Patent ID: 7674995

Claim:
A method of processing postal items, which method comprises the following steps during a first pass for sorting the items: taking a digital picture of a postal item, deriving from said picture a digital fingerprint which is a logic identifier for the item, and storing the fingerprint of the item in a memory in correspondence with data about the item, and the method comprises the following steps during a second pass for sorting the items: taking again a digital picture of a current mail item, deriving from said image a digital fingerprint for the current item, searching the fingerprints recorded in the first sorting pass for a match with the fingerprint of the current item in order to retrieve the data about the item by association, sorting a current item by directing it toward a sorting outlet provided with sorting outlet bins if said match is obtained, and rejecting the current item by sending it to a reject outlet if no match is found, wherein said method further comprises during the first sorting pass: associating in the memory the fingerprints of the successive items with corresponding chronological serial numbers, chronological order being the order in which the items are loaded into the sorting outlet bins and during the second sorting pass, the method further comprises: recording data relative to matching obtained between fingerprints from second sorting pass fingerprints recorded in the memory in the first sorting pass, retrieving, for a series of successive item fingerprints which number equal to a certain threshold and for which matches have been obtained with fingerprints recorded in the memory in the first sorting pass, a series of chronological serial numbers associated with said matching fingerprints recorded in the memory in the first sorting pass, computing an estimated chronological serial number for a current item by means of a linear approximation from said series of chronological serial numbers, and searching for a match with the fingerprint of the current item on the basis of the estimated chronological serial number to limit exploration space for matching fingerprints, and during the second sorting pass, if no series of successive item fingerprints matching with fingerprints recorded in the memory in the first sorting pass can be obtained for a number of successive item fingerprints equal to said certain threshold, the method comprises: scanning, in full, fingerprints recorded in the first sorting pass until a match is found with the fingerprint of the current item is obtained.