[Utes]

вот собственно и весь код:

<?xml version="1.0" encoding="utf-8"?>
<mx:Application xmlns:mx="http://www.adobe.com/2006/mxml"
	creationComplete="Init()">
	<mx:Script>
		<![CDATA[
			import src.ThreshholdSample;
			
			private function Init():void{
				new ThreshholdSample();
			}
		]]>
	</mx:Script>
	<mx:Image id="img1" width="350" height="205"/>
</mx:Application>

ThreshholdSample:

// ActionScript file
package src{
        import flash.display.Bitmap;
        import flash.display.BitmapData;
        import flash.display.Loader;
        import flash.display.Sprite;
        import flash.events.Event;
        import flash.geom.Point;
        import flash.net.URLRequest;
        import flash.system.ApplicationDomain;
        import flash.system.LoaderContext;
        import mx.core.Application;              

         // @author ivan.dembicki@gmail.com
        public class ThreshholdSample extends Sprite {

                public static function addTransparency(bmp : BitmapData, transparentColor : uint = 0) : BitmapData {
                        var newBmp:BitmapData = new BitmapData(bmp.width, bmp.height, true);
                        newBmp.draw(bmp);
                        newBmp.threshold(newBmp, bmp.rect, new Point(40,40), "==", transparentColor);
                        return newBmp;
                }
                
                private static const PICTURE_URL : String = "fishka_light_default.jpg";//"dimpiax.png";
                private static const TRANSPARENT_COLOR : uint = 0x000000;
                
                private const pictureLoader : Loader = new Loader();

                public function ThreshholdSample() {
                        initInstance();
                }
                
                private function initInstance() : void {
                        addChild(pictureLoader);
                        pictureLoader.contentLoaderInfo.addEventListener(Event.COMPLETE, onPictureLoaded);
                        const request : URLRequest = new URLRequest(PICTURE_URL);
                        const context : LoaderContext = new LoaderContext(false, ApplicationDomain.currentDomain);
                        pictureLoader.load(request, context);
                }
                
                private function onPictureLoaded(event : Event) : void {
                        const picture : Bitmap = pictureLoader.content as Bitmap;
                        const bmp : BitmapData = picture.bitmapData;
                        picture.bitmapData = addTransparency(bmp, TRANSPARENT_COLOR);
                        
                        Application.application.img1.source = picture;
                        
                }
                
        }
}