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1 ## Copyright (C) 1996, 1997 John W. Eaton |
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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 3 of the License, or (at |
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8 ## your option) 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, see |
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17 ## <http://www.gnu.org/licenses/>. |
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18 |
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19 ## -*- texinfo -*- |
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20 ## @deftypefn {Function File} {@var{rgb} =} ind2rgb (@var{x}, @var{map}) |
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21 ## @deftypefnx {Function File} {[@var{r}, @var{g}, @var{b}] =} ind2rgb (@var{x}, @var{map}) |
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22 ## Convert an indexed image to red, green, and blue color components. |
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23 ## If the colormap doesn't contain enough colors, pad it with the |
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24 ## last color in the map. |
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25 ## If @var{map} is omitted, the current colormap is used for the conversion. |
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26 ## @seealso{rgb2ind, image, imshow, ind2gray, gray2ind} |
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27 ## @end deftypefn |
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28 |
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29 ## Author: Tony Richardson <arichard@stark.cc.oh.us> |
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30 ## Created: July 1994 |
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31 ## Adapted-By: jwe |
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32 |
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33 function [R, G, B] = ind2rgb (X, map) |
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34 |
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35 ## Do we have the right number of inputs? |
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36 if (nargin < 1 || nargin > 2) |
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37 print_usage (); |
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38 elseif (nargin == 1) |
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39 map = colormap (); |
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40 endif |
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41 |
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42 ## Check if X is an indexed image. |
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43 if (ndims (X) != 2 || any (X(:) != round (X(:))) || min (X(:)) < 1) |
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44 error ("ind2rgb: first input argument must be an indexed image"); |
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45 endif |
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46 |
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47 ## Check the color map. |
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48 if (ndims (map) != 2 || columns (map) != 3) |
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49 error ("ind2rgb: second input argument must be a color map"); |
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50 endif |
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51 |
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52 ## Do we have enough colors in the color map? |
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53 maxidx = max (X(:)); |
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54 rm = rows (map); |
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55 if (rm < maxidx) |
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56 ## Pad with the last color in the map. |
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57 pad = repmat (map(end,:), maxidx-rm, 1); |
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58 map(end+1:maxidx, :) = pad; |
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59 endif |
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60 |
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61 ## Compute result |
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62 [hi, wi] = size (X); |
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63 R = reshape (map (X(:), 1), hi, wi); |
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64 G = reshape (map (X(:), 2), hi, wi); |
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65 B = reshape (map (X(:), 3), hi, wi); |
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66 |
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67 ## Use 3D array if only one output is requested. |
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68 if (nargout <= 1) |
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69 R(:,:,3) = B; |
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70 R(:,:,2) = G; |
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71 endif |
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72 endfunction |
