#set palette gray
set xrange [-1:37]
set yrange [-1:22]
set palette positive nops_allcF maxcolors 0 gamma 1.5 color model RGB
set palette defined ( 0 1 1 1, 0.1 0 0 1, 0.3 0 0.85 0.9,\
     0.6 0 0.75 0, 0.8 1 1 0, 1.0 1 0 0 )

set pm3d corners2color c2
set view map
splot [-1:36] [-1:25] "pre_wm" matrix title "# of chips with codes 0,39,96,97,98,99 in preproduction wafers, 14324 chips" with pm3d
pause -1
set terminal png
set output "pre_map.png"
replot
set output