[574] | 1 | % 'ima_remove_background': removes backgound from an image (using the local minimum)
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| 2 | % requires the Matlab image processing toolbox
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| 3 |
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| 4 | %------------------------------------------------------------------------
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| 5 | %%%% Use the general syntax for transform fields with a single input %%%%
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| 6 | % OUTPUT:
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| 7 | % DataOut: output field structure
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| 8 |
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| 9 | %INPUT:
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| 10 | % DataIn: first input field structure
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| 11 | %------------------------------------------------------------------------
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| 12 | function DataOut=remove_background(DataIn)
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| 13 | %------------------------------------------------------------------------
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| 14 | DataOut=[]; %default output field
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| 15 | if strcmp(DataIn,'*')
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| 16 | return
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| 17 | end
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| 18 |
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| 19 | %parameters
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| 20 | threshold=200
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| 21 | nblock_x=30;%size of image subblocks for analysis
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| 22 | nblock_y=30;
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| 23 | %---------------------------------------------------------
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| 24 | DataOut=DataIn;%default
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| 25 |
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| 26 | %BACKGROUND LEVEL
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| 27 | Atype=class(DataIn.A);
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| 28 | A=double(DataIn.A);
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| 29 | Backg=zeros(size(A));
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| 30 | Aflagmin=sparse(imregionalmin(A));%Amin=1 for local image minima
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| 31 | Amin=A.*Aflagmin;%values of A at local minima
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| 32 | % local background: find all the local minima in image subblocks
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| 33 | sumblock= inline('sum(sum(x(:)))');
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| 34 | Backg=blkproc(Amin,[nblock_y nblock_x],sumblock);% take the sum in blocks
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| 35 | Bmin=blkproc(Aflagmin,[nblock_y nblock_x],sumblock);% find the number of minima in blocks
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| 36 | Backg=Backg./Bmin; % find the average of minima in blocks
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| 37 | B=imresize(Backg,size(A),'bilinear');% interpolate to the initial size image
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| 38 | ImPart=(A-B);
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| 39 | DataOut.A=ImPart.*(ImPart>threshold);
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| 40 | DataOut.A=feval(Atype,DataOut.A); |
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