Has anyone implemented in Mathematica the Earth Mover's Distance (EMD)? A concept dating back to Monge 1871, used to compare histograms and images, e.g., the CIEDE2000 Color Difference algorithm. Yossi Rubner's C implementation can be found here:
Computation of EMD is more involved than Euclidean metric. EMD is a linear constrained optimization problem, and so can be handled presumably via Mathematica's Linear Programming functionality. Although there's typically additional normalization stage, e.g.. found here.