Patent ID: 7204422
Filing Date: 2007-04-17
Classification: G06K

Abstract:
1. A system for processing a signal imperfectly indicating perceived regions of relatively light and dark areas arranged in an alternating pattern as part of a binary optical code, the system comprising: a differentiator that generates a first derivative of the signal; a first comparator, connected to the differentiator, that compares the first derivative to a first threshold, the first comparator producing an output when the first derivative exceeds the first threshold; a second comparator, connected to the differentiator, that compares the first derivative to a second threshold, the second comparator producing an output when the first derivative is less than the second threshold; and a circuit receiving as an input the first derivative, the first derivative having a magnitude measured with respect to a reference level, the first derivative undergoing half-cycles of alternating polarity between successive crossings of the reference level, the first derivative having within a half-cycle a series of one or more successive local peaks of the same polarity as the half-cycle in which they occur, the circuit comprising: