# False-color from p169-170 of Janert's book
set title "False Color"
f(x,y,n,m) = cos(n*x)*cos(m*y) + cos(m*x)*cos(n*y)
set pm3d              # Turn on pm3d mode
set view map          # Switch to birds-eye view...
set size square       # ... and scale x- and y-axes equally
unset surface         # No need for a surface in a false-color plot!
set isosamples 300    # But we want good resolution.
set palette model RGB defined ( 0 'black', 1 'white' )
splot [-6:6][-6:6] f(x,y,2,5)