[ActionScript 3.0] AS3.0将图像的Alpha通道转换为黑白图像（复制通道方式）

import flash.display.BitmapData;
/**
 * 将图像的Alpha通道转换为黑白图像
 */
var p:Point = new Point(0,0);
var bmpd:BitmapData = new ImagePNG();//绑定的png图片
var channelBmpd:BitmapData = new BitmapData(bmpd.width,bmpd.height,true,0x00000000);
channelBmpd.fillRect(bmpd.rect, 0xff000000);
channelBmpd.copyChannel(bmpd, bmpd.rect, p, 8, 1);
channelBmpd.copyChannel(bmpd, bmpd.rect, p, 8, 2);
channelBmpd.copyChannel(bmpd, bmpd.rect, p, 8, 4);
var bmp = new Bitmap(channelBmpd);
this.addChild(bmp);