asset() function in symfony3 does not convert url

i want to load pictures dynamicly from database ,

here's the table containing the image informations http://ift.tt/2o9HRRM

Controller code

public function listeproductAction()
{
    $em = $this->getDoctrine()->getManager();
    $img = $em->getRepository('AppBundle:image')->findAll();
    return $this->render('lucky/images.html.twig', array(
        'img' => $img ,

    ));

}

twig code

result

<div class="main-content">
        <img src="/uploads/brochures/0fa58c757752ced32d04b57bb7fa0d65.png ">
    </div>

the problem that asset funtion doesent find the image :(