/usr/share/octave/packages/image-2.2.2/bwperim.m is in octave-image 2.2.2-1.
This file is owned by root:root, with mode 0o644.
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##
## This program 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.
##
## This program 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
## this program; if not, see <http://www.gnu.org/licenses/>.
## -*- texinfo -*-
## @deftypefn {Function File} {} bwperim (@var{bw})
## @deftypefnx {Function File} {} bwperim (@var{bw}, @var{conn})
## Find perimeter of objects in binary images.
##
## Values from the matrix @var{bw} are considered part of an object perimeter
## if their value is non-zero and is connected to at least one zero-valued
## element.
##
## Element connectivity @var{conn}, to define the size of objects, can be
## specified with a numeric scalar (number of elements in the neighborhood):
##
## @table @samp
## @item 4 or 8
## for 2 dimensional matrices;
## @item 6, 18 or 26
## for 3 dimensional matrices;
## @end table
##
## or with a binary matrix representing a connectivity array. Defaults to
## @code{conndef (ndims (@var{bw}), "minimal")} which is equivalent to
## @var{conn} of 4 and 6 for 2 and 3 dimensional matrices respectively.
##
## @seealso{bwarea, bwboundaries, imerode, mmgrad}
## @end deftypefn
function varargout = bwperim (bw, conn)
if (nargin < 1 || nargin > 2)
print_usage ();
elseif (! ismatrix (bw) || ! (isnumeric (bw) || islogical (bw)))
error("bwperim: BW must be a numeric matrix");
endif
nDims = ndims (bw);
if (nargin < 2)
## Defining default connectivity here because it's dependent
## on the first argument
conn = conndef (nDims, "minimal");
else
conn = make_conn ("bwperim", 2, nDims, conn);
endif
## Make sure bw is logical;
bw = logical (bw);
## Recover the elements that would get removed by erosion
perim = (! imerode (bw, conn)) & bw;
## Get the borders back (they are removed during erosion
tmp_idx = repmat ({":"}, [1 nDims]);
p_size = size (perim);
for dim = 1:nDims
idx = tmp_idx;
idx{dim} = [1 p_size(dim)];
perim(idx{:}) = bw(idx{:});
endfor
if (nargout > 0)
varargout{1} = perim;
else
imshow (perim);
endif
endfunction
%!shared in, out
%! in = [ 1 1 1 1 0 1 1 0 1 1
%! 1 1 0 1 1 1 1 1 1 0
%! 1 1 1 0 1 1 1 1 1 1
%! 1 1 1 1 0 1 1 1 0 1
%! 1 1 1 0 1 1 1 1 1 0
%! 1 1 1 1 1 1 0 1 0 1
%! 1 1 1 1 1 1 1 1 1 0
%! 1 1 1 1 1 1 1 1 1 1
%! 1 1 1 1 1 1 0 0 1 1
%! 1 1 1 1 0 1 0 1 1 0];
%!
%! out = [1 1 1 1 0 1 1 0 1 1
%! 1 1 0 1 1 0 0 1 1 0
%! 1 0 1 0 1 0 0 0 1 1
%! 1 0 0 1 0 1 0 1 0 1
%! 1 0 1 0 1 0 1 0 1 0
%! 1 0 0 1 0 1 0 1 0 1
%! 1 0 0 0 0 0 1 0 1 0
%! 1 0 0 0 0 0 1 1 0 1
%! 1 0 0 0 1 1 0 0 1 1
%! 1 1 1 1 0 1 0 1 1 0];
%!assert (bwperim (in), logical (out));
%!assert (bwperim (in, 4), logical (out));
%!
%! out = [1 1 1 1 0 1 1 0 1 1
%! 1 1 0 1 1 1 1 1 1 0
%! 1 1 1 0 1 1 0 1 1 1
%! 1 0 1 1 0 1 0 1 0 1
%! 1 0 1 0 1 1 1 1 1 0
%! 1 0 1 1 1 1 0 1 0 1
%! 1 0 0 0 0 1 1 1 1 0
%! 1 0 0 0 0 1 1 1 1 1
%! 1 0 0 1 1 1 0 0 1 1
%! 1 1 1 1 0 1 0 1 1 0];
%!assert (bwperim (in, 8), logical (out));
%!
%! out = [1 1 1 1 0 1 1 0 1 1
%! 1 0 0 0 0 1 0 0 1 0
%! 1 0 0 0 0 0 0 1 0 1
%! 1 0 1 0 0 0 0 0 0 1
%! 1 0 0 0 0 1 0 1 0 0
%! 1 0 0 0 1 0 0 0 0 1
%! 1 0 0 0 0 0 0 1 0 0
%! 1 0 0 0 0 1 1 0 0 1
%! 1 0 0 1 0 1 0 0 1 1
%! 1 1 1 1 0 1 0 1 1 0];
%!assert (bwperim (in, [1 0 0; 0 1 0; 0 0 1]), logical (out));
## test that any non-zero value is valid (even i and Inf)
%!shared in, out
%! in = [ 0 0 0 0 0 0 0
%! 0 0 5 0 0 1 9
%! 0 Inf 9 7 0 0 0
%! 0 1.5 5 7 1 0 0
%! 0 0.5 -1 89 i 0 0
%! 0 4 10 15 1 0 0
%! 0 0 0 0 0 0 0];
%! out = [0 0 0 0 0 0 0
%! 0 0 1 0 0 1 1
%! 0 1 0 1 0 0 0
%! 0 1 0 0 1 0 0
%! 0 1 0 0 1 0 0
%! 0 1 1 1 1 0 0
%! 0 0 0 0 0 0 0];
%!assert (bwperim (in), logical (out));
## test for 3D
%!shared in, out
%! in = reshape (magic(16), [8 8 4]) > 50;
%! out(:,:,1) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 1 1 1 0 1
%! 0 1 1 1 1 1 0 1
%! 1 1 0 1 1 1 1 1
%! 1 1 1 1 1 1 1 1
%! 1 1 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%! out(:,:,2) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 0 1 1 0 1
%! 0 1 0 0 0 1 0 1
%! 1 0 1 0 0 0 1 1
%! 1 0 0 1 0 1 0 1
%! 1 0 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%! out(:,:,3) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 0 1 1 0 1
%! 0 1 0 0 0 1 0 1
%! 1 0 0 0 0 0 1 1
%! 1 0 0 1 0 1 0 1
%! 1 0 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%! out(:,:,4) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 1 1 1 0 1
%! 0 1 1 1 1 1 0 1
%! 1 1 1 1 1 1 1 1
%! 1 1 1 1 1 1 1 0
%! 1 1 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%!assert (bwperim (in), logical (out));
%!
%! out(:,:,1) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 1 1 1 0 1
%! 0 1 1 1 1 1 0 1
%! 1 1 0 1 1 1 1 1
%! 1 1 1 1 1 1 1 1
%! 1 1 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%! out(:,:,2) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 1 1 1 0 1
%! 0 1 1 0 0 1 0 1
%! 1 1 1 1 0 1 1 1
%! 1 0 1 1 1 1 1 1
%! 1 0 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%! out(:,:,3) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 1 1 1 0 1
%! 0 1 0 0 0 1 0 1
%! 1 1 0 0 0 1 1 1
%! 1 0 1 1 1 1 1 1
%! 1 0 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%! out(:,:,4) = [
%! 1 1 0 1 0 1 1 1
%! 0 1 1 1 1 1 0 1
%! 0 1 1 1 1 1 0 1
%! 1 1 1 1 1 1 1 1
%! 1 1 1 1 1 1 1 0
%! 1 1 1 0 1 0 1 1
%! 1 1 1 0 1 0 1 1
%! 1 0 1 1 1 1 1 0];
%!assert (bwperim (in, 18), logical (out));
%!error bwperim ("text")
%!error bwperim (rand (10), 5)
%!error bwperim (rand (10), "text")
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