Barcode structural pre-compensation optimization

Abstract

Barcode print payload density is significantly improved when the effects of the print-scan (PS) cycle are anticipated in the barcode elements before printing. The PS cycle generally causes dot gain, and thus the black portions of the barcodes expand relative to the white portions. Structural pre-compensation (StructPC) anticipates this effect by removing black pixels from the boundaries of the black elements (modules and calibrating sections) of the barcodes. In this paper, we varied the amount of StructPC from 0 to 6 pixels for 2D DataMatrix barcodes that were printed at 600 dpi. Module sizes were varied from 10 to 30 mils (6 to 18 pixels at print resolution), using ECC 200 (∼30% error- correcting code). Test sets were printed on four types of printers. Each printer set underwent 2 additional PS cycles. We evaluated the optimal StructPC for each printer type after the combined 1, 2 and 3 PS cycles. We used the same substrate (office paper) throughout. Our findings support the implementation of StructPC for 2D barcodes. For every printer, the smallest readable barcode size was obtained with StructPC applied. StructPC results were printer-dependent: optimally 2 pixels for the dry electrophotographic printer, and optimally 2-5 pixels for thermal inkjet printers.