1. A server for identifying and transmitting to a mobile device additional information relating to a query image obtained by a user with a mobile device, the server comprising: a reference image database storing one or more reference feature descriptors associated with one or more reference images, wherein at least one reference image feature descriptor is mapped to a plurality of first addresses within an address space in the reference image database using a plurality of functions, and wherein the plurality of functions is configured to map one or more feature descriptors to the same address space; and a processor for executing one or more modules comprising: a query receiving module for receiving, from the mobile device, a first query including one or more query image feature descriptors; a candidate feature descriptors retrieval module for: calculating, for each of the one or more query image feature descriptors, a plurality of second addresses using the plurality of functions, and for each of the plurality of second addresses, determining a number of duplicate reference image feature descriptors stored within a pre-defined region of the reference image database; a candidate images retrieval module for: selecting a set of reference image feature descriptors based on the determined number of duplicate reference image feature descriptors; an image matching module for: comparing the selected set of reference image feature descriptors with the one or more query image feature descriptors to determine if any of the one or more reference images match the query image; wherein, if a matching reference image is determined, the server is further configured to perform the steps of: obtaining additional information associated with the at least one matching reference image from an annotation database, and transmitting the additional information to the mobile device for displaying as additional information relating to the at least one item of interest to the user.