14. The system of claim 13 , wherein selecting the subset includes: selecting a feature with a highest contribution value when the highest contribution value meets a threshold; and selecting a quantity of features with highest contribution values when a combination of the contribution values meets the threshold.
14. The system of claim 13 , wherein selecting the subset includes: selecting a feature with a highest contribution value when the highest contribution value meets a threshold; and selecting a quantity of features with highest contribution values when a combination of the contribution values meets the threshold. 16. The system of claim 14 , wherein the contribution value for a particular feature is related to a statistical descriptor associated with the particular feature.