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[07d29c]: grayslice.m Maximize Restore History

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grayslice.m    79 lines (66 with data), 2.1 kB

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## Copyright (C) 2000 Kai Habel
##
## 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, write to the Free Software
## Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
## -*- texinfo -*-
## @deftypefn {Function File} {@var{X} =} grayslice (@var{I},@var{n})
## @deftypefnx {Function File} {@var{X} =} grayslice (@var{I},@var{v})
## creates an indexed image @var{X} from an intensitiy image @var{I}
## using multiple threshold levels.
## A scalar integer value @var{n} sets the levels to
## @example
##
## @group
## 1 2 n-1
## -, -, ..., ---
## n n n
## @end group
## @end example
##
## X = grayslice(I,5);
##
## For irregular threshold values a real vector @var{v} can be used.
## The values must be in the range [0,1].
##
## @group
## X = grayslice(I,[0.1,0.33,0.75,0.9])
## @end group
##
## @end deftypefn
## @seealso{im2bw}
## Author: Kai Habel <kai.habel@gmx.de>
## Date: 03. August 2000
function X = grayslice (I, v)
if (nargin != 2)
usage ("grayslice(...) number of arguments must be 1 or 2");
endif
if (is_scalar(v) && (fix(v) == v))
v = (1:v - 1) / v;
elseif (isvector(v))
if (any (v < 0) || (any (v > 1)))
error ("slice vector must be in range [0,1]")
endif
v = [0,v,1];
else
usage("second argument");
endif
[r, c] = size (I);
[m, n] = sort ([v(:); I(:)]);
lx = length (v);
o = cumsum (n <= lx);
idx = o (find(n>lx));
[m, n] = sort (I(:));
[m, n] = sort (n);
X = reshape (idx(n), r, c);
endfunction