\sigma(\bar{a}) & \sigma(\bar{b}) & \sigma(\bar{a}) \\
\sigma(\bar{a}) & \sigma(\bar{b}) & \sigma(\bar{a}) & \sigma(\bar{b}) \\
\sigma(d) & \sigma(c) & \sigma(d) & \sigma(c) \\
\sigma(a) & \sigma(b) & \sigma(a) & \sigma(b)
\end{pmatrix}.$$ The whole discrete description of the continuous pattern $B(x,y)$ follows after four iterations as $$\sigma(G) =
\left(\begin{array}{lllllllllllllllllllllllllllllllllll}
  w & b & w & b & w & b & w & w & r & w & r & w & r & w & r & w \cdots \\
  b & w & b & w & b & w & b & w & w & r & w & r & w & r & w & w \cdots \\
  w & b & w & b & w & b & w & w & r & w & r & w & r & w & r & w \cdots \\
  w & w & w & w & w & w & w & w & w & w & w & w & w & w & w & w \cdots \\
  r & w & r & w & r & w & r & w & w & b & w 