cmd sample ($$;) { # saturation value
        draw axes none;
        $dd = 0.01;
        for ($d = 0; $d <= 1; $d += $dd) {
                set color hsv $d $_[0] $_[1];
                draw box filled ($d-$dd1) $_ybottom ($d+$dd) $_ytop;
        }
        set color black;
        draw axes;
        draw label "Saturation=$_[0] Value=$_[1]"
                at ($_xmargin + $_xsize + 1) ($_ymargin + $_ysize/2) cm;
        set y margin $_ymargin + $_ysize + 0.75;
        set x name "";
        set x format "";
        set y format "";
}
set x margin 2;
set y margin 4;
set x name "Hue";
set y name "";
set y size 1;
set y axis 0 1;
set x axis 0 1 0.5 0.1;
draw label "`pwd`/$_command_file" at $_xmargin ($_ymargin - 2) cm;

sample 1 1;
sample 0.8 1;
sample 0.6 1;
sample 0.4 1;
sample 0.2 1;
sample 0.0 1;
sample 1 0.8;
sample 1 0.6;
sample 1 0.4;
sample 1 0.2;
sample 1 0.0;