## Copyright (C) 2005 Søren Hauberg ## ## This program is free software; you can redistribute it and/or modify ## it under the terms of the GNU General Public License as published by ## the Free Software Foundation; either version 2 of the License, or ## (at your option) any later version. ## ## This program is distributed in the hope that it will be useful, ## but WITHOUT ANY WARRANTY; without even the implied warranty of ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ## GNU General Public License for more details. ## ## You should have received a copy of the GNU General Public License ## along with this program; If not, see <http://www.gnu.org/licenses/>. ## -*- texinfo -*- ## @deftypefn {Function File} @var{total}= bwarea(@var{bw}) ## Estimates the area of the "on" pixels of @var{bw}. ## If @var{bw} is a binary image "on" pixels are defined as pixels ## valued 1. If @var{bw} is a grayscale image "on" pixels is defined ## as pixels with values larger than zero. ## This algorithm is not the same as counting the number of "on" ## pixels as it tries to estimate the area of the original object ## and not the image object. ## @end deftypefn ## Author: Søren Hauberg <hauberg at gmail dot com> ## ## 2005-06-05 Søren Hauberg <hauberg at gmail dot com> ## * Initial revision function total = bwarea(bw) if (isgray(bw)) bw = (bw > 0); endif if (!isbw(bw)) error("input image muste be either binary or gray scale.\n"); endif four = ones(2); two = diag([1 1]); fours = conv2(bw, four); twos = conv2(bw, two); nQ1 = sum(fours(:) == 1); nQ3 = sum(fours(:) == 3); nQ4 = sum(fours(:) == 4); nQD = sum(fours(:) == 2 & twos(:) != 1); nQ2 = sum(fours(:) == 2 & twos(:) == 1); total = 0.25*nQ1 + 0.5*nQ2 + 0.875*nQ3 + nQ4 + 0.75*nQD; endfunction

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