From Adam Majewski@21:1/5 to All on Sun Jan 5 13:27:11 2020
I can also check:
gnuplot> show palette
palette is GRAY
figure is POSITIVE
all color formulae ARE NOT written into output postscript file
allocating ALL remaining color positions for discrete palette terminals
Color-Model: RGB
gamma is 1.5
gnuplot> show palette gradient
color mapping *not* done by defined gradient.