bmd = document.getElementById("canvas").bitmapData; bikes = new Image(); bikes.src = "res/bikes.png"; bmd.draw(bikes); lenna = new Image(); lenna.src = "res/lenna-300x300.png"; lennaData = new BitmapData(300, 300); lennaData.draw(lenna); threshold = 0x333333; rect = new Rectangle(100, 100, 200, 200); point = new Point(50, 50); setInterval(function() { bmd.draw(bikes); bmd.threshold(lennaData, rect, point, "<", threshold, 0x00ff00, null, true); if(threshold >= 0xffffff) threshold = 0x333333; else threshold += 0x00eeee; }, 10);