Assist channel coding with vertical block error correction

摘要

A system encodes a separate assist channel that carries only a small amount of additional information in a hardcopy document to compensate for failure of an OCR system to accurately reconstruct a scanned electronic version of the hardcopy document. The assist channel protects symbols printed on the hardcopy document by computing Reed-Solomon error correcting codes for vertical columns of symbols. Decoding is synchronized along a line of text at each symbol block. When an error correcting code corrects an error produced during OCR processing, the remainder of the line containing the error is revised.