Abstract
We present optimized modulation and coding for the recently introduced
dual modulated QR (DMQR) codes that extend traditional QR codes to carry
additional secondary data in the orientation of elliptical dots that
replace black modules in the barcode images. By dynamically adjusting
the dot size, we realize gains in embedding strength for both the
intensity modulation and the orientation modulation that carry the
primary and secondary data, respectively. Furthermore, we develop a
model for the coding channel for the secondary data that enables
soft-decoding via 5G NR (new radio) codes already supported by mobile
devices. The performance gains for the proposed optimized designs are
characterized via theoretical analysis, simulations, and actual
experiments using smartphone devices. The theoretical analysis and
simulations inform our design choices for the modulation and coding, and
the experiments characterize the overall improvement in performance for
the optimized design over the prior unoptimized designs. Importantly,
the optimized designs significantly increase usability of DMQR codes
with commonly used QR code beautification that cannibalizes a portion of
the barcode image area for the insertion of a logo or image. In
experiments with a capture distance of 15 inches, the optimized designs
increase the decoding success rates between 10% and 32% for the
secondary data while also providing gains for primary data decoding at
larger capture distances. When used with beautification in typical
settings, the secondary message is decoded with a high success rate for
the proposed optimized designs, whereas it invariably fails for the
prior unoptimized designs.