minor fix at SIFT local feature computation (redundancy removed)

features/localfeatures/LocalFeatureSift.cpp

@@ -159,8 +159,8 @@ void LocalFeatureSift::withPP( const NICE::Image & img, VVector & positions, VVe
 
     VL::Sift sift( blockimgfl, img.width(), img.height(),
                    sigman, sigma0, O, S, omin, -1, S+1) ;
-
-    sift.process ( blockimgfl, img.width(), img.height() );
+    //calling sift.process(.) already done in VL::Sift constructor, so omit the following process function
+    //sift.process ( blockimgfl, img.width(), img.height() );
 
     sift.setMagnification ( magnif );
     sift.setNormalizeDescriptor ( normalizeFeature );