Add a useful package (from Source forge) for octave

[CreaPhase.git] / octave_packages / image-1.0.15 / ordfilt2.m

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+## Copyright (C) 2000 Teemu Ikonen
+##
+## 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 2
+## 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} {} ordfilt2(@var{A}, @var{nth}, @var{domain}, [@var{S}, @var{padding}])
+## Two dimensional ordered filtering.
+##
+## Ordered filter replaces an element of @var{A} with the @var{nth} 
+## element of the sorted set of neighbours defined by the logical 
+## (boolean) matrix @var{domain}.
+## Neighbour elements are selected to the sort if the corresponding 
+## element in the @var{domain} matrix is true.
+## 
+## The optional variable @var{S} is a matrix of size(@var{domain}). 
+## Values of @var{S} corresponding to nonzero values of domain are 
+## added to values obtained from @var{A} when doing the sorting.
+##
+## Optional variable @var{padding} determines how the matrix @var{A} 
+## is padded from the edges. See impad for details.
+## 
+## @seealso{medfilt2}
+## @end deftypefn
+
+
+## Author: Teemu Ikonen <tpikonen@pcu.helsinki.fi>
+## Created: 5.5.2000
+## Keywords: image processing filtering
+
+function retval = ordfilt2(A, nth, domain, varargin)
+
+S = zeros(size(domain));
+padding = "zeros";
+for i=1:length(varargin)
+  a = varargin{:};
+  if(ischar(a))
+    padding = a;
+  elseif(ismatrix(a) && size(a) == size(domain))
+    S = a;
+  endif
+endfor
+
+domain = logical(domain);
+
+xpad(1) = floor((size(domain, 2)+1)/2) - 1;
+xpad(2) = size(domain,2) - xpad(1) - 1;
+ypad(1) = floor((size(domain, 1)+1)/2) - 1;
+ypad(2) = size(domain,1) - ypad(1) - 1;
+
+if(ypad(1) >= size(A,1) || xpad(1) >= size(A,2))
+  error("domain matrix too large");
+endif;
+
+A = impad(A, xpad, ypad, padding);
+retval = __spatial_filtering__ (A, domain, "ordered", S, nth);
+
+endfunction