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[project @ 1995-01-11 20:30:04 by jwe]
author jwe
date Wed, 11 Jan 1995 20:30:04 +0000
parents b843a65fa977
children 611d403c7f3d
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1 # Copyright (C) 1995 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 the
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7 # Free Software Foundation; either version 2, or (at your option) any
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8 # later version.
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9 #
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10 # Octave 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
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13 # 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, 675 Mass Ave, Cambridge, MA 02139, USA.
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18
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19 function Y = ind2gray (X, map)
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20
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21 # Convert an octave indexed image to a gray scale intensity image.
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22 #
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23 # Y = ind2gray (X) converts an indexed image to a gray scale intensity
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24 # image. The current colormap is used to determine the intensities.
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25 # The intensity values lie between 0 and 1 inclusive.
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26 #
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27 # Y = ind2gray (X, map) uses the specified colormap instead of the
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28 # current one in the conversion process.
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29 #
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30 # SEE ALSO: gray2ind, rgb2ntsc, image, colormap
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31
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32 # Written by Tony Richardson (amr@mpl.ucsd.edu) July 1994.
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33
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34 if (nargin < 1 || nargin > 2)
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35 usage ("ind2gray (X, map)");
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36 elseif (nargin == 1)
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37 map = colormap ();
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38 endif
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39
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40 # Convert colormap to intensity values.
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41
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42 yiq = rgb2ntsc (map);
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43 y = yiq(:,1);
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44
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45 # We need Fortran indexing capability, but be sure to save the user's
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46 # preference.
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47
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48 pref = do_fortran_indexing;
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49
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50 unwind_protect
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51
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52 do_fortran_indexing = "true";
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53
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54 # Replace indices in the input matrix with indexed values in the output
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55 # matrix.
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56
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57 [rows, cols] = size (X);
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58 Y = y(X(:));
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59 Y = reshape (Y, rows, cols);
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60
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61 unwind_protect_cleanup
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62 do_fortran_indexing = pref;
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63 end_unwind_protect
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64
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65 endfunction