System for encoding and decoding data in machine readable graphic form

摘要

A system for representing and recognizing data in machine readable graphic image form in which data to be encoded is entered into the system and a processor encodes the data into a two-dimensional bar code symbol and generates transfer drive signals representative of the symbol. A transferring device such as a printer transfers an image of the two-dimensional bar code symbol onto a carrier such as a card or paper document in response to the transfer drive signals. A recognition device converts the image on the carrier into electrical signals representative of the symbol by scanning the image. A low-level decoder decodes the signals by decoding each scan line into a vector of codeword values corresponding to the codewords in the two-dimensional bar code symbol, assigning a row number to each of the codeword yalues, and then filling in a two-dimensional matrix with the codeword values. A high-level decoder further decodes the codeword values into data which can then be output for processing or use. <IMAGE>