Memory usage. The memory usage of the three programs at different coverage levels (Chromosome 21 data). Note that Jellyfish and the naive counter are storing all k-mers while BFCounter filters out most unique k-mers without storing them explicitly in memory. The memory usage of BFCounter and the naive version roughly mimic the shape for the number of filtered k-mers in Figure 3. The discrete jumps in the memory usage of Jellyfish are due to implementation details as the size of the hash table has to be a power of 2.