Patent US 4,160,901

A coincidence testing method for enhancing the reliability of output data from a label reader adapted to read a bar code consisting of a plurality of bars. Each bar in the bar code is scanned at a plurality of points and sets of binary symbols representative of the scanned points along each bar are obtained. Then the binary symbols in each set are ordered to correspond to the order of the scanned points or segments along each bar. Then coincidence tests are performed on successive pairs of binary symbols in each set to determine whether a reliable decision can be made for each bar.