Retrieve images from MySQL (stored as medimu BLOBs)

Hi out there,

How can I retrieve an image stored as a medium BLOB? First I just got som ugly chars. Then I wrote:

<?php
header("Content-type: image/gif");
?>

And yes I am sure that the images ext. is GIF.

Afterwards I got the following error displayd on ny screen:

Picture ".... URL ...." cannot be displayed, it contains errors.

/Daniel