METHOD OF SCANNING INDICIA USING SELECTIVE SAMPLING

A method of reading an indicia, for example a bar code, comprising areas of differing light reflectivity comprises producing an electrical signal representative of light reflected from the indicia and selectively sampling the signal at a rate well below the Nyquist rate. The sample points are not uniform, and are chosen to represent key features in the signal. An attempt is then made to decode the indicia, using the samples. If the decode is unsuccessful, the samples which have been collected are analyzed to provide information on the extent to which they represent true data corresponding to the indicia, and the extent to which they present noise. Signal collection and/or processing and/or sampling is then adjusted and the process is repeated. The continual feed-back of information related to the scanning environment allows more aggressive decoding techniques to be used.