I want to insert image into database but it show me undefined index

/////////////////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\
var_dump Information Bellow::

array
  'img' => string 'my passport.jpg' (length=15)

//////////////////\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\

 16  $_FILES['img']['tmp_name'];
 17  move_uploaded_file($_FILES['img']['tmp_name'],"upload/".$_FILES['img']['name']);
 18  $img = $_FILES['img']['tmp_name'];
 19  
 20  $con = new PDO("mysql:host=localhost; dbname=crime;","root","");
 21  $con->setAttribute(PDO::ATTR_ERRMODE, PDO::ERRMODE_WARNING);
 22  $sql = "insert into imagetbl (img) 
 23  values(:img)";
 24  $stmt = $con->prepare($sql);
 25  $stmt->bindParam('img',$img);