<a href="<?php echo $Enlace; ?>">Enlace</a>

<?php
urlink("Este es el link", "http://foro.elhacker.net", "");
?>

<img src="/display.php?id=34" border="0">With an ever changing ID of course. That's the part referencing my images in the database. The following is the code from the script which I use to retrieve the image from the database: 
<?

$connection=@mysql_connect(...);

@mysql_select_db(...);

$query="SELECT mime, file FROM images WHERE id=".$_GET["id"];

$rawdb=@mysql_query ($query,$connection);

if($rawdb AND @mysql_num_rows($rawdb)>0){

  $array=@ mysql_fetch_array($result);

  if (!empty($array["fileContents"])){

    // Output the MIME header

    header("Content-Type: ".$array["mime"]}");

    // Output the image

    echo $array["file"];

  }else{

    // something else...

  }

  @mysql_free_result($rawdb);

}else{

  // something else...

}

@mysql_close($connection);

?>Since I already have a session for each user that comes to my website, I just added the following: 
<img src="/display.php?id=34&sid=3839839039039393829" border="0">And implement a small session checkup in the script itself: 
<?

session_start();

if($_SESSION["is_known"]){

  // do database calls

}else{

  header("Location:http://mydomain.tld/dontstealmyimages.html");

}

?>