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annotate scripts/image/gray2ind.m @ 15690:7d21456c09d1

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gray2ind: also accept binary images and default n to 2 in such cases
author Carnë Draug <carandraug+dev@gmail.com>
date Mon, 12 Nov 2012 05:25:37 +0000
parents 5d3a684236b0
children dffb28f47ea8
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72c96de7a403 maint: update copyright notices for 2012
John W. Eaton <jwe@octave.org>
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1 ## Copyright (C) 1994-2012 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{img} =} gray2ind (@var{I})
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21 ## @deftypefnx {Function File} {[@var{img} =} gray2ind (@var{I}, @var{n})
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22 ## @deftypefnx {Function File} {[@var{img}, @var{map} =} gray2ind (@dots{})
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23 ## Convert a gray scale or binary image to an indexed image.
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24 ##
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25 ## The indexed image will consist of @var{n} different intensity values.
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26 ## If not given @var{n} defaults to 64 and 2 for gray scale and binary images
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27 ## respectively.
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28 ## @seealso{ind2gray, rgb2ind}
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29 ## @end deftypefn
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31 ## Author: Tony Richardson <arichard@stark.cc.oh.us>
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32 ## Created: July 1994
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33 ## Adapted-By: jwe
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35 function [X, map] = gray2ind (I, n = 64)
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36 ## Check input
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37 if (nargin < 1 || nargin > 2)
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38 print_usage ();
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39 endif
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40
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41 ## default n is different if image is logical
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42 if (nargin < 2 && isa (I, "logical"))
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43 n = 2;
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44 endif
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45
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46 C = class (I);
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47 if (! ismatrix (I) || ndims (I) != 2)
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48 error ("gray2ind: first input argument must be a gray scale image");
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49 endif
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50 if (! isscalar (n) || n < 0)
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51 error ("gray2ind: second input argument must be a positive integer");
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52 endif
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53 ints = {"uint8", "uint16", "int8", "int16"};
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54 floats = {"double", "single"};
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55 if (! ismember (C, {ints{:}, floats{:}, "logical"}))
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56 error ("gray2ind: invalid data type '%s'", C);
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57 endif
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58 if (ismember (C, floats) && (min (I(:)) < 0 || max (I(:)) > 1))
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59 error ("gray2ind: floating point images may only contain values between 0 and 1");
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60 endif
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61
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62 ## Convert data
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63 map = gray (n);
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64 ## If @var{I} is an integer matrix convert it to a double matrix with values in [0, 1]
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65 if (ismember (C, ints))
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66 low = double (intmin (C));
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67 high = double (intmax (C));
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68 I = (double (I) - low) / (high - low);
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69 endif
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70 X = round (I*(n-1)) + 1;
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72 endfunction