1. A method to be executed on a computing device, the method comprising: generating a matrix of a distribution of features of one or more images; determining correlations between the features of the one or more images as a function of the generated matrix; grouping the features into one or more groups based at least in part on the correlations such that between-group correlations are minimized and within-group correlations are maximized; constructing a sub-metric for each of the one or more groups; and combining all of the sub-metrics into a global metric.