ENHANCED MATRIX SYMBOL ERROR CORRECTION METHOD

A system and method for error correction for machine-readable symbols having data codewords, and having error correction (EC) codewords derived from the data codewords and redundantly indicating the location and data contents of the data codewords. The symbols use Reed-Solomon (RS) error correction to retrieve damaged codewords. RS error correction normally requires two EC codewords to identify both the location and data contents of a data codeword. The present system and method perform optical contrast analysis on the codewords, identifying those codewords with the lowest contrast levels (that is, the least difference between the reflectance of the black or white cells and the black/white threshold). Codewords with the lowest contrast levels are flagged as optically ambiguous, thereby marking, in the EC equations, the locations of the codewords most like to be in error. As a result, only a single EC codeword is required to retrieve the data for a flagged data codeword.