<?xml version="1.0" encoding="utf-8"?>
<!-- http://blog.flexexamples.com/2008/09/09/rounding-the-corners-of-an-image-control-in-flex-using-a-mask/ -->
<mx:Application name="Image_mask_test"
        xmlns:mx="http://www.adobe.com/2006/mxml"
        layout="vertical"
        verticalAlign="middle"
        backgroundColor="white"
        initialize="init();">
 
    <mx:Script>
        <![CDATA[
            import mx.events.ResizeEvent;
 
            private var roundedMask:Sprite;
 
            private function init():void {
                roundedMask = new Sprite();
                canvas.rawChildren.addChild(roundedMask);
            }
 
            private function image_resize(evt:ResizeEvent):void {
                var w:Number = evt.currentTarget.width;
                var h:Number = evt.currentTarget.height;
                var cornerRadius:uint = 60;
                roundedMask.graphics.clear();
                roundedMask.graphics.beginFill(0xFF0000);
                roundedMask.graphics.drawRoundRect(0, 0,
                            w, h,
                            cornerRadius, cornerRadius);
                roundedMask.graphics.endFill();
                image.mask = roundedMask;
            }
        ]]>
    </mx:Script>
 
    <mx:Canvas id="canvas">
        <mx:Image id="image"
                source="http://www.helpexamples.com/flash/images/image1.jpg"
                resize="image_resize(event);">
        </mx:Image>
    </mx:Canvas>
 
</mx:Application>