1 | %'hist_update': update of a current global histogram by inclusion of a new field
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2 | %------------------------------------------------------------------------
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3 | %[val,HIST]=hist_update(val,HIST,C,dC)
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4 | %
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5 | % OUTPUT:
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6 | % val: vector of field values at which the histogram is determined (middle of bins)
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7 | % HIST(:,icolor): nbre of occurence of the field value in the bins whose middle is given by val
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8 | % can be a column vector, same size as val, or a matrix with three columns, for color images
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9 | %
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10 | % INPUT:
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11 | % val: existing field values from the current histogram, =[] if there is no current histogram
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12 | % HIST(:,icolor): current histogram, =[] if there is none
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13 | % can be a column vector (icolor=1), same size as val, or a matrix with three columns, for color images
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14 | % C(:,icolor): vector representing the current field values
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15 | % can be a column vector (icolor=1), or a matrix with three columns, for color images
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16 | % dC: width of the new bins extending val to account for the new field.
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17 |
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18 | function [val,HIST]=hist_update(val,HIST,C,dC)
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19 |
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20 | valplus=[];valminus=[];
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21 | HISTplus=[];HISTminus=[];
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22 | if isempty(HIST)
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23 | HIST=0;
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24 | end
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25 | siz=size(C);nbfields=siz(2);
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26 | C=double(C);
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27 | valmin=min(val);
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28 | valmax=max(val);
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29 | Cmin=min(min(C)); Cmax=max(max(C));
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30 | if isempty(val)%no current histogram
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31 | val=[Cmin-dC/2:dC:Cmax+dC/2];
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32 | else %extending the current histogram beyond its maximum value
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33 | if Cmax>=valmax+dC/2;
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34 | valplus=[valmax+dC:dC:Cmax+dC/2];% we extend the values val
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35 | HISTplus=zeros(length(valplus),nbfields);% we put histogram to zero at these values
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36 | end
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37 | %extending the current histogram below its minimum value
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38 | if Cmin<=valmin-dC/2;
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39 | valminus=[valmin-dC:-dC:Cmin-dC/2];% we extend the values val
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40 | valminus=sort(valminus);% we reverse the order
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41 | HISTminus=zeros(length(valminus),nbfields);% we put histogram to zero at these values
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42 | end
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43 | val=[valminus val valplus];
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44 | end
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45 | HIST=[HISTminus;HIST;HISTplus];
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46 | if nbfields==1
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47 | histC=(hist(C,val))';% initiate the global histogram
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48 | elseif nbfields==3
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49 | HIST1=(hist(C(:,1),val))';
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50 | HIST2=(hist(C(:,2),val))';
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51 | HIST3=(hist(C(:,3),val))';
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52 | histC=[HIST1 HIST2 HIST3];
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53 | end
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54 | HIST=HIST+histC;
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