Halftone QR Code Generator by Lachlan Arthur
from http://jsfiddle.net/lachlan/r8qWV/
More about halftone QRCode:
http://vecg.cs.ucl.ac.uk/Projects/SmartGeometry/halftone_QR/halftoneQR_sigga13.html http://www.jianshu.com/p/46a4e210a542 http://spacekid.me/halftone-qr-code-generator/ https://zhuanlan.zhihu.com/p/20728355