index.js

let sketch = function(p) {
  let n_size1 = 700;
  let n_size2 = 50;

  let nx, ny;

  p.setup = function() {
    const c = p.createCanvas(1200, 800);
    p.pixelDensity(1);
    p.noLoop();

    c.drop(gotFile);
  };

  p.draw = function() {
    p.fill(255);
    p.textSize(21);
    p.textAlign(p.CENTER);
    p.background('#888');
    p.text('Drop an image here!', p.width / 2, p.height / 2);
  };

  p.keyPressed = function() {
    if (p.keyCode === 80) p.saveCanvas('noisify', 'jpeg');
  };

  function gotFile(file) {
    if (file.type === 'image') {
      p.loadImage(file.data, imageLoaded);
    } else {
      console.log('Not an image file!');
    }
  }

  function imageLoaded(img) {
    p.loadPixels();
    img.loadPixels();

    nx = img.width;
    ny = img.height;

    const imgpixels = newArray(img.height).map((_, j) =>
      newArray(img.width).map((_, i) => {
        var loc = (i + j * img.width) * 4;
        return [img.pixels[loc + 0], img.pixels[loc + 1], img.pixels[loc + 2]];
      })
    );

    drawImage(imgpixels);
  }

  function drawImage(pixels) {
    p.noiseSeed(Math.random() * 999999);
    for (let i = 0; i < p.height; i++) {
      for (let j = 0; j < p.width; j++) {
        let cx = p.noise(i / n_size1, j / n_size1, 100) * nx;
        let cy = p.noise(i / n_size1, j / n_size1, 200) * ny;
        let dx = p.noise(i / n_size2, j / n_size2, 300) * (nx / 20);
        let dy = p.noise(i / n_size2, j / n_size2, 400) * (ny / 20);

        let c = pixels[p.floor(cy + dy)][p.floor(cx + dx)];
        p.stroke(...c);
        p.point(j, i);
      }
    }
  }
};
new p5(sketch);

function newArray(n, value) {
  n = n || 0;
  var array = new Array(n);
  for (var i = 0; i < n; i++) {
    array[i] = value;
  }
  return array;
}