1. A method for encoding a biometric data item, comprising: defining a biometric dataspace comprising a plurality of representatives of biometric data items stored in a database, wherein each representative is defined in accordance with a set of characteristics of a biometric data item; obtaining an acquired biometric data item; transforming said acquired biometric data item according to said set of characteristics to generate a transformed biometric data item; positioning the acquired biometric data item relative to the biometric dataspace by applying a comparison between the transformed biometric data item and each representative in the database to obtain N deviation values which position the acquired biometric data item relative to the biometric dataspace; and generating an encoded form of the acquired biometric data item as a representative vector for the acquired biometric data item, said representative vector having at most N components, wherein each one of said N components is determined as a function of a corresponding one of said N deviation values; wherein the representative vector for the biometric data item is a binary vector, and wherein each of the components is a binary value resulting from comparison against at least one threshold value; and wherein the binary vector is obtained by the following steps: determining a statistical noise value relative to each representative; obtaining a weight associated with each representative as a function of the statistical value relative to it; determining the binary components of the representative vector by comparing the deviation values obtained for the respective representatives to the threshold value, taking into consideration the associated weight obtained using a histogram of the distribution of the distances relative to each representative.