Mercurial > octave
annotate scripts/image/cmunique.m @ 31218:a33a9c87220b stable
imformats.m: Fix "isa" function in return value (bug #62974)
* imformats.m (isa_magick): Fix typo "Format" to "format" for name of field in
struct returned from __magick_ping__.
| author | Rik <rik@octave.org> |
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| date | Tue, 30 Aug 2022 15:24:29 -0700 |
| parents | 796f54d4ddbf |
| children | 597f3ee61a48 |
| rev | line source |
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1 ######################################################################## |
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2 ## |
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3 ## Copyright (C) 2004-2022 The Octave Project Developers |
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4 ## |
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5 ## See the file COPYRIGHT.md in the top-level directory of this |
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6 ## distribution or <https://octave.org/copyright/>. |
| 14896 | 7 ## |
| 8 ## This file is part of Octave. | |
| 9 ## | |
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10 ## Octave is free software: you can redistribute it and/or modify it |
| 14896 | 11 ## under the terms of the GNU General Public License as published by |
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12 ## the Free Software Foundation, either version 3 of the License, or |
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13 ## (at your option) any later version. |
| 14896 | 14 ## |
| 15 ## Octave is distributed in the hope that it will be useful, but | |
| 16 ## WITHOUT ANY WARRANTY; without even the implied warranty of | |
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17 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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18 ## GNU General Public License for more details. |
| 14896 | 19 ## |
| 20 ## You should have received a copy of the GNU General Public License | |
| 21 ## along with Octave; see the file COPYING. If not, see | |
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22 ## <https://www.gnu.org/licenses/>. |
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23 ## |
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24 ######################################################################## |
| 14896 | 25 |
| 26 ## -*- texinfo -*- | |
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27 ## @deftypefn {} {[@var{Y}, @var{newmap}] =} cmunique (@var{X}, @var{map}) |
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28 ## @deftypefnx {} {[@var{Y}, @var{newmap}] =} cmunique (@var{RGB}) |
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29 ## @deftypefnx {} {[@var{Y}, @var{newmap}] =} cmunique (@var{I}) |
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30 ## Convert an input image @var{X} to an output indexed image @var{Y} which uses |
| 14896 | 31 ## the smallest colormap possible @var{newmap}. |
| 32 ## | |
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33 ## When the input is an indexed image (@var{X} with colormap @var{map}) the |
| 14896 | 34 ## output is a colormap @var{newmap} from which any repeated rows have been |
| 35 ## eliminated. The output image, @var{Y}, is the original input image with | |
| 36 ## the indices adjusted to match the new, possibly smaller, colormap. | |
| 37 ## | |
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38 ## When the input is an RGB image (an @nospell{MxNx3} array), the output |
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39 ## colormap will contain one entry for every unique color in the original |
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40 ## image. In the worst case the new map could have as many rows as the |
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41 ## number of pixels in the original image. |
| 14896 | 42 ## |
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43 ## When the input is a grayscale image @var{I}, the output colormap will |
| 14896 | 44 ## contain one entry for every unique intensity value in the original image. |
| 45 ## In the worst case the new map could have as many rows as the number of | |
| 46 ## pixels in the original image. | |
| 47 ## | |
| 48 ## Implementation Details: | |
| 49 ## | |
| 50 ## @var{newmap} is always an Mx3 matrix, even if the input image is | |
| 51 ## an intensity grayscale image @var{I} (all three RGB planes are | |
| 52 ## assigned the same value). | |
| 53 ## | |
| 54 ## The output image is of class uint8 if the size of the new colormap is | |
| 55 ## less than or equal to 256. Otherwise, the output image is of class double. | |
| 56 ## | |
| 57 ## @seealso{rgb2ind, gray2ind} | |
| 58 ## @end deftypefn | |
| 59 | |
| 60 | |
| 61 function [Y, newmap] = cmunique (X, map) | |
| 62 | |
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63 if (nargin < 1) |
| 14896 | 64 print_usage (); |
| 65 endif | |
| 66 | |
| 67 cls = class (X); | |
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68 if (! any (strcmp (cls, {"uint8", "uint16", "single", "double"}))) |
| 14896 | 69 error ("cmunique: X is of invalid data type '%s'", cls); |
| 70 endif | |
| 71 | |
| 72 if (nargin == 2) | |
| 73 ## (X, map) case | |
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74 if (! iscolormap (map) || min (map(:)) < 0 || max (map(:)) > 1) |
| 14896 | 75 error ("cmunique: MAP must be a valid colormap"); |
| 76 endif | |
| 77 [newmap,i,j] = unique (map, "rows"); # calculate unique colormap | |
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78 if (isfloat (X)) |
| 14896 | 79 Y = j(X); # find new indices |
| 80 else | |
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81 Y = j(double (X) + 1); # find new indices, switch to 1-based index |
| 14896 | 82 endif |
| 83 else | |
| 84 switch (size (X,3)) | |
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85 case 1 |
| 14896 | 86 ## I case |
| 87 [newmap,i,j] = unique (X); # calculate unique colormap | |
| 88 newmap = repmat (newmap,1,3); # get a RGB colormap | |
| 89 Y = reshape (j, rows (X), columns (X)); # Y is j reshaped | |
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90 case 3 |
| 14896 | 91 ## RGB case |
| 92 ## build a map with all values | |
| 93 map = [X(:,:,1)(:), X(:,:,2)(:), X(:,:,3)(:)]; | |
| 94 [newmap,i,j] = unique (map, "rows"); # calculate unique colormap | |
| 95 Y = reshape (j, rows (X), columns (X)); # Y is j reshaped | |
| 96 otherwise | |
| 97 error ("cmunique: X is not a valid image"); | |
| 98 endswitch | |
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99 |
| 14896 | 100 ## if image was uint8 or uint16 we have to convert newmap to [0,1] range |
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101 if (isinteger (X)) |
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102 newmap = double (newmap) / double (intmax (cls)); |
| 14896 | 103 endif |
| 104 endif | |
| 105 | |
| 106 if (rows (newmap) <= 256) | |
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107 ## convert Y to uint8 and 0-based indexing |
| 14896 | 108 Y = uint8 (Y-1); |
| 109 endif | |
| 110 | |
| 111 endfunction | |
| 112 | |
| 113 | |
| 114 %!demo | |
| 115 %! [Y, newmap] = cmunique ([1:4;5:8], [hot(4);hot(4)]) | |
| 116 %! ## Both rows are equal since map maps colors to the same value | |
| 117 %! ## cmunique will give the same indices to both | |
| 118 | |
| 119 ## Check that output is uint8 in short colormaps | |
| 120 %!test | |
| 121 %! [Y, newmap] = cmunique ([1:4;5:8], [hot(4);hot(4)]); | |
| 122 %! assert (Y, uint8 ([0:3;0:3])); | |
| 123 %! assert (newmap, hot (4)); | |
| 124 | |
| 125 ## Check that output is double in bigger | |
| 126 %!test | |
| 127 %! [Y, newmap] = cmunique ([1:300;301:600], [hot(300);hot(300)]); | |
| 128 %! assert (Y, [1:300;1:300]); | |
| 129 %! assert (newmap, hot (300)); | |
| 130 | |
| 131 ## Check boundary case 256 | |
| 132 %!test | |
| 133 %! [Y, newmap] = cmunique ([1:256;257:512], [hot(256);hot(256)]); | |
| 134 %! assert (Y, uint8 ([0:255;0:255])); | |
| 135 %! assert (newmap, hot (256)); | |
| 136 | |
| 137 ## Check boundary case 257 | |
| 138 %!test | |
| 139 %! [Y, newmap] = cmunique ([1:257;258:514], [hot(257);hot(257)]); | |
| 140 %! assert (Y, [1:257;1:257]); | |
| 141 %! assert (newmap, hot (257)); | |
| 142 | |
| 143 ## Random RGB image | |
| 144 %!test | |
| 145 %! RGB = rand (10,10,3); | |
| 146 %! [Y, newmap] = cmunique (RGB); | |
| 147 %! assert (RGB(:,:,1), newmap(:,1)(Y+1)); | |
| 148 %! assert (RGB(:,:,2), newmap(:,2)(Y+1)); | |
| 149 %! assert (RGB(:,:,3), newmap(:,3)(Y+1)); | |
| 150 | |
| 151 ## Random uint8 RGB image | |
| 152 %!test | |
| 153 %! RGB = uint8 (rand (10,10,3)*255); | |
| 154 %! RGBd = double (RGB) / 255; | |
| 155 %! [Y, newmap] = cmunique (RGB); | |
| 156 %! assert (RGBd(:,:,1), newmap(:,1)(Y+1)); | |
| 157 %! assert (RGBd(:,:,2), newmap(:,2)(Y+1)); | |
| 158 %! assert (RGBd(:,:,3), newmap(:,3)(Y+1)); | |
| 159 | |
| 160 ## Random uint16 RGB image | |
| 161 %!test | |
| 162 %! RGB = uint16 (rand (10,10,3)*65535); | |
| 163 %! RGBd = double (RGB) / 65535; | |
| 164 %! [Y, newmap] = cmunique (RGB); | |
| 165 %! assert (RGBd(:,:,1), newmap(:,1)(Y+1)); | |
| 166 %! assert (RGBd(:,:,2), newmap(:,2)(Y+1)); | |
| 167 %! assert (RGBd(:,:,3), newmap(:,3)(Y+1)); | |
| 168 | |
| 169 ## Random I image | |
| 170 %!test | |
| 171 %! I = rand (10,10); | |
| 172 %! [Y, newmap] = cmunique (I); | |
| 173 %! assert (I, newmap(:,1)(Y+1)); | |
| 174 %! assert (I, newmap(:,2)(Y+1)); | |
| 175 %! assert (I, newmap(:,3)(Y+1)); | |
| 176 | |
| 177 ## Random uint8 I image | |
| 178 %!test | |
| 179 %! I = uint8 (rand (10,10)*256); | |
| 180 %! Id = double (I) / 255; | |
| 181 %! [Y, newmap] = cmunique (I); | |
| 182 %! assert (Id, newmap(:,1)(Y+1)); | |
| 183 %! assert (Id, newmap(:,2)(Y+1)); | |
| 184 %! assert (Id, newmap(:,3)(Y+1)); | |
| 185 | |
| 186 ## Random uint16 I image | |
| 187 %!test | |
| 188 %! I = uint16 (rand (10,10)*65535); | |
| 189 %! Id = double (I) / 65535; | |
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190 %! [Y, newmap] = cmunique (I); |
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191 %! assert (Id, newmap(:,1)(Y+1)); |
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192 %! assert (Id, newmap(:,2)(Y+1)); |
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193 %! assert (Id, newmap(:,3)(Y+1)); |
| 14896 | 194 |
| 195 ## Test input validation | |
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196 %!error <Invalid call> cmunique () |
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197 %!error <X is of invalid data type> cmunique (uint32 (magic (16))) |
| 14896 | 198 %!error <MAP must be a valid colormap> cmunique (1, "a") |
| 199 %!error <MAP must be a valid colormap> cmunique (1, i) | |
| 200 %!error <MAP must be a valid colormap> cmunique (1, ones (3,3,3)) | |
| 201 %!error <MAP must be a valid colormap> cmunique (1, ones (3,2)) | |
| 202 %!error <MAP must be a valid colormap> cmunique (1, [-1 1 1]) | |
| 203 %!error <MAP must be a valid colormap> cmunique (1, [2 1 1]) |