comparison Code/Descriptors/Matlab/Common/findMaxima.m @ 4:92ca03a8fa99 tip

Update to ICASSP 2013 benchmark

+function [Maxima, countMaxima] = findMaxima(f, step)
+
+%
+% MAXIMA ESTIMATION
+%
+% function [Maxima, countMaxima] = findMaxima(f, step);
+%
+% This function estimates the local maxima of a sequence
+%
+% ARGUMENTS:
+% f: the input sequence
+% step: the size of the "search" window
+%
+% RETURN:
+% Maxima: [2xcountMaxima] matrix containing: 
+%         1. the maxima's indeces
+%         2. tha maxima's values
+% countMaxima: the number of maxima
+%
+
+
+
+%
+% STEP 1: find maxima:
+% 
+
+countMaxima = 0;
+for (i=1:length(f)-step-1) % for each element of the sequence:
+    if (i>step)
+        if (( mean(f(i-step:i-1))< f(i)) && ( mean(f(i+1:i+step))< f(i)))  
+            % IF the current element is larger than its neighbors (2*step window)
+            % --> keep maximum:
+            countMaxima = countMaxima + 1;
+            Maxima(1,countMaxima) = i;
+            Maxima(2,countMaxima) = f(i);
+        end
+    else
+        if (( mean(f(1:i))<= f(i)) && ( mean(f(i+1:i+step))< f(i)))  
+            % IF the current element is larger than its neighbors (2*step window)
+            % --> keep maximum:
+            countMaxima = countMaxima + 1;
+            Maxima(1,countMaxima) = i;
+            Maxima(2,countMaxima) = f(i);
+        end
+        
+    end
+end
+
+%
+% STEP 2: post process maxima:
+%
+
+MaximaNew = [];
+countNewMaxima = 0;
+i = 0;
+while (i<countMaxima)
+    % get current maximum:
+    i = i + 1;
+    curMaxima = Maxima(1,i);
+    curMavVal = Maxima(2,i);
+    
+    tempMax = Maxima(1,i);
+    tempVals = Maxima(2,i);
+    
+    % search for "neighbourh maxima":
+    while ((i<countMaxima) && ( Maxima(1,i+1) - tempMax(end) < step / 2))
+        i = i + 1;
+        tempMax(end+1) = Maxima(1,i);
+        tempVals(end+1) = Maxima(2,i);
+    end
+    
+   
+    % find the maximum value and index from the tempVals array:
+    %MI = findCentroid(tempMax, tempVals); MM = tempVals(MI);
+    
+    [MM, MI] = max(tempVals);
+        
+    if (MM>0.02*mean(f)) % if the current maximum is "large" enough:
+        countNewMaxima = countNewMaxima + 1;   % add maxima
+        % keep the maximum of all maxima in the region:
+        MaximaNew(1,countNewMaxima) = tempMax(MI); 
+        MaximaNew(2,countNewMaxima) = f(MaximaNew(1,countNewMaxima));
+    end        
+    tempMax = [];
+    tempVals = [];
+end
+
+Maxima = MaximaNew;
+countMaxima = countNewMaxima;
+
+