Flash ActionScript 3.0 apply color palette to BitmapData

applyColorPalette.as

var colorPalette = [0xFF5a3921, 0xFF6b8c42, 0xFF7bc67b, 0xFFffffb5];

function applyPalette(bitmap:BitmapData, palette:Array){

  bitmap.lock();

  for(var x = 0; x < bitmap.width; x++){
      for(var y = 0; y < bitmap.height; y++){

          var pixel = bitmap.getPixel(x, y);

          var c:uint = closestColor(pixel, palette);

          bitmap.setPixel(x, y, c);

      }
  }

  bitmap.unlock();
 
}

function colorDistance(color1:uint, color2:uint){
    
    var a = hex2rgb(color1);
    var b = hex2rgb(color2);
    
    return (Math.abs(a.r - b.r) + Math.abs(a.g - b.g) + Math.abs(a.b - b.b));
    
}

function closestColor(color:uint, palette:Array){
    
    var distance = 1000;
    var pickedColor = 0;
    
    for each(var c in palette){
        
        var d = colorDistance(color, c);
        
        if(d <= distance){ distance = d; pickedColor = c; }
        
    }
    
    return pickedColor;
    
}

function hex2rgb(color:uint):Object{

    var c:Object = {};
        c.r = color >> 16 & 0xFF;
        c.g = color >> 8 & 0xFF;
        c.b = color & 0xFF;

    return c;
    
}