    19## -*- texinfo -*-

    20## @deftypefn {Function File} {@var{map_out} =} brighten (@var{map}, @var{beta})

    21## @deftypefnx {Function File} {@var{map_out} =} brighten (@var{h}, @var{beta})

    22## @deftypefnx {Function File} {@var{map_out} =} brighten (@var{beta})

    23## Darkens or brightens the given colormap.  If the @var{map} argument 

    24## is omitted, the function is applied to the current colormap.  The first

    25## argument can also be a valid graphics handle @var{h}, in which case 

    26## @code{brighten} is applied to the colormap associated with this handle.

    27##

    28## Should the resulting colormap @var{map_out} not be assigned, it will be

    29## written to the current colormap.

    30##

    31## The argument @var{beta} should be a scalar between -1 and 1,

    32## where a negative value darkens and a positive value brightens

    33## the colormap.

    34## @seealso{colormap}

    35## @end deftypefn

    36

    37function Rmap = brighten (m, beta)

    38  h = -1;

    39  if (nargin == 1)

    40    beta = m;

    41    m = colormap;

    42    h = gcf ();

    43  elseif (nargin == 2)

    44    if (ishandle (m))

    45      h = m;

    46      m = get (h, "colormap");

    47    elseif (! is_matrix (m) || size (m, 2) != 3)

    48      error ("brighten: first argument must be an Nx3 matrix or a handle");

    49    endif

    50  else

    51    print_usage ();

    52  endif

    53

    54  if (! isscalar (beta) || beta <= -1 || beta >= 1)

    55    error ("brighten: beta must be a scalar in the range (-1,1)");

    56  endif

    57

    58  if (beta > 0)

    59    gamma = 1 - beta;

    60  else

    61    gamma = 1 / (1 + beta);

    62  endif

    63

    64  if (nargout == 0)

    65    if (ishandle (h))

    66      set (h, "colormap", m .^ gamma);

    67    else

    68      colormap (m .^ gamma);

    69    endif

    70  else

    71    Rmap = m .^ gamma;

    72  endif

    73

    74endfunction