Add a useful package (from Source forge) for octave

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

diff --git a/octave_packages/image-1.0.15/imerode.m b/octave_packages/image-1.0.15/imerode.m
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+## Copyright (C) 2004 Josep Mones i Teixidor  <jmones@puntbarra.com>
+## Copyright (C) 2008 Soren Hauberg
+## Copyright (C) 2011 Carnë Draug <carandraug+dev@gmail.com>
+## 
+## 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.
+
+## -*- texinfo -*-
+## @deftypefn {Function File} @var{B} = imerode (@var{A}, @var{se})
+## Perform morphological erosion on a given image.
+##
+## The image @var{A} must be a grayscale or binary image, and @var{se} must be a
+## structuring element. Both must have the same class, e.g., if @var{A} is a
+## logical matrix, @var{se} must also be logical.
+##
+## @seealso{imdilate, imopen, imclose}
+## @end deftypefn
+
+function retval = imerode(im, se)
+  ## Checkinput
+  if (nargin != 2)
+    print_usage();
+  endif
+  if (!ismatrix(im) || !isreal(im))
+    error("imerode: first input argument must be a real matrix");
+  elseif (!ismatrix(se) || !isreal(se))
+    error("imerode: second input argument must be a real matrix");
+  elseif ( !strcmp(class(im), class(se)) )
+    error("imerode: image and structuring element must have the same class");
+  endif
+
+  ## Perform filtering
+  ## If image is binary/logical, try to use filter2 (much faster)
+  if (islogical(im))
+    thr     = sum(se(:));
+    retval  = filter2(se,im) == thr;
+  else
+    retval  = ordfiltn(im, 1, se, 0);
+  endif
+
+endfunction