QArt Codes: Applied Reed-Solomon coding

This is a continuation of the previous article "Finite Field Arithmetic and Reed-Solomon Coding"[1]

[1]: http://research.swtch.com/field

Regarding the portrait used in many of the example QR codes:

  For some reason, the portrait of Peter Weinberger has always been 
  our most popular target for picture editing experiments. [1]

[1]: http://swtch.com/pjw