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15<div><a href="../index.html">Home</a> &gt;  <a href="index.html">.</a> &gt; hist_update.m</div>
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19
20<h1>hist_update
21</h1>
22
23<h2><a name="_name"></a>PURPOSE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
24<div class="box"><strong>'hist_update': update of a current global histogram by inclusion of a new field</strong></div>
25
26<h2><a name="_synopsis"></a>SYNOPSIS <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
27<div class="box"><strong>function [val,HIST]=hist_update(val,HIST,C,dC) </strong></div>
28
29<h2><a name="_description"></a>DESCRIPTION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
30<div class="fragment"><pre class="comment">'hist_update': update of a current global histogram by inclusion of a new field
31------------------------------------------------------------------------
32[val,HIST]=hist_update(val,HIST,C,dC)
33
34 OUTPUT:
35 val: vector of field values at which the histogram is determined (middle of bins)
36 HIST(:,icolor): nbre of occurence of the field value in the bins whose middle is given by val
37           can be a column vector, same size as val, or a matrix with three columns, for color images
38
39 INPUT:
40 val: existing field values from the current histogram, =[] if there is no current histogram
41 HIST(:,icolor): current histogram,  =[] if there is none
42       can be a column vector (icolor=1), same size as val, or a matrix with three columns, for color images     
43 C(:,icolor): vector representing the current field values
44       can be a column vector (icolor=1), or a matrix with three columns, for color images
45 dC: width of the new bins extending val to account for the new field.</pre></div>
46
47<!-- crossreference -->
48<h2><a name="_cross"></a>CROSS-REFERENCE INFORMATION <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
49This function calls:
50<ul style="list-style-image:url(../matlabicon.gif)">
51</ul>
52This function is called by:
53<ul style="list-style-image:url(../matlabicon.gif)">
54</ul>
55<!-- crossreference -->
56
57
58<h2><a name="_source"></a>SOURCE CODE <a href="#_top"><img alt="^" border="0" src="../up.png"></a></h2>
59<div class="fragment"><pre>0001 <span class="comment">%'hist_update': update of a current global histogram by inclusion of a new field</span>
600002 <span class="comment">%------------------------------------------------------------------------</span>
610003 <span class="comment">%[val,HIST]=hist_update(val,HIST,C,dC)</span>
620004 <span class="comment">%</span>
630005 <span class="comment">% OUTPUT:</span>
640006 <span class="comment">% val: vector of field values at which the histogram is determined (middle of bins)</span>
650007 <span class="comment">% HIST(:,icolor): nbre of occurence of the field value in the bins whose middle is given by val</span>
660008 <span class="comment">%           can be a column vector, same size as val, or a matrix with three columns, for color images</span>
670009 <span class="comment">%</span>
680010 <span class="comment">% INPUT:</span>
690011 <span class="comment">% val: existing field values from the current histogram, =[] if there is no current histogram</span>
700012 <span class="comment">% HIST(:,icolor): current histogram,  =[] if there is none</span>
710013 <span class="comment">%       can be a column vector (icolor=1), same size as val, or a matrix with three columns, for color images</span>
720014 <span class="comment">% C(:,icolor): vector representing the current field values</span>
730015 <span class="comment">%       can be a column vector (icolor=1), or a matrix with three columns, for color images</span>
740016 <span class="comment">% dC: width of the new bins extending val to account for the new field.</span>
750017
760018 <a name="_sub0" href="#_subfunctions" class="code">function [val,HIST]=hist_update(val,HIST,C,dC)</a>
770019
780020 valplus=[];valminus=[];
790021 HISTplus=[];HISTminus=[];
800022 <span class="keyword">if</span> isempty(HIST)
810023     HIST=0;
820024 <span class="keyword">end</span>
830025 siz=size(C);nbfields=siz(2);
840026 C=double(C);
850027 valmin=min(val);
860028 valmax=max(val);
870029 Cmin=min(min(C)); Cmax=max(max(C));
880030 <span class="keyword">if</span> isempty(val)<span class="comment">%no current histogram</span>
890031     val=[Cmin-dC/2:dC:Cmax+dC/2];
900032 <span class="keyword">else</span> <span class="comment">%extending the current histogram beyond its maximum value</span>
910033     <span class="keyword">if</span> Cmax&gt;=valmax+dC/2;
920034         valplus=[valmax+dC:dC:Cmax+dC/2];<span class="comment">% we extend the values val</span>
930035         HISTplus=zeros(length(valplus),nbfields);<span class="comment">% we put histogram to zero at these values</span>
940036     <span class="keyword">end</span>
950037     <span class="comment">%extending the current histogram below its minimum value</span>
960038     <span class="keyword">if</span> Cmin&lt;=valmin-dC/2;
970039         valminus=[valmin-dC:-dC:Cmin-dC/2];<span class="comment">% we extend the values val</span>
980040         valminus=sort(valminus);<span class="comment">% we reverse the order</span>
990041         HISTminus=zeros(length(valminus),nbfields);<span class="comment">% we put histogram to zero at these values</span>
1000042     <span class="keyword">end</span>
1010043     val=[valminus val valplus];
1020044 <span class="keyword">end</span>
1030045 HIST=[HISTminus;HIST;HISTplus];
1040046 <span class="keyword">if</span> nbfields==1
1050047     histC=(hist(C,val))';<span class="comment">% initiate the global histogram</span>
1060048 <span class="keyword">elseif</span> nbfields==3
1070049     HIST1=(hist(C(:,1),val))';
1080050     HIST2=(hist(C(:,2),val))';
1090051     HIST3=(hist(C(:,3),val))';
1100052     histC=[HIST1 HIST2 HIST3];
1110053 <span class="keyword">end</span>
1120054 HIST=HIST+histC;</pre></div>
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