1 | % 'ima_remove_particles': removes particles from an image (keeping 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=ima_remove_particles(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 | if ~isfield(DataIn,'A')
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27 | DataOut.Txt='remove_particles only valid for input images';
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28 | return
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29 | end
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30 |
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31 | %BACKGROUND LEVEL
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32 | Atype=class(DataIn.A);
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33 | A=double(DataIn.A);
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34 | Backg=zeros(size(A));
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35 | Aflagmin=sparse(imregionalmin(A));%Amin=1 for local image minima
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36 | Amin=A.*Aflagmin;%values of A at local minima
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37 | % local background: find all the local minima in image subblocks
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38 | sumblock= inline('sum(sum(x(:)))');
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39 | Backg=blkproc(Amin,[nblock_y nblock_x],sumblock);% take the sum in blocks
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40 | Bmin=blkproc(Aflagmin,[nblock_y nblock_x],sumblock);% find the number of minima in blocks
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41 | Backg=Backg./Bmin; % find the average of minima in blocks
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42 | B=imresize(Backg,size(A),'bilinear');% interpolate to the initial size image
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43 | ImPart=(A-B);
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44 | ImPart=ImPart.*(ImPart>threshold);
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45 | DataOut.A=A-ImPart;%
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46 | DataOut.A=feval(Atype,DataOut.A);
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47 |
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