Hi here is way of resize image after loading...
ActionScript Code:
import flash.display.Loader;
import flash.net.URLLoader;
import flash.events.*;
var _loader:Loader=new Loader();
_loader.contentLoaderInfo.addEventListener(Event.COMPLETE,onLoadingComplete);
_loader.load(new URLRequest("http://www.thesquashracket.com/wallpapers/nature/165858ducks.jpg"));
addChild(_loader);
function onLoadingComplete(evt:Event) {
trace(["before resize",evt.target.content.height,evt.target.content.width]);
evt.target.content.height=100;
evt.target.content.width=100;
trace(["After resize",evt.target.content.height,evt.target.content.width]);
}