1 ## Copyright (C) 2005 Søren Hauberg
3 ## This program is free software; you can redistribute it and/or modify
4 ## it under the terms of the GNU General Public License as published by
5 ## the Free Software Foundation; either version 2 of the License, or
6 ## (at your option) any later version.
8 ## This program is distributed in the hope that it will be useful,
9 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
10 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
11 ## GNU General Public License for more details.
13 ## You should have received a copy of the GNU General Public License
14 ## along with this program; If not, see <http://www.gnu.org/licenses/>.
17 ## @deftypefn {Function File} @var{total}= bwarea(@var{bw})
18 ## Estimates the area of the "on" pixels of @var{bw}.
19 ## If @var{bw} is a binary image "on" pixels are defined as pixels
20 ## valued 1. If @var{bw} is a grayscale image "on" pixels is defined
21 ## as pixels with values larger than zero.
22 ## This algorithm is not the same as counting the number of "on"
23 ## pixels as it tries to estimate the area of the original object
24 ## and not the image object.
27 ## Author: Søren Hauberg <hauberg at gmail dot com>
29 ## 2005-06-05 Søren Hauberg <hauberg at gmail dot com>
33 function total = bwarea(bw)
39 error("input image muste be either binary or gray scale.\n");
45 fours = conv2(bw, four);
46 twos = conv2(bw, two);
48 nQ1 = sum(fours(:) == 1);
49 nQ3 = sum(fours(:) == 3);
50 nQ4 = sum(fours(:) == 4);
51 nQD = sum(fours(:) == 2 & twos(:) != 1);
52 nQ2 = sum(fours(:) == 2 & twos(:) == 1);
54 total = 0.25*nQ1 + 0.5*nQ2 + 0.875*nQ3 + nQ4 + 0.75*nQD;