1 ## Copyright (C) 2000 Kai Habel
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{J} = histeq (@var{I}, @var{n})
18 ## Histogram equalization of a gray-scale image. The histogram contains
19 ## @var{n} bins, which defaults to 64.
21 ## @var{I}: Image in double format, with values from 0.0 to 1.0
23 ## @var{J}: Returned image, in double format as well
27 ## Author: Kai Habel <kai.habel@gmx.de>
28 ## Date: 08. August 2000
29 ## Modified-by: Jonas Wagner <j.b.w@gmx.ch>
30 ## Date: 11. February 2008
32 function J = histeq (I, n)
41 [X,map] = gray2ind(I, n);
42 [nn,xx] = imhist(I, n);
43 Icdf = 1 / prod(size(I)) * cumsum(nn);
44 J = reshape(Icdf(X),r,c);
46 legend( 'Image Cumulative Density Function');