​

function setup() {

  createCanvas(320, 240);

  // specify multiple formats for different browsers

  fingers = loadImage('moving.jpg');

  noStroke();

  fill(0);

}

​

function draw() {

  background(255);

  fingers.loadPixels();

  const stepSize = round(constrain(mouseX / 8, 6, 32));

  for (let y = 0; y < height; y += stepSize) {

    for (let x = 0; x < width; x += stepSize) {

      const i = y * width + x;

      const darkness = (255 - fingers.pixels[i * 4]) / 255;

      const radius = stepSize * darkness;

      ellipse(x, y, radius, radius);

    }

  }

  let fps = frameRate();

  text("FPS: " + fps.toFixed(2), 10, height - 10);

}

​