Postgres Large Object

Hi,
I' m a newbie with BLOBS.
I have pg-database with images in large object.
I read (with php) the blob but how to see this image ?

.......
pg_exec ($conn, "begin");
$handle=pg_loopen($conn,68129,"r");
$img=pg_loreadall($handle);
pg_loclose($handle);
pg_exec ($conn, "end");

echo "<img src=\"$img\" border=0>";

So i see only the blob like a sequence of chars

Thanks,
Enrico