void Start(){
Screen.orientation = ScreenOrientation.Portrait;
// Get the aspect ratio of the current screen
float screenProp = (float)Screen.width / (float)Screen.height;
// Change the size of the background image
SpriteRenderer backgroundImg = GetComponent<SpriteRenderer> ();
float newSize = (16f/9f) *screenProp;
backgroundImg.transform.localScale = new Vector3 (newSize, 1, 1);
}