SOME ISSUES RELATED TO FIXED-RATE PRUNED TREE-STRUCTURED VECTOR QUANTIZERS

It is shown that the generalized BFOS algorithm is not optimal when it is used to design fixed-rate Pruned Tree-Structured Vector Quantizers (PTSVQ). A simple modification is made in the algorithm which makes it optimal. However, our experimental results show little difference between the rate-distortion curves generated with the original algorithm and the one proposed in this correspondence. An asymptotic analysis is presented which shows how the two algorithms prune the TSVQ and explains why their results are so similar. The analysis also shows that in designing fixed-rate variable-depth TSVQ's one can get as good a rate-distortion performance with a greedy TSVQ growing algorithm as with the optimal pruning of a large tree.