load 'paleta.pal'
#set a grey(#222222) background color
set object 1 rectangle from screen 0,0 to screen 1,1 fillcolor rgb"#222222" behind
set output "grey.png"
set border lw 3 lc rgb "white"
set xtics textcolor rgb "white"
set ytics textcolor rgb "white"
set key textcolor rgb "white"
plot "data.dat" using 1:2:(arg($3+$4*{0,1})) "(%lf,%lf) (%lf,%lf)" palette
pause -1