How this was created:
  1. located two similar images
  2. scaled, rotated, cropped, etc. so the pics were the same size and aligned
  3. sliced both into 256 pieces (16x16 grid of 17x17 blocks) using Paint Shop Pro's slice feature
  4. combined the 256 pairs of images into 256 animated gifs using Gifsicle. Each animated gif has a random delay to make the effect more random.
  5. used the web page created by Paint Shop Pro to display all 256 animated gifs