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klt, a tracking algorithm

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<h2> KLT_FeatureHistory </h2> 

<h2> 
<code>
typedef struct  {<br>
     int nFrames;<br>
     KLT_Feature *feature;<br>
}  *KLT_FeatureHistory;<br>
</code>
</h2>

A KLT_FeatureHistory is an array of features.  The <code>nFrames</code> field
indicates the number of features allocated, or rather the number of
frames in which the feature's data is given.
It must not be changed manually.<p>

NOTE: Although a feature list and a feature history look similar, the former
is intended to refer to an array of features from a single image, while
the latter refers to the same feature tracked through several images.<p>

The following code illustrates how to access the data 
in a feature history:

<pre width = 80>
KLT_FeatureHistory fh;
int frame;

for (frame = 0 ; frame < fh->nFrames ; frame++)  {
     printf("(%5.1f,%5.1f) = %d\n", 
          fh->feature[frame]->x,
          fh->feature[frame]->y,
          fh->feature[frame]->val);
}
</pre>


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