fijate si asi te sirve
<?PHP
$Link_ID = odbc_connect("prueba", "", "");
$Query_ID = odbc_exec($Link_ID, "SELECT foto FROM investigadores WHERE ID=90");
$row=odbc_fetch_array($Query_ID);
header("content-type: image/jpeg");
echo "<img src=".$row['foto'].">";
echo $row['foto'];
echo $row;
?>