set term png enhanced transparent
set xlabel 'x' offset 2
set ylabel 'y' offset -2
set pm3d explicit at st      # draw on bottom, not as 3d surface
set pm3d corners2color c4
set pm3d map
set palette negative gray
set output 'DalitzXY.png'
splot 'DalitzXY.dat' u 1:2:3  w pm3d notitle