Код AS3:
container = new Sprite();
addChild(container);
var pic:Loader = new Loader();
pic.load(new URLRequest("1.jpg"));
pic.contentLoaderInfo.addEventListener(Event.COMPLETE, onLoadImageComplete);
conteiner.addChild(pic);
private function onLoadImageComplete(event:Event):void {
//позиционирование -width / 2, -height / 2
}