Error-Correcting Code (ECC) and Module Size Considerations in 2D Aztec Barcode Readability

Error-Correcting Code (ECC) provides robust readability to both linear and two-dimensional (2D) barcodes, particularly for localized damage. Many ECC approaches, however, are based on assumptions about the types of damage or the communication channel used. As the applications for barcodes rapidly evolve with the increasing ubiquity of mobile cameras, an evaluation of the trade off between ECC and simply increasing the size of the bar code modules is required. This article compares the impact of simply changing the module size versus using error correction—which exhausts a percentage of the symbol area without adding payload data. For three typical nondestructive types of damage—the print-scan cycle, low quality printing, and blurring—investigated here, there is compelling support for increasing the size of the barcode modules and foregoing ECC. Freeing barcodes from the need for ECC provides an additional advantage: namely, the barcodes can be scrambled to be unreadable under the defined barcode specification without a change in size or appearance. This is in contrast to the use of ECC, for which only a small minority of rearrangements of the data in the barcode would be "decodable." Thus, without the use of ECC, it is much harder for a would-be counterfeiter or other dishonest party to determine the scrambling approach. Additionally, we can create 2D barcodes that are not "readable" using commercially available reading software, except where so desired. These results are discussed in light of destructive damage and for different applications of 2D bar codes.