copyPixels and Alpha channel

programming flash
1

Hi,

I am having problems dealing with the alpha channel of an image. Basically I do this:

  1. I load an image (.png) and keep it in a bitmap:
    …
var loadedBitmap:Bitmap

…

function completeLoad (evt:Event):void{
	var loaderInfo:LoaderInfo = evt.target as LoaderInfo
	loadedBitmap = loaderInfo.content as Bitmap;
};
  1. Then I use copyPixels to take a portion of the image which has alpha channel
var bm:Bitmap;
bmd1.copyPixels(loadedBitmap.bitmapData, new Rectangle(0,0,64,64), new Point(0,0),null,null,true);
bm = new Bitmap(bmd1);
shapeContainer1.addChild(bm);
addChild(shapeContainer1);

If I render the whole image contained into loadedBitmap , I can see the transparent background.

var temp:MovieClip = new MovieClip ();
temp.addChild(loadedBitmap);
addChild(temp);

But using above procedure the background is shown black.

Any help?

Thanks in advance