Thumb auto resize

How can I autosize images in actionscript 3?

First the loader creation:
[COLOR=Blue]
l = new Loader();
thumb.here.addChild(l);
var urlRequeste:URLRequest = new URLRequest(main_fotos*.imagem);
l.load(urlRequeste);
l.contentLoaderInfo.addEventListener(Event.COMPLETE, completeHandler);[/COLOR]

So when load is complete, the function is called:

[COLOR=Blue]function completeHandler(evt:Event):void {
trace(evt.currentTarget.width)
}
[COLOR=Black]
The trace outputs the width correct. But it is read olny. How can I resize it?[/COLOR]
[/COLOR]