3 Overview
Figure 3 provides a workflow of our halftone QR code synthesis.
First, we generate a QR code using a data encoding library [Kentaro
2006] that adheres to ISO standard [ISO/IEC 18004 2006]. The
setting used to generate a QR code consists of three parameters:
data string, symbol version, and error correction level. While the
data string represents the encoded information that determines the
appearance of QR code, symbol version and error correction level
control the size and error correction capacity of QR code, respectively.
The QR code modules are black or white squares, and can be
classified into two categories according to their functionality. The
first category contains data modules, which are modules that represent
input data or error correction codes; while, the second category
are modules that are used to improve the reading performance
(e.g., for alignment, rectification, etc.). Because the readability of
QR code is very sensitive to the correctness of modules in the second
category, our algorithm leaves these modules untouched and
only manipulates the data modules.We recommend readers to refer
to the QR code ISO standard [ISO/IEC 18004 2006] and the official
web site [DENSO WAVE 2003] for technical details regarding QR
code generation.