Here's some example code:

use strict;
use warnings;
use Image::Magick;

my $image = Image::Magick->new(
    size  => '1024x100',
    type  => 'Greyscale',
    depth => 16,
);
$image->Read('xc:white');

for ( 0 .. 1023 ) {
    my $color = sprintf "gray(%2.3f%%)", 100 * $_ / 1023;
    my $res = $image->Draw(
        primitive => 'line',
        stroke    => $color,
        points    => "$_,0 $_,100",
    );
    warn $res if $res;
}
for ( 0 .. 16 ) {
    $image->SetPixel(
        x     => int( (16 - $_) * 1023 / 16 ),
        y     => 50,
        color => [ ( $_ / 16 ) x 3 ],
    );
}

my $res = $image->Write( filename => "grey.png" );
warn $res if $res;
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Why are you ignoring Markup in the Monastery? Also there's bold warning below post text area: Put <p> </p> tags around your paragraphs. Put <code> </code> tags around your code and data!

Update: added SetPixel demo