V-optimal histograms are an example of a more "exotic" histogram. V-optimality is a Partition Rule which states that the bucket boundaries are to be placed as to minimize the cumulative weighted variance of the buckets. Implementation of this rule is a complex problem and construction of these histograms is also a complex process.
Read more about V-optimal Histograms: Definition, Examples, Advantages of V-optimality Vs. Equi-Width or Equi-Depth, Disadvantages of V-optimality Vs. Equi-Width or Equi-Depth, Construction Issues, Variations of V-optimal Histograms