gistfile1.PL

use strict;
use warnings;
use Imager;

my $img = Imager->new;
$img->read( file => shift );

do {
    my $transparent = Imager::Color->new( 0, 0, 0, 0 );
    my $img2 = $img->copy;
    $img2->circle(
        color  => $transparent,
        r      => 200,
        x      => 300,
        y      => 200,
        aa     => 0,
        filled => 100
    );
    $img->compose( src => $img2, combine => "diff" );
};

$img->write( jpegquality => '100%', file => shift );