Improved color barcodes via Expectation Maximization style interference cancellation

Abstract

Encoding data independently in cyan, magenta, and yellow (CMY) print colorant channels with detection in complementary Red, green, and blue (RGB) image capture channels offers an attractive framework for extending monochrome barcodes to color with increased data rates. The undesired absorption of colorants in regions of spectral sensitivity of the noncomplementary capture channels, however, gives rise to cross-channel color interference that significantly deteriorates the performance of the color barcode system. In this paper, we propose an Expectation Maximization (EM) style algorithm to estimate and cancel this color interference and improve the overall performance of the barcode system. Our method utilizes a physical model for print-capture process where the model parameters vary depending on printer, capture device, and illumination. We estimate the model parameters using an iterative EM-style approach and obtain an estimate of CMY colorant channels from the scanned RGB barcode by using the estimated model parameters. Our experimental results show that the proposed method mitigates the effect of color interference and significantly reduces the bit error rates for the recovered data.

Per-Colorant-Channel Color Barcodes for Mobile Applications: An Interference Cancellation Framework

“…The versatility of the framework proposed in this paper is further illustrated by the fact that the methodology can also be applied to high capacity color barcodes recently proposed in [10], an application that we report in related recent work [2]. The high capacity barcodes in [10] are intended for document workflow rather than mobile applications, where the data is to be recovered from a scanner rather than a digital camera capture of the barcode.…”

Improvement in two-dimensional barcode

“…As the intensity of the colour varies, the colour barcode becomes more complex thus increasing the complexity of decoding algorithm. As three single colour barcodes are combined to form a single multi-colour barcode, interference between the colours of single-colour barcode takes place as shown in figure 1 [7].…”

“…However, the use of colours for encoding poses challenges in the presence of inevitable tonal variations in the print and capture processes which cause changes in the colours and to make decoding feasible. A separate algorithm needs to be implemented in order to decode the barcode, due to the interference among the colours [7]. Due to the interference, the decoding algorithm becomes more complex [4][5][6].…”

Designing a 2D color barcode

“…Bulan and Sharma [6] proposed an Expectation Maximization (EM) algorithm attempted to improve the color barcode during color interference. They were able to cancel the color interferences and also improved bit error rate performance of the secondary colors such as cyan, magenta and yellow.…”

“…They used eight colors to form color tiles in the color barcode. In order to maximize the security function of the color barcode two algorithms were performed for the authentication of the color barcode: The RGB Distance Approach and Hue approach [6]. The Hue distance approach gave better results.…”