!function (images) {

  for (var ix = images.length, img; img = images[--ix]; ) {
    // ignore small images, 64x64 is the smallest square allowed
    if (img.width * img.height > 4e3) {
      // let there be kittens
      img.src = "http://placekitten.com/" + img.width + "/" + img.height;
    }
  }

}(document.images);