my $xml = qx/mudraw -ttt $file/;
my $tree = XMLin($xml, ForceArray => [qw/page block line span char/]);

#going through the structure
for my $page (@{$tree->{page}}) {
    for my $block (@{$page->{block}}) {
        for my $line (@{$block->{line}}) {
            for my $span (@{$line->{span}}) {
                my $string = join '', map {$_->{c}} @{$span->{char}};
                #... do my stuff
            }
        }
    }
    $page_index ++
}