A fast retrieval algorithm for the earth mover´s distance using EMD lower bounds and the priority queue

Earth mover´s distance (EMD) is a distance measure between two distributions, and has been widely used in multimedia information retrieval systems, especially content-based image retrieval systems. When the EMD is applied to image problems based on color or texture, the EMD reflects the human perceptual similarities. Its computations, however, is too expensive to use in large-scale databases. In order to achieve the efficient computation of the EMD during query processing, we have developed ldquofastEMDrdquo, a library for high-speed feature-based similarity retrievals in large databases. This paper introduces techniques that are used in the implementation of the fastEMD and demonstrates the efficiency in extensive experiments.