1. An improved method for discriminating between currency bills of different denominations comprising the acts of: illuminating a predetermined section of a currency bill by focusing at least one strip of light thereupon; detecting the light reflected off said illuminated section of said bill to generate an analog reflectance signal; generating relative lateral displacement between said strip of light and said bill so as to illuminate and optically scan successive sections of said bill along a predetermined dimension thereof; obtaining a series of analog reflectance signals corresponding to light reflected from each of said successive bill sections; digitizing and processing said series of analog reflectance signals to yield a set of digital data samples which, in combination, represent a data pattern characteristic of the currency denomination of said bill; generating and storing a set of master characteristic patterns corresponding to optical scanning of original bills of each of the different currency denominations to be discriminated; dividing at least one of (1) said data pattern and (2) said master characteristic patterns into a plurality of sections, and shifting selected ones of said sections relative to each other; and comparing said data pattern for said scanned currency bill to each of said stored master patterns to determine the degree of correlation therebetween, and thereby to identify the denomination of said currency bill.