1. A pattern recognition system comprising: a) at least one capture device configured to acquire at least one sample, each of said at least one sample associated with a sample identifier; b) a basis configured to encode at least one of said at least one sample, said basis derived using a multitude of representative training samples; c) at least one quality checker configured to evaluate the quality of at least one of said at least one sample; d) at least one feature extractor configured to generate at least one signature from at least one of said at least one sample using said basis; e) a gallery, said gallery including at least one gallery sample, each of said at least one gallery sample being one of said at least one signature; f) a rejection threshold, said rejection threshold created using a rejection threshold learning mechanism, said rejection threshold learning mechanism configured to calculate said rejection threshold using at least one of said at least one sample by: i) swapping one of said sample identifier with other possible said sample identifier; ii) computing a credibility value (p) for each of the swapped sample identifiers; iii) deriving a peak-to-side ratio (PSR) distribution using a multitude of said credibility value; and iv) determining said rejection threshold using said peak-to-side ratio distribution; g) a storage mechanism configured to store at least one of said at least one gallery sample; and h) an open set recognition stage configured to authenticate or reject as unknown the identity of at least one unknown sample, by: i) deriving a set of credibility values by iteratively assign each of the gallery identifiers to the unknown sample and calculating a credibility value; ii) deriving a peak-to-side ratio for said unknown sample using said set of credibility values; iii) comparing said peak-to-side ratio for said unknown sample to said rejection threshold; iv) rejecting said unknown sample as unknown if said peak-to-side ratio is less than or equal to said rejection threshold; and v) finding the closest of said at least one gallery sample if said peak-to-side ratio is greater than said rejection threshold.