1## Copyright (C) 2014 Carnë Draug <carandraug@octave.org> 2## 3## This program is free software; you can redistribute it and/or 4## modify it under the terms of the GNU General Public License as 5## published by the Free Software Foundation; either version 3 of the 6## License, or (at your option) any later version. 7## 8## This program is distributed in the hope that it will be useful, but 9## WITHOUT ANY WARRANTY; without even the implied warranty of 10## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU 11## General Public License for more details. 12## 13## You should have received a copy of the GNU General Public License 14## along with this program; if not, see 15## <http://www.gnu.org/licenses/>. 16 17## -*- texinfo -*- 18## @deftypefn {Function File} {} imregionalmax (@var{img}) 19## @deftypefnx {Function File} {} imregionalmax (@var{img}, @var{conn}) 20## Compute regional maxima. 21## 22## Returns a logical matrix, same size as the input @var{img}, with the 23## regional maxima. 24## 25## The optional argument @var{conn}, defines the connectivity. It can 26## be a scalar value or a boolean matrix (see @code{conndef} for details). 27## Defaults to @code{conndef (ndims (@var{img}), "maximal")} 28## 29## Regional maxima should not be mistaken with local maxima. Local maxima 30## are pixels whose value is greater or equal to all of its neighbors. 31## A regional maxima is the connected component of pixels whose values are 32## all higher than the neighborhood of the maxima (the connected component, 33## not its individual pixels). 34## All pixels belonging to a regional maximum are local maxima, but the 35## inverse is not true. 36## 37## @seealso{immaximas, imreconstruct, imregionalmin} 38## @end deftypefn 39 40function bw = imregionalmax (img, conn) 41 if (nargin < 1 || nargin > 2) 42 print_usage (); 43 endif 44 45 if (nargin < 2) 46 conn = conndef (ndims (img), "maximal"); 47 else 48 conn = conndef (conn); 49 endif 50 51 if (islogical (img)) 52 bw = img; 53 else 54 ## we could probably still make this more efficient 55 if (isfloat (img)) 56 recon = imreconstruct (img, img + __eps__ (img), conn); 57 else 58 recon = imreconstruct (img, img + 1, conn); 59 endif 60 bw = (recon == img); 61 endif 62endfunction 63 64%!test 65%! a = [ 66%! 7 3 9 3 10 3 67%! 4 2 3 10 1 3 68%! 1 4 6 9 4 10 69%! 8 7 9 3 4 8 70%! 5 9 3 3 8 9 71%! 3 6 9 4 1 10]; 72%! 73%! a4 = [ 74%! 1 0 1 0 1 0 75%! 0 0 0 1 0 0 76%! 0 0 0 0 0 1 77%! 1 0 1 0 0 0 78%! 0 1 0 0 0 0 79%! 0 0 1 0 0 1]; 80%! assert (imregionalmax (a, 4), logical (a4)) 81%! a8 = [ 82%! 1 0 0 0 1 0 83%! 0 0 0 1 0 0 84%! 0 0 0 0 0 1 85%! 0 0 0 0 0 0 86%! 0 0 0 0 0 0 87%! 0 0 0 0 0 1]; 88%! assert (imregionalmax (a, 8), logical (a8)) 89%! assert (imregionalmax (a), logical (a8)) 90 91%!test 92%! ## test float input images <bug #51724> 93%! im0 = peaks (); 94%! im1 = im0 ./ 100; 95%! max_pos_expected = [1000; 1214; 1691; 2353]; 96%! max0 = imregionalmax (im0); 97%! max0_pos = find (max0); 98%! max1 = imregionalmax (im1); 99%! assert (max1, max0) 100%! assert (max0_pos, max_pos_expected) 101