creation

float xOff, yOff, zOff;
int step = 5;
PGraphics pg;

void setup() {
  size(540, 540, P2D);
  pg = createGraphics(width, height, P2D);
}

void draw() {
  background(255);
  xOff=0;
  for (int x=0; x<width; x+=step) {
    yOff=0;
    xOff += 0.05;
    for (int y=0; y<width; y+=step) {
      float ns = noise(xOff,yOff, zOff);
      float sz = map(ns, 0, 1, 0, step*2);
      noStroke();
      fill(0);
      if (ns<0.6)fill(255, 100, 0);
      if (ns>0.5) ellipse(x, y, sz, sz);
      yOff += 0.03;
    }
  }
  createMask();
  blend(pg,0,0,width, height, 0,0,width, height, MULTIPLY);
  zOff += 0.025;
  if (frameCount<=200) saveFrame("/Volumes/Anim/image-###.gif");
}

void createMask() {
  float sz = width*.75;
  pg.beginDraw();
  pg.background(0);
  pg.fill(255);
  pg.noStroke();
  pg.ellipse(width/2,height/2,sz,sz);
  pg.endDraw();
}