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[project @ 2006-05-17 21:00:54 by jwe]
author jwe
date Wed, 17 May 2006 21:00:54 +0000
parents
children bd0507994409
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5820
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1 ## Copyright (C) 2001 Paul Kienzle
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2 ##
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3 ## This file is part of Octave.
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4 ##
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5 ## Octave is free software; you can redistribute it and/or modify it
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6 ## under the terms of the GNU General Public License as published by
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7 ## the Free Software Foundation; either version 2, or (at your option)
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8 ## any later version.
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9 ##
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10 ## Octave is distributed in the hope that it will be useful, but
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11 ## WITHOUT ANY WARRANTY; without even the implied warranty of
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12 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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13 ## General Public License for more details.
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14 ##
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15 ## You should have received a copy of the GNU General Public License
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16 ## along with Octave; see the file COPYING. If not, write to the Free
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17 ## Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
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18 ## 02110-1301, USA.
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19
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20 ## @deftypefn {Function File} {@var{y} =} filter2 (@var{b, @var{x}})
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21 ## @deftypefnx {Function File} {@var{y} =} filter2 (@var{b, @var{x}}, @var{shape})
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22 ## Apply the 2-D FIR filter @var{b} to @var{x}. If the argument
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23 ## @var{shape} is specified, return an array of the desired shape.
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24 ## Possible values are:
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25 ##
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26 ## @table @asis
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27 ## @item 'full'
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28 ## pad @var{x} with zeros on all sides before filtering.
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29 ## @item 'same'
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30 ## unpadded @var{x} (default)
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31 ## @item 'valid'
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32 ## trim @var{x} after filtering so edge effects are no included.
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33 ## @end table
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34 ##
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35 ## Note this is just a variation on convolution, with the parameters
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36 ## reversed and @var{b} rotated 180 degrees.
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37 ## @seealso{conv2}
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38 ## @end{deftypefn}
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39
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40 ## Author: Paul Kienzle <pkienzle@users.sf.net>
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41 ## 2001-02-08
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42 ## * initial release
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43
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44 function Y = filter2 (B, X, shape)
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45
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46 if (nargin < 2 || nargin > 3)
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47 usage ("Y = filter2 (B, X [, 'shape'])");
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48 endif
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49 if (nargin < 3)
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50 shape = "same";
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51 endif
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52
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53 [nr, nc] = size(B);
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54 Y = conv2 (X, B(nr:-1:1, nc:-1:1), shape);
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55 endfunction