dynmap/web/gettiles.php

<?php

define('TILESPATH', 'tiles/');

$path = $_SERVER['PATH_INFO'];

$fname = TILESPATH . $path;

if (!file_exists($fname)) {
    $fname = "images/blank.png";
}
$fp = fopen($fname, 'rb');
if (strstr($path, ".png")) {
    header("Content-Type: image/png");
} else {
    header("Content-Type: image/jpeg");
}

header("Content-Length: " . filesize($fname));

fpassthru($fp);
exit;