METHOD AND APPARATUS FOR ENHANCING RESOLUTION OF REFLECTANCE SIGNALS PRODUCED FROM MACHINE-READABLE SYMBOLS

A method and apparatus scans or images a machine-readable symbol to produce several reflectance profiles therefrom. The profiles are averaged to produce an averaged profile. Weighted coefficients for each profile are then computed based on the averaged profile. Using the weighted coefficients, a weighted profile from each of the profiles is then produced. Low pass filtering is applied to the weighted profile to filter noisy or gray level signals therefrom. The resulting filtered profile is transformed using a non-linear technique to enhance high amplitude signals, but suppress low amplitude signals. The resulting transform signal is stretched over the range of reflectance values. The resulting stretched signal is then decoded using, for example, techniques for decoding profiles that fail to resolve narrow (1-wide) elements in the machine-readable symbol.