Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / bwconncomp.m

diff --git a/octave_packages/image-1.0.15/bwconncomp.m b/octave_packages/image-1.0.15/bwconncomp.m
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+## Copyright (C) 2010 Soren Hauberg
+##
+## 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} {@var{cc} = } bwconncomp (@var{BW})
+## @deftypefnx {Function File} {@var{cc} = } bwconncomp (@var{BW}, @var{connectivity})
+## Trace the boundaries of objects in a binary image.
+##
+## @code{bwconncomp} traces the boundaries of objects in a binary image @var{BW}
+## and returns information about them in a structure with the following fields.
+##
+## @table @t
+## @item Connectivity
+## The connectivity used in the boundary tracing.
+## @item ImageSize
+## The size of the image @var{BW}.
+## @item NumObjects
+## The number of objects in the image @var{BW}.
+## @item PixelIdxList
+## A cell array containing where each element corresponds to an object in @var{BW}.
+## Each element is represented as a vector of linear indices of the boundary of
+## the given object.
+## @end table
+##
+## The connectivity used in the tracing is by default 4, but can be changed
+## by setting the @var{connectivity} input parameter to 8. Sadly, this is not
+## yet implemented.
+## @seealso{bwlabel, bwboundaries, ind2sub}
+## @end deftypefn
+
+function CC = bwconncomp (bw, N = 4)
+  ## Check input
+  if (nargin < 1)
+    error ("bwconncomp: not enough input arguments");
+  endif
+  if (!ismatrix (bw) || ndims (bw) != 2)
+    error ("bwconncomp: first input argument must be a NxM matrix");
+  endif
+  if (!isscalar (N) || !any (N == [4])) #, 8]))
+    error ("bwconncomp: second input argument must be 4");
+  endif
+  
+  ## Trace boundaries
+  B = bwboundaries (bw, N);
+
+  ## Convert from (x, y) index to linear indexing
+  P = cell (numel (B), 1);
+  for k = 1:numel (B)
+    P {k} = sub2ind (size (bw), B {k} (:, 2), B {k} (:, 1));
+  endfor
+  
+  ## Return result
+  CC = struct ("Connectivity", N, "ImageSize", size (bw), "NumObjects", numel (B));
+  CC.PixelIdxList = P;
+endfunction