source: trunk/src/transform_field/ima_remove_background.m @ 810

Last change on this file since 810 was 810, checked in by g7moreau, 10 years ago
  • Add license
File size: 2.3 KB
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1% 'ima_remove_background': removes backgound from an image (using the local minimum)
2% requires the Matlab image processing toolbox
3%------------------------------------------------------------------------
4%%%%  Use the general syntax for transform fields with a single input %%%%
5% OUTPUT:
6% DataOut:   output field structure
7%
8%INPUT:
9% DataIn:  first input field structure
10
11%=======================================================================
12% Copyright 2008-2014, LEGI UMR 5519 / CNRS UJF G-INP, Grenoble, France
13%   http://www.legi.grenoble-inp.fr
14%   Joel.Sommeria - Joel.Sommeria (A) legi.cnrs.fr
15%
16%     This file is part of the toolbox UVMAT.
17%
18%     UVMAT is free software; you can redistribute it and/or modify
19%     it under the terms of the GNU General Public License as published
20%     by the Free Software Foundation; either version 2 of the license,
21%     or (at your option) any later version.
22%
23%     UVMAT is distributed in the hope that it will be useful,
24%     but WITHOUT ANY WARRANTY; without even the implied warranty of
25%     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
26%     GNU General Public License (see LICENSE.txt) for more details.
27%=======================================================================
28
29function DataOut=remove_background(DataIn)
30%------------------------------------------------------------------------
31DataOut=[];  %default  output field
32if strcmp(DataIn,'*')
33    return
34end
35
36%parameters
37threshold=200
38nblock_x=30;%size of image subblocks for analysis
39nblock_y=30;
40%---------------------------------------------------------
41DataOut=DataIn;%default
42
43%BACKGROUND LEVEL
44Atype=class(DataIn.A);
45A=double(DataIn.A);
46Backg=zeros(size(A));
47Aflagmin=sparse(imregionalmin(A));%Amin=1 for local image minima
48Amin=A.*Aflagmin;%values of A at local minima
49% local background: find all the local minima in image subblocks
50sumblock= inline('sum(sum(x(:)))');
51Backg=blkproc(Amin,[nblock_y nblock_x],sumblock);% take the sum in  blocks
52Bmin=blkproc(Aflagmin,[nblock_y nblock_x],sumblock);% find the number of minima in blocks
53Backg=Backg./Bmin; % find the average of minima in blocks
54B=imresize(Backg,size(A),'bilinear');% interpolate to the initial size image
55ImPart=(A-B);
56DataOut.A=ImPart.*(ImPart>threshold);
57DataOut.A=feval(Atype,DataOut.A);
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