my %angles;  #I get angles from a file
my ($key1, $key2, @colors);
my ($i, $j) = 0;
my $red_val= 0;
my $yellow_val = 90;
my $green_val = 180;
my $angle;
my $im = new GD::Image (150, 1500);
foreach $key1 (sort (keys %angles)) {
     foreach $key2 (sort (keys %{$angles{$key1}})) {
            $angle = ${$angles{$key1}}{$key2}
            if ($angle <= $yellow_val) {
                $colors[$i]->[$j] = $im->colorAllocate(255, 255*(($angle-$red_val)/($yellow_val-$red_val)), 0);
            } else {
                 $colors[$i]->[$j] = $im->colorAllocate(255*(($green_val - $angle)/($yellow_val - $red_val)), 255*(1-(1-($angle-$green_val)/($yellow_val-$green_val)))*.5, 0);
            }
            $j++;
       }
       $j = 0;
       $i++;
}