size(300,300);
  background(0);
  fill(255);
  noStroke();
  smooth();

float xnoise = 0.0;
float ynoise = 0.0;
float inc = 0.08;
for (int y = 0; y < height; y++) {
  for (int x = 0; x < width; x++) {
    float gray = noise(xnoise, ynoise) * 255;
    stroke(gray, 510/gray);
    point(x,y);
    xnoise = xnoise + inc;
  }
  xnoise = 0;
  ynoise = ynoise + inc;
}