e
</dt><dd><p>
This example produces equivalent SIFT descriptors using
<a href="VL_DSIFT.html">VL_DSIFT</a>() and <a href="VL_SIFT.html">VL_SIFT</a>():
</p><pre>
 binSize = 8 ;
 magnif = 3 ;
 Is = vl_imsmooth(I, sqrt((binSize/magnif)^2 - .25)) ;

 [f, d] = vl_dsift(Is, 'size', binSize) ;
 f(3,:) = binSize/magnif ;
 f(4,:) = 0 ;
 [f_, d_] = vl_sift(I, 'frames', f) ;
</pre></dd><dt>
Remark
</dt><dd><p>
The equivalence is never exact due to (i) boundary effects
and (ii) the fact that <a href="