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1 ## Copyright (C) 2004 Josep Mones i Teixidor <jmones@puntbarra.com> |
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2 ## Copyright (C) 2008 Soren Hauberg <soren@hauberg.org> |
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3 ## Copyright (C) 2010 Carnë Draug <carandraug+dev@gmail.com> |
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4 ## |
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5 ## This program is free software; you can redistribute it and/or modify it under |
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6 ## the terms of the GNU General Public License as published by the Free Software |
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7 ## Foundation; either version 3 of the License, or (at your option) any later |
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8 ## version. |
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9 ## |
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10 ## This program is distributed in the hope that it will be useful, but WITHOUT |
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11 ## ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
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12 ## FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more |
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13 ## details. |
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14 ## |
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15 ## You should have received a copy of the GNU General Public License along with |
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16 ## this program; if not, see <http://www.gnu.org/licenses/>. |
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17 |
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18 ## -*- texinfo -*- |
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19 ## @deftypefn {Function File} {@var{B} =} imdilate (@var{A}, @var{se}) |
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20 ## Perform morphological dilation on a given image. |
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21 ## |
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22 ## The image @var{A} must be a grayscale or binary image, and @var{se} a |
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23 ## structuring element. Both must have the same class, e.g., if @var{A} is a |
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24 ## logical matrix, @var{se} must also be logical. Note that the erosion |
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25 ## algorithm is different for each class, being much faster for logical |
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26 ## matrices. As such, if you have a binary matrix, you should use @code{logical} |
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27 ## first. This will also reduce the memory usage of your code. |
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28 ## |
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29 ## The center of @var{SE} is calculated using floor((size(@var{SE})+1)/2). |
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30 ## |
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31 ## Pixels outside the image are considered to be 0. |
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32 ## |
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33 ## @seealso{imerode, imopen, imclose} |
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34 ## @end deftypefn |
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35 |
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36 function retval = imdilate(im, se) |
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37 ## Checkinput |
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38 if (nargin != 2) |
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39 print_usage(); |
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40 endif |
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41 if (!ismatrix(im) || !isreal(im)) |
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42 error("imdilate: first input argument must be a real matrix"); |
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43 elseif (!ismatrix(se) || !isreal(se)) |
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44 error("imdilate: second input argument must be a real matrix"); |
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45 elseif ( !strcmp(class(im), class(se)) ) |
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46 error("imdilate: image and structuring element must have the same class"); |
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47 endif |
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48 |
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49 ## Perform filtering |
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50 ## Filtering must be done with the reflection of the structuring element (they |
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51 ## are not always symmetrical) |
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52 se = imrotate(se, 180); |
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53 |
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54 ## If image is binary/logical, try to use filter2 (much faster) |
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55 if (islogical(im)) |
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56 retval = filter2(se,im)>0; |
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57 else |
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58 retval = ordfiltn(im, sum(se(:)!=0), se, 0); |
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59 endif |
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60 |
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61 endfunction |
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62 |
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63 %!demo |
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64 %! imdilate(eye(5),ones(2,2)) |
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65 %! % returns a thick diagonal. |
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66 |
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67 %!assert(imdilate(eye(3),[1])==eye(3)); # using [1] as a mask returns the same value |
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68 %!assert(imdilate(eye(3),[1,0,0])==[0,0,0;1,0,0;0,1,0]); # check if it works with non-symmetric SE |
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69 %!assert(imdilate(eye(5),[1,0,0,0])==[0,0,0,0,0;1,0,0,0,0;0,1,0,0,0;0,0,1,0,0;0,0,0,1,0]); # test if center is correctly calculated on even masks |
