Patent ID: 6102292
Filing Date: 2000-08-15
Classification: G06K

Abstract:
A method of compensating the edge positions of a signal generated by scanning a bar code, wherein said signal (S(t), Sd(t)) has a substantially alternating waveform defined by a sequence of high-amplitude peaks separated by low-amplitude valleys; each peak corresponding to a space of the code (8) and each valley corresponding to a bar of the code (8); the peaks being joined to the valleys by steeply sloping waveform edges (F); characterized by comprising the steps of:calculating (160) a number of parameters (x), each representing a determined position (160) of a respective edge (F) along said waveform;determining (110) a global threshold (Vmed) calculated over substantially the whole of said signal;calculating (140) a local threshold (th) in a predetermined region of said signal;calculating (150) a local correction function (g) by means of said global threshold (Vmed) and said local threshold (th); andapplying (170) said local correction function (g) to a said calculated parameter (x) to generate an output corrected parameter (x') relative to a compensated position of said edge (F), said compensated position recovering possible shifts in the edge.