Generating clouds with perlin noise

Hi guys,

I am trying to generate some clouds with the perlin noise function.
Currently, i have the follow:

var channel:uint = 1 | 2 | 4 | 8;
var xpos:Number = Math.floor(Math.random()*100);
var ypos:Number = Math.floor(Math.random()*100);
var seed:Number = Math.floor(Math.random()*100);
var p:Point = new Point(xpos, ypos);
var offsetArray:Array = [p, p, p, p, p];

var bitmap:BitmapData = new BitmapData(300, 300, true, 0xFFFFFFFF);
bitmap.perlinNoise(300, 300, 10, seed, false, true,  channel, false, offsetArray);

With this, I get a cloud like bitmap, but i have all the colors in it (red blue and green). What i’d like to do is have a blue background and white clouds.

How would i go about doing that?