Coloured QR codes for the Internet of Things

The access and exchange of information increased dramatically in the last years and Quick Response (QR) codes are a facilitating technology. Assembled with black and white modules and able to store different types of information (numeric, alphanumeric, kanji, kana) with high density and robustness to reading errors, QR codes have spark interest and visibility among users being applied in several fields of society. Challenges encompass the increase of storage capacity to keep promoting their use in a broader range of applications. We propose the use of multiplexing methods based on colour to generate high density QR codes with 3 times storage capacity increased when compared to traditional QR codes. A methodology to decode the multiplex coloured QR code, based on colour separation threshold aided by maximum likehood criteria to minimize the error associated with decoding and maximizing the foreseen storage capacity, is also presented.