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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 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, 59 Temple Place - Suite 330, Boston, MA |
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18 ## 02111-1307, USA. |
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19 |
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20 ## Convert an octave indexed image to a gray scale intensity image. |
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21 ## |
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22 ## Y = ind2gray (X) converts an indexed image to a gray scale intensity |
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23 ## image. The current colormap is used to determine the intensities. |
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24 ## The intensity values lie between 0 and 1 inclusive. |
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25 ## |
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26 ## Y = ind2gray (X, map) uses the specified colormap instead of the |
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27 ## current one in the conversion process. |
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28 ## |
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29 ## SEE ALSO: gray2ind, rgb2ntsc, image, colormap |
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30 |
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31 ## Author: Tony Richardson <amr@mpl.ucsd.edu> |
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32 ## Created: July 1994 |
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33 ## Adapted-By: jwe |
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34 |
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35 function Y = ind2gray (X, map) |
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36 |
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37 if (nargin < 1 || nargin > 2) |
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38 usage ("ind2gray (X, map)"); |
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39 elseif (nargin == 1) |
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40 map = colormap (); |
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41 endif |
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42 |
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43 ## Convert colormap to intensity values. |
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44 |
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45 yiq = rgb2ntsc (map); |
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46 y = yiq(:,1); |
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47 |
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48 ## We need Fortran indexing capability, but be sure to save the user's |
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49 ## preference. |
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50 |
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51 pref = do_fortran_indexing; |
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52 |
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53 unwind_protect |
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54 |
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55 do_fortran_indexing = 1; |
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56 |
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57 ## Replace indices in the input matrix with indexed values in the output |
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58 ## matrix. |
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559
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59 |
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60 [rows, cols] = size (X); |
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61 Y = y(X(:)); |
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62 Y = reshape (Y, rows, cols); |
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63 |
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64 unwind_protect_cleanup |
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65 do_fortran_indexing = pref; |
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66 end_unwind_protect |
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67 |
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68 endfunction |
