How this was created:
- located two similar images
- scaled, rotated, cropped, etc. so the pics were the same size and aligned
- sliced both into 256 pieces (16x16 grid of 17x17 blocks) using Paint Shop Pro's slice feature
- 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.
- used the web page created by Paint Shop Pro to display all 256 animated gifs