package {
    import flash.display.*;
    import flash.events.*;
    import flash.net.*;
    import flash.geom.*;
    import flash.filters.*;
    
    public class @ax-actionscript-bitmap-GrayscaleDemo extends Sprite {
      private var loader:Loader;
  
      public function @ax-actionscript-bitmap-GrayscaleDemo () {
        loader = new Loader();
        loader.contentLoaderInfo.addEventListener(Event.INIT, 
                                                  initListener);
        loader.load(new URLRequest("actionscript-bitmap-assets-photo.jpg"));
      }
  
      private function initListener (e:Event):void {
        var loadedBitmapData:BitmapData = Bitmap(loader.content).bitmapData;
        toGrayscale(loadedBitmapData, 
                    loadedBitmapData,
                    loadedBitmapData.rect,
                    new Point(0,0));
        addChild(loader.content);
      }
  
      public function toGrayscale (source:BitmapData,
                                   dest:BitmapData,
                                   rect:Rectangle,
                                   point:Point):void {
        // Scale factors used to convert RGB to luminance, using weights 
        // based on Charles Poynton's color space FAQ, which cites
        // ITU-R Recommendation BT.709 as its source.
        // See: http://www.faqs.org/faqs/graphics/colorspace-faq/
        var redLuminance:Number = 0.212671;
        var greenLuminance:Number = 0.715160;
        var blueLuminance:Number = 0.072169;
  
        // Convert to grayscale by determining the average luminosity
        // of each pixel.
        var grayscaleFilter:ColorMatrixFilter = new ColorMatrixFilter(
                    new Array(redLuminance, greenLuminance, blueLuminance,0,0,
                              redLuminance, greenLuminance, blueLuminance,0,0,
                              redLuminance, greenLuminance, blueLuminance,0,0,
                                         0,              0,             0,1,0));
  
        dest.applyFilter(source, rect, point, grayscaleFilter);
      }
    }
  }