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−## Copyright (C) 2012 Roberto Metere <roberto@metere.it>
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−## Copyright (C) 2013 Carnë Draug <carandraug@octave.org>
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−##
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−## This program is free software; you can redistribute it and/or modify it under
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−## the terms of the GNU General Public License as published by the Free Software
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−## Foundation; either version 3 of the License, or (at your option) any later
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−## version.
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−##
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−## This program is distributed in the hope that it will be useful, but WITHOUT
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−## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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−## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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−## details.
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−##
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−## You should have received a copy of the GNU General Public License along with
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−## this program; if not, see <http://www.gnu.org/licenses/>.
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−
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−## -*- texinfo -*-
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−## @deftypefn {Function File} {@var{seq} =} getsequence (@var{se})
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−## Decompose structuring element.
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−##
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−## Returns a strel object @var{se} that can be indexed with @code{()} to obtain
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−## the decomposed structuring elements that can be used to "rebuild" @var{se}.
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−##
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−## @seealso{imdilate, imerode, strel}
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−## @end deftypefn
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−
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−function se = getsequence (se)
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−
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−  if (isempty (se.seq))
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−    ## guess a square/cube/rectangle/hyperrectangle shape even if shape
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−    ## is arbitrary. There's no need to decompose when it's very small
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−    ## hence the no bother if numel > 15
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−    if (se.flat && all (se.nhood(:)) && ! isvector (se.nhood) &&
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−        numel (se.nhood) > 15)
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−      nd = ndims (se.nhood);
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−      se.seq = cell (nd, 1);
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−      for idx = 1:nd
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−        vec_size      = ones (1, nd);
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−        vec_size(idx) = size (se.nhood, idx);
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−        se.seq{idx}   = strel ("arbitrary", true (vec_size));
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−      endfor
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−    elseif (strcmp (se.shape, "octagon") && se.opt.apothem > 0)
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−      persistent octagon_template = get_octagon_template ();
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−      se.seq = repmat (octagon_template, se.opt.apothem /3, 1);
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−    else
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−        se.seq{1,1} = se;
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−    endif
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−  endif
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−
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−endfunction
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−
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−function template = get_octagon_template ()
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−  template = repmat ({false(3)}, 4, 1);
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−  template{1}(2,:)     = true;
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−  template{2}(:,2)     = true;
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−  template{3}([1 5 9]) = true;
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−  template{4}([3 5 7]) = true;
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−  template = cellfun (@(x) strel ("arbitrary", x), template, "UniformOutput", false);
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−endfunction