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1 ## Copyright (C) 2010 Soren Hauberg |
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2 ## |
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3 ## This program is free software; you can redistribute it and/or modify |
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4 ## it under the terms of the GNU General Public License as published by |
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5 ## the Free Software Foundation; either version 3 of the License, or |
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6 ## (at your option) any later version. |
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7 ## |
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8 ## This program is distributed in the hope that it will be useful, |
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9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of |
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10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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11 ## GNU General Public License for more details. |
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12 ## |
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13 ## You should have received a copy of the GNU General Public License |
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14 ## along with this program; If not, see <http://www.gnu.org/licenses/>. |
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15 |
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16 ## -*- texinfo -*- |
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17 ## @deftypefn {Function File} {@var{props} = } regionprops (@var{BW}) |
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18 ## @deftypefnx {Function File} {@var{props} = } regionprops (@var{BW}, @var{properties}, @dots{}) |
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19 ## Compute object properties in a binary image. |
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20 ## |
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21 ## @code{regionprops} computes various properties of the individual objects (as |
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22 ## identified by @code{bwlabel}) in the binary image @var{BW}. The result is a |
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23 ## structure array containing an entry per property per object. |
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24 ## |
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25 ## The following properties can be computed. |
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26 ## |
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27 ## @table @t |
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28 ## @item "Area" |
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29 ## The number of pixels in the object. |
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30 ## @item "EulerNumber" |
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31 ## @itemx "euler_number" |
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32 ## The Euler number of the object (see @code{bweuler} for details). |
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33 ## @item "BoundingBox" |
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34 ## @itemx "bounding_box" |
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35 ## The bounding box of the object. This is represented as a 4-vector where the |
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36 ## first two entries are the @math{x} and @math{y} coordinates of the upper left |
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37 ## corner of the bounding box, and the two last entries are the width and the |
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38 ## height of the box. |
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39 ## @item "Extent" |
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40 ## The area of the object divided by the area of the bounding box. |
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41 ## @item "Perimeter" |
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42 ## The length of the boundary of the object. |
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43 ## @item "Centroid" |
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44 ## The center coordinate of the object. |
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45 ## @item "PixelIdxList" |
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46 ## @itemx "pixel_idx_list" |
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47 ## The indices of the pixels in the object. |
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48 ## @item "FilledArea" |
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49 ## @itemx "filled_area" |
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50 ## The area of the object including possible holes. |
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51 ## @item "PixelList" |
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52 ## @itemx "pixel_list" |
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53 ## The actual pixel values inside the object. This is only useful for grey scale |
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54 ## images. |
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55 ## @item "FilledImage" |
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56 ## @itemx "filled_image" |
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57 ## A binary image with the same size as the object's bounding box that contains |
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58 ## the object with all holes removed. |
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59 ## @item "Image" |
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60 ## An image with the same size as the bounding box that contains the original pixels. |
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61 ## @item "MaxIntensity" |
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62 ## @itemx "max_intensity" |
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63 ## The maximum intensity inside the object. |
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64 ## @item "MinIntensity" |
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65 ## @itemx "min_intensity" |
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66 ## The minimum intensity inside the object. |
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67 ## @item "WeightedCentroid" |
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68 ## @itemx "weighted_centroid" |
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69 ## The centroid of the object where pixel values are used as weights. |
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70 ## @item "MeanIntensity" |
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71 ## @itemx "mean_intensity" |
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72 ## The mean intensity inside the object. |
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73 ## @item "PixelValues" |
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74 ## @itemx "pixel_values" |
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75 ## The pixel values inside the object represented as a vector. |
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76 ## @end table |
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77 ## |
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78 ## The requested properties can either be specified as several input arguments |
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79 ## or as a cell array of strings. As a short-hand it is also possible to give |
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80 ## the following strings as arguments. |
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81 ## |
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82 ## @table @t |
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83 ## @item "basic" |
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84 ## The following properties are computed: @t{"Area"}, @t{"Centroid"} and @t{"BoundingBox"}. |
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85 ## @item "all" |
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86 ## All properties are computed. |
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87 ## @end table |
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88 ## |
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89 ## If no properties are given, @t{basic} is assumed. |
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90 ## @seealso{bwlabel, bwperim, bweuler} |
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91 ## @end deftypefn |
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92 |
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93 function retval = regionprops (bw, varargin) |
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94 ## Check input |
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95 if (nargin < 1) |
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96 error ("regionprops: not enough input arguments"); |
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97 endif |
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98 |
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99 if (!ismatrix (bw) || ndims (bw) != 2) |
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100 error ("regionprops: first input argument must be a NxM matrix"); |
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101 endif |
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102 |
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103 if (numel (varargin) == 0) |
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104 properties = "basic"; |
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105 elseif (numel (varargin) == 1 && iscellstr (varargin {1})) |
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106 properties = varargin {1}; |
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107 elseif (iscellstr (varargin)) |
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108 properties = varargin; |
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109 else |
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110 error ("regionprops: properties must be a cell array of strings"); |
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111 endif |
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112 |
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113 if (ischar (properties) && strcmpi (properties, "basic")) |
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114 properties = {"Area", "Centroid", "BoundingBox"}; |
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115 elseif (ischar (properties) && strcmpi (properties, "all")) |
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116 properties = {"area", "eulernumber", "boundingbox", "extent", "perimeter", ... |
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117 "centroid", "pixelidxlist", "filledarea", "pixellist", ... |
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118 "filledimage", "image", "maxintensity", "minintensity", ... |
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119 "weightedcentroid", "meanintensity", "pixelvalues"}; |
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120 elseif (!iscellstr (properties)) |
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121 error ("%s %s", "regionprops: properties must be specified as a list of", |
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122 "strings or a cell array of strings"); |
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123 endif |
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124 |
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125 ## Get a labelled image |
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126 if (!islogical (bw) && all (bw >= 0) && all (bw == round (bw))) |
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127 L = bw; # the image was already labelled |
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128 num_labels = max (L (:)); |
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129 else |
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130 [L, num_labels] = bwlabel (bw); |
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131 endif |
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132 |
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133 ## Compute the properties |
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134 retval = struct (); |
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135 for k = 1:numel (properties) |
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136 switch (lower (properties {k})) |
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137 case "area" |
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138 for k = 1:num_labels |
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139 retval (k).Area = local_area (L == k); |
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140 endfor |
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141 |
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142 case {"eulernumber", "euler_number"} |
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143 for k = 1:num_labels |
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144 retval (k).EulerNumber = bweuler (L == k); |
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145 endfor |
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146 |
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147 case {"boundingbox", "bounding_box"} |
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148 for k = 1:num_labels |
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149 retval (k).BoundingBox = local_boundingbox (L == k); |
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150 endfor |
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151 |
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152 case "extent" |
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153 for k = 1:num_labels |
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154 bb = local_boundingbox (L == k); |
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155 area = local_area (L == k); |
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156 retval (k).Extent = area / (bb (3) * bb (4)); |
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157 endfor |
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158 |
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159 case "perimeter" |
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160 for k = 1:num_labels |
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161 retval (k).Perimeter = sum (bwperim (L == k) (:)); |
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162 endfor |
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163 |
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164 case "centroid" |
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165 for k = 1:num_labels |
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166 [Y, X] = find (L == k); |
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167 retval (k).Centroid = [mean(X), mean(Y)]; |
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168 endfor |
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169 |
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170 case {"pixelidxlist", "pixel_idx_list"} |
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171 for k = 1:num_labels |
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172 retval (k).PixelIdxList = find (L == k); |
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173 endfor |
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174 |
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175 case {"filledarea", "filled_area"} |
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176 for k = 1:num_labels |
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177 retval (k).FilledArea = sum (bwfill (L == k, "holes") (:)); |
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178 endfor |
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179 |
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180 case {"pixellist", "pixel_list"} |
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181 for k = 1:num_labels |
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182 [Y, X] = find (L == k); |
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183 retval (k).PixelList = [X, Y]; |
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184 endfor |
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185 |
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186 case {"filledimage", "filled_image"} |
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187 for k = 1:num_labels |
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188 retval (k).FilledImage = bwfill (L == k, "holes"); |
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189 endfor |
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190 |
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191 case "image" |
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192 for k = 1:num_labels |
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193 tmp = (L == k); |
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194 [R, C] = find (tmp); |
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195 retval (k).Image = tmp (min (R):max (R), min (C):max (C)); |
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196 endfor |
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197 |
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198 case {"maxintensity", "max_intensity"} |
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199 for k = 1:num_labels |
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200 retval (k).MaxIntensity = max (bw (L == k) (:)); |
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201 endfor |
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202 |
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203 case {"minintensity", "min_intensity"} |
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204 for k = 1:num_labels |
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205 retval (k).MaxIntensity = min (bw (L == k) (:)); |
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206 endfor |
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207 |
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208 case {"weightedcentroid", "weighted_centroid"} |
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209 for k = 1:num_labels |
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210 [Y, X] = find (L == k); |
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211 vals = bw (L == k) (:); |
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212 vals /= sum (vals); |
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213 retval (k).WeightedCentroid = [dot(X, vals), dot(Y, vals)]; |
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214 endfor |
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215 |
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216 case {"meanintensity", "mean_intensity"} |
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217 for k = 1:num_labels |
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218 retval (k).MaxIntensity = mean (bw (L == k) (:)); |
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219 endfor |
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220 |
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221 case {"pixelvalues", "pixel_values"} |
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222 for k = 1:num_labels |
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223 retval (k).PixelValues = bw (L == k)(:); |
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224 endfor |
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225 |
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226 case "orientation" |
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227 for k = 1:num_labels |
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228 [Y, X] = find (L == k); |
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229 if (numel (Y) > 1) |
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230 C = cov ([X(:), Y(:)]); |
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231 [V, lambda] = eig (C); |
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232 [max_val, max_idx] = max (diag (lambda)); |
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233 v = V (:, max_idx); |
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234 retval (k).Orientation = 180 - 180 * atan2 (v (2), v (1)) / pi; |
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235 else |
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236 retval (k).Orientation = 0; # XXX: What does the other brand do? |
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237 endif |
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238 endfor |
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239 |
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240 %{ |
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241 case "majoraxislength" |
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242 for k = 1:num_labels |
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243 [Y, X] = find (L == k); |
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244 if (numel (Y) > 1) |
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245 C = cov ([X(:), Y(:)]); |
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246 lambda = eig (C); |
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247 retval (k).MajorAxisLength = (max (lambda)); |
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248 else |
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249 retval (k).MajorAxisLength = 1; |
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250 endif |
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251 endfor |
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252 |
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253 case "minoraxislength" |
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254 for k = 1:num_labels |
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255 [Y, X] = find (L == k); |
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256 if (numel (Y) > 1) |
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257 C = cov ([X(:), Y(:)]); |
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258 lambda = eig (C); |
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259 retval (k).MinorAxisLength = (min (lambda)); |
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260 else |
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261 retval (k).MinorAxisLength = 1; |
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262 endif |
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263 endfor |
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264 %} |
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265 |
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266 #case "extrema" |
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267 #case "convexarea" |
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268 #case "convexhull" |
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269 #case "solidity" |
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270 #case "conveximage" |
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271 #case "subarrayidx" |
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272 #case "eccentricity" |
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273 #case "equivdiameter" |
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274 |
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275 otherwise |
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276 error ("regionprops: unsupported property '%s'", properties {k}); |
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277 endswitch |
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278 endfor |
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279 endfunction |
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280 |
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281 function retval = local_area (bw) |
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282 retval = sum (bw (:)); |
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283 endfunction |
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284 |
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285 function retval = local_boundingbox (bw) |
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286 [Y, X] = find (bw); |
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287 retval = [min(X)-0.5, min(Y)-0.5, max(X)-min(X)+1, max(Y)-min(Y)+1]; |
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288 endfunction |
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289 |
