(0,0): plasma noise

(1,0): derived from (0,0)

(2,0): derived from (1,0)

(3,0): derived from (2,0)

(0,1): derived from (0,0) and (2,1)

(1,1): derived from (1,0)

(2,1): derived from (1,0)

(3,1): derived from (3,0)

All created using The GIMP.