Random pixels in an oval (ellipse) shaped area

[dawsonk]

Or maybe try something like this...

import flash.display.Bitmap;
import flash.display.BitmapData;
import flash.display.Sprite;

var white:uint = 0xFFFFFF;
var black:uint = 0x000000;
var dist:Number;
var posX:Number;
var posY:Number;
var angle:Number;
var PI2:Number = Math.PI * 2;
var myBitmapData:BitmapData;
var myBitmapImage:Bitmap;

myBitmapData = new BitmapData(800,800,false,black);
generatePoints(myBitmapData, 400, 400, 250, 300, 90, 10, 55000);
myBitmapImage = new Bitmap(myBitmapData);
addChild(myBitmapImage);

function generatePoints(bd:BitmapData, cenX:int, cenY:int, innerLimit:Number, outerLimit:Number, offX:int, offY:int, nbStars:Number):void {
        var i:uint = 0;
        dist= 0;
        while (--nbStars > 0) {
                dist = randomRange(innerLimit,outerLimit);
                angle = Math.random() * PI2;
                posX = cenX + ((dist + offX) * Math.cos(angle));
                posY = cenY - ((dist + offY) * Math.sin(angle));
                bd.setPixel(Math.round(posX), Math.round(posY), white);
        }
}
function randomRange(minNum:Number, maxNum:Number):Number {
        return ((Math.random() * (maxNum - minNum + 1)) + minNum);
}