System for encoding and decoding data in machine readable graphic form

A method for decoding a two-dimensional bar code symbol, the bar code symbol including a plurality of ordered, adjacent rows of codewords of bar-coded information from a set of codewords, the set of codewords being partitioned into at least three mutually exclusive clusters, each row in the symbol having at least one row indicator codeword and containing only codewords from a cluster different from the codewords in an adjacent row, comprising the steps of:

• scanning the two-dimensional bar code symbol to produce scan lines of data representing the bar-coded information in the codewords of the symbol;
• decoding a scan line of data into a vector of codeword values corresponding to the codewords that were scanned, at least one of the codeword values being for a row indicator codeword;
• assigning a row number to each of the codeword values in the vector based on the value of the row indicator codeword and the cluster of the codeword;
• and
• filling in a codeword matrix with the codeword values in the vector according to their assigned row numbers.

A system for representing and recognizing data on a record carrier in the form of a machine readable two-dimensional bar code structure comprising:

• encoding means including:
• means for entering data in said encoding means,
• processing means for encoding said data into a two-dimensional bar code structure and for generating transfer drive signals, the bar code structure including a plurality of ordered, adjacent rows of codewords of bar-coded information from a set of codewords, the set of codewords being partitioned into at least three mutually exclusive clusters, each row in the two-dimensional bar code structure having at least one row indicator codeword and containing only codewords from a cluster different from the codewords in an adjacent row,
• means for transferring an image of the two-dimensional bar code structure onto a portable record carrier in response to said transfer drive signals;
• and
• recognition means including:
• means for scanning the image of the two-dimensional bar code structure to produce scan lines of data representing the bar-coded information in the codewords of the two-dimensional bar code structure,
• means for decoding a scan line of data into a vector of codeword values corresponding to the codewords that were scanned, at least one of the codeword values being for a row indicator codeword,
• means for assigning a row number to each of the codeword values in the vector based on the values of the row indicator codeword and the cluster of the codeword, and
• means for filling in a codeword matrix with the codeword values in the vector according to their assigned row numbers.

A method for representing and recognizing data on a record carrier in the form of a machine readable two-dimensional bar code structure comprising the steps of:

• entering said data into an encoding station;
• encoding said data into a two-dimensional bar code structure, the two-dimensional bar code structure including a plurality of ordered, adjacent rows of codewords of bar-coded information from a set of codewords, the set of codewords being partitioned into at least three mutually exclusive clusters, each row in the two-dimensional bar code structure having at least one row indicator codeword and containing only codewords from a cluster different from the codewords in an adjacent row,
• transferring an image of the two-dimensional bar code structure onto a portable record carrier;
• scanning the image of the two-dimensional bar code structure to produce scan lines of data representing the bar-coded information in the codewords;
• decoding a scan line of data into a vector of codeword values corresponding to the codewords that were scanned, at least one of the codeword values being for a row indicator codeword;
• assigning a row number to each of the codeword values in the vector based on the value of the row indicator codeword and the cluster of the codeword;
• and
• filling in a codeword matrix with the codeword values in the vector according to their assigned row numbers.