Вот код:

Код AS3:
package
{
import flash.display.Bitmap;
import flash.display.Loader;
import flash.display.Sprite;
import flash.events.Event;
import flash.events.MouseEvent;
import flash.net.URLRequest;
public class Main extends Sprite
{
private var loader:Loader;
public function Main()
{
loader = new Loader();
loader.contentLoaderInfo.addEventListener(Event.COMPLETE, onComplete);
loader.load(new URLRequest("img.jpg"));
stage.addEventListener(MouseEvent.MOUSE_MOVE, onMove);
}
private function onMove(e:MouseEvent):void
{
var color:uint = (loader.content as Bitmap).bitmapData.getPixel(mouseX, mouseY);
var r:uint = (color >> 16) & 0xFF;
var g:uint = (color >> 8) & 0xFF;
var b:uint = color & 0xFF;
var light:Number = (0.2126*r) + (0.7152*g) + (0.0722*b);
// от 0 черный до 255 белый
if (light >= 127.5) trace("светлый");
else trace("темный");
}
private function onComplete(e:Event):void
{
addChild(loader.content);
}
}
}