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########################################################################
##
## Copyright (C) 2000-2022 The Octave Project Developers
##
## See the file COPYRIGHT.md in the top-level directory of this
## distribution or <https://octave.org/copyright/>.
##
## 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
## <https://www.gnu.org/licenses/>.
##
########################################################################
## -*- texinfo -*-
## @deftypefn {} {@var{map} =} pink ()
## @deftypefnx {} {@var{map} =} pink (@var{n})
## Create color colormap. This colormap varies from black to white with
## shades of gray-pink.
##
## This colormap gives a sepia tone when used on grayscale images.
##
## The argument @var{n} must be a scalar.
## If unspecified, the length of the current colormap, or 64, is used.
## @seealso{colormap}
## @end deftypefn
function map = pink (n)
if (nargin == 1)
if (! isscalar (n))
error ("pink: N must be a scalar");
endif
n = double (n);
else
hf = get (0, "currentfigure");
if (! isempty (hf))
n = rows (get (hf, "colormap"));
else
n = 64;
endif
endif
if (n == 1)
map = sqrt ([1/3, 1/3, 1/3]);
elseif (n == 2)
map = sqrt ([1/3, 1/3, 1/6
1 1 1 ]);
elseif (n > 2)
x = [0:(n-1)]' / (n-1);
idx = floor (3/8 * n);
base = 1 / (3 * idx);
nel = idx; # number of elements
r(1:idx,1) = linspace (base, 2/3*x(idx) + 1/3, nel);
r(idx+1:n,1) = 2/3*x(idx+1:n) + 1/3;
g(1:idx,1) = 2/3*x(1:idx);
g(idx:2*idx,1) = linspace (2/3*x(idx), 2/3*x(2*idx) + 1/3, nel+1);
g(2*idx+1:n,1) = 2/3*x(2*idx+1:n) + 1/3;
nel = n - 2*idx + 1;
b(1:2*idx,1) = 2/3*x(1:2*idx);
b(2*idx:n,1) = linspace (2/3*x(2*idx), 1, nel);
map = sqrt ([r, g, b]);
else
map = zeros (0, 3);
endif
endfunction
%!demo
%! ## Show the 'pink' colormap profile and as an image
%! cmap = pink (256);
%! subplot (2, 1, 1);
%! rgbplot (cmap, "composite");
%! subplot (2, 1, 2);
%! rgbplot (cmap);
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