Pas d'afichage de ma requête

<?php
if(isset($_POST['img']) AND !empty($_POST['img'])){
    $img = isset($_POST['img']) ? $_POST['img']: NULL;
    $img = !empty($_POST['img']) ? $_POST['img']: NULL;
    $req = $pdo->query("SELECT * FROM galeries INNER JOIN users ON galeries.user_id=users.id");
    $req->setFetchMode(PDO:: FETCH_ASSOC);
    $req->execute();
    if($req->rowCount()>0){
            while($picture = $req->fetchAll()){
                    ?>
                    <img src="<?= $picture->img ?>"width="430" height="225"/>
                    <?php
            }
    }
}
?>