Mercurial > hg > octave-image
annotate inst/isbw.m @ 507:a60411e31d36
isbw: check sample of image first to speed up computation
| author | carandraug |
|---|---|
| date | Mon, 05 Dec 2011 03:59:44 +0000 |
| parents | 5dd8356bd17c |
| children | 9135e5461550 |
| rev | line source |
|---|---|
| 502 | 1 ## Copyright (C) 2000 Kai Habel <kai.habel@gmx.de> |
| 2 ## Copyright (C) 2011 Carnë Draug <carandraug+dev@gmail.com> | |
| 186 | 3 ## |
| 4 ## This program is free software; you can redistribute it and/or modify | |
| 5 ## it under the terms of the GNU General Public License as published by | |
| 502 | 6 ## the Free Software Foundation; either version 3 of the License, or |
| 186 | 7 ## (at your option) any later version. |
| 8 ## | |
| 9 ## This program is distributed in the hope that it will be useful, | |
| 10 ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 11 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 12 ## GNU General Public License for more details. | |
| 13 ## | |
| 14 ## You should have received a copy of the GNU General Public License | |
| 274 | 15 ## along with this program; If not, see <http://www.gnu.org/licenses/>. |
| 186 | 16 |
| 17 ## -*- texinfo -*- | |
| 502 | 18 ## @deftypefn {Function File} @var{bool} = isbw (@var{img}) |
| 19 ## @deftypefnx {Function File} @var{bool} = isbw (@var{img}, @var{logic}) | |
| 20 ## Return true if @var{img} is a black-white image. | |
| 21 ## | |
| 22 ## The optional argument @var{logic} must be the string `logical' or | |
| 23 ## `non-logical'. The first defines a black and white image as a logical matrix, | |
| 24 ## while the second defines it as a matrix comprised of the values 1 and 0 | |
| 25 ## only. Defaults to `logical'. | |
| 26 ## | |
| 27 ## @seealso{isgray, isind, islogical, isrgb} | |
| 186 | 28 ## @end deftypefn |
| 29 | |
| 502 | 30 function bool = isbw (BW, logic = "logical") |
| 31 ## this function has been removed from version 7.3 (R2011b) of | |
| 32 ## matlab's image processing toolbox | |
| 33 if (nargin < 1 || nargin > 2) | |
| 34 print_usage; | |
| 35 elseif (!ischar (logic) && any (strcmpi (logic, {"logical", "non-logical"}))) | |
| 36 error ("second argument must either be a string 'logical' or 'non-logical'") | |
| 186 | 37 endif |
| 38 | |
| 502 | 39 ## an image cannot be a sparse matrix |
| 40 if (!ismatrix (BW) || issparse (BW)) | |
| 41 bool = false; | |
| 42 elseif (strcmpi (logic, "logical")) | |
| 43 ## this is the matlab compatible way (before they removed the function) | |
| 44 bool = islogical (BW); | |
| 186 | 45 |
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46 ## the following block is just temporary to keep backwards compatibility |
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47 if (!islogical (BW) && is_bw_nonlogical (BW)) |
| 502 | 48 persistent warned = false; |
| 49 if (! warned) | |
| 50 warned = true; | |
| 51 warning ("isbw: image is not logical matrix and therefore not binary but all values are either 0 and 1.") | |
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52 warning ("isbw: future versions of this function will return true. Consider using the call isbw (img, \"non-logical\").") |
| 502 | 53 endif |
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carandraug
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changeset
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54 bool = true; |
| 502 | 55 endif |
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carandraug
parents:
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changeset
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56 ## end of temporary block for backwards compatibility |
| 186 | 57 |
| 502 | 58 elseif (strcmpi (logic, "non-logical")) |
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59 ## to speed this up, we can look at a sample of the image first |
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60 bool = is_bw_nonlogical (BW(1:ceil (rows (BW) /100), 1:ceil (columns (BW) /100))); |
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61 if (bool) |
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62 ## sample was true, we better make sure it's real |
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63 bool = is_bw_nonlogical (BW); |
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64 endif |
| 502 | 65 endif |
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66 |
| 186 | 67 endfunction |
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68 |
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69 function bool = is_bw_nonlogical (BW) |
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70 bool = all (all ((BW == 1) + (BW == 0))); |
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71 endfunction |