In experiments with QBIC colour histograms, which have extremely skew distributions, we were unable to achieve better than 0.10 filtering on average.

And this was after "tuning" partition boundaries to place approximately equal numbers of points in each partition.

Before tuning, filtering factor was 0.70.

Conclusion VA-file performance is very sensitive to data distribution.

VA-files will also perform poorly if T_D is large   (we compute D for every signature)