--- /dev/null
+## Copyright (C) 2004 Josep Mones i Teixidor
+##
+## 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} {@var{B} = } nlfilter (@var{A}, [@var{m},@var{n}], @var{fun})
+## @deftypefnx {Function File} {@var{B} = } nlfilter (@var{A}, [@var{m},@var{n}], @var{fun}, ...)
+## @deftypefnx {Function File} {@var{B} = } nlfilter (@var{A},'indexed', ...)
+## Processes image in sliding blocks using user-supplied function.
+##
+## @code{B=nlfilter(A,[m,n],fun)} passes sliding @var{m}-by-@var{n}
+## blocks to user-supplied function @var{fun}. A block is build for
+## every pixel in @var{A}, such as it is centered within the block.
+## @var{fun} must return a scalar, and it is used to create matrix
+## @var{B}. @var{nlfilter} pads the @var{m}-by-@var{n} block at the
+## edges if necessary.
+##
+## Center of block is taken at ceil([@var{m},@var{n}]/2).
+##
+## @code{B=nlfilter(A,[m,n],fun,...)} behaves as described above but
+## passes extra parameters to function @var{fun}.
+##
+## @code{B=nlfilter(A,'indexed',...)} assumes that @var{A} is an indexed
+## image, so it pads the image using proper value: 0 for uint8 and
+## uint16 images and 1 for double images. Keep in mind that if 'indexed'
+## is not specified padding is always done using 0.
+##
+## @seealso{colfilt,blkproc,inline}
+## @end deftypefn
+
+## Author: Josep Mones i Teixidor <jmones@puntbarra.com>
+
+function B = nlfilter(A, varargin)
+ if(nargin<3)
+ error("nlfilter: invalid number of parameters.");
+ endif
+
+ ## check 'indexed' presence
+ indexed=false;
+ p=1;
+ if(ischar(varargin{1}) && strcmp(varargin{1}, "indexed"))
+ indexed=true;
+ p+=1;
+ if(isa(A,"uint8") || isa(A,"uint16"))
+ padval=0;
+ else
+ padval=1;
+ endif
+ else
+ padval=0;
+ endif
+
+ ## check [m,n]
+ if(!isvector(varargin{p}))
+ error("nlfilter: expected [m,n] but param is not a vector.");
+ endif
+ if(length(varargin{p})!=2)
+ error("nlfilter: expected [m,n] but param has wrong length.");
+ endif
+ sblk=varargin{p}(:);
+ p+=1;
+
+ ## check fun
+ ## TODO: add proper checks for this one
+ if(nargin<p)
+ error("nlfilter: required parameters haven't been supplied.");
+ endif
+ fun=varargin{p};
+
+ ## remaining params are params to fun
+ ## extra params are p+1:nargin-1
+
+ ## We take an easy approach... feel free to optimize it (coding this
+ ## in C++ would be a great idea).
+
+ ## Calculate center of block
+ c=ceil(sblk/2);
+
+ ## Pre-padding
+ prepad=c-ones(2,1);
+
+ ## Post-padding
+ postpad=sblk-c;
+
+ ## Save A size
+ as=size(A);
+
+ ## Pad data
+ if(all(prepad==postpad))
+ if(any(prepad>0))
+ A=padarray(A,prepad,padval,'both');
+ endif
+ else
+ if(any(prepad>0))
+ A=padarray(A,prepad,padval,'pre');
+ endif
+ if(any(postpad>0))
+ A=padarray(A,postpad,padval,'post');
+ endif
+ endif
+
+ ## calc end offsets
+ me=postpad(1)+prepad(1);
+ ne=postpad(2)+prepad(2);
+
+ ## We concatenate everything to preserve fun return type
+ for i=1:as(1)
+ r=feval(fun,A(i:i+me,1:1+ne),varargin{p+1:nargin-1});
+ for j=2:as(2)
+ r=horzcat(r,feval(fun,A(i:i+me,j:j+ne),varargin{p+1:nargin-1}));
+ endfor
+ if(i==1)
+ B=r;
+ else
+ B=vertcat(B,r);
+ endif
+ endfor
+
+endfunction
+
+%!demo
+%! nlfilter(eye(10),[3,3],inline("any(x(:)>0)","x"))
+%! # creates a "wide" diagonal
+
+%!assert(nlfilter(eye(4),[2,3],inline("sum(x(:))","x")),[2,2,1,0;1,2,2,1;0,1,2,2;0,0,1,1]);
+%!assert(nlfilter(eye(4),'indexed',[2,3],inline("sum(x(:))","x")),[4,2,1,2;3,2,2,3;2,1,2,4;4,3,4,5]);
+%!assert(nlfilter(eye(4),'indexed',[2,3],inline("sum(x(:))==y","x","y"),2),[0,1,0,1;0,1,1,0;1,0,1,0;0,0,0,0]!=0);
+
+% Check uint8 and uint16 padding
+%!assert(nlfilter(uint8(eye(4)),'indexed',[2,3],inline("sum(x(:))","x")),[2,2,1,0;1,2,2,1;0,1,2,2;0,0,1,1]);
+%!assert(nlfilter(uint16(eye(4)),'indexed',[2,3],inline("sum(x(:))","x")),[2,2,1,0;1,2,2,1;0,1,2,2;0,0,1,1]);
+
+% Check if function class is preserved
+%!assert(nlfilter(uint8(eye(4)),'indexed',[2,3],inline("int8(sum(x(:)))","x")),int8([2,2,1,0;1,2,2,1;0,1,2,2;0,0,1,1]));
+
+
+
+%
+% $Log$
+% Revision 1.4 2007/03/23 16:14:37 adb014
+% Update the FSF address
+%
+% Revision 1.3 2007/01/04 23:50:47 hauberg
+% Put seealso before end deftypefn
+%
+% Revision 1.2 2007/01/04 23:37:54 hauberg
+% Minor changes in help text
+%
+% Revision 1.1 2006/08/20 12:59:35 hauberg
+% Changed the structure to match the package system
+%
+% Revision 1.5 2005/09/08 02:00:17 pkienzle
+% [for Bill Denney] isstr -> ischar
+%
+% Revision 1.4 2004/11/15 16:04:20 pkienzle
+% Fix tests for functions which return boolean matrices
+%
+% Revision 1.3 2004/09/03 13:28:32 jmones
+% Corrected behaviour for int* and uint* types
+%
+% Revision 1.2 2004/08/15 19:43:11 jmones
+% corrected a typo in doc
+%
+% Revision 1.1 2004/08/15 19:42:14 jmones
+% nlfilter: Processes image in siliding blocks using user-supplied function
+%
+%
git://git.creatis.insa-lyon.fr / CreaPhase.git / blobdiff