Mostrar imágenes carpeta upload

chdir('upload');

if ($gestor = opendir('.')) {
while (false !== ($entrada = readdir($gestor))) {
if ($entrada != "." && $entrada != "..") {
$info= pathinfo($entrada);
if ($info['extension']=="jpg" || $info['extension']=="png"){
 echo '<img width="50" height="50" src="upload/'.$entrada.'">';
}
}
}
closedir($gestor);
}