It's a simple algorithm, and you could carry it out by hand in an image editor without much difficulty.

Just overlay N layers (the frames of your animation) on top of one another. For every Nth column of pixels, delete the next N-1 columns following it (in all layers). Then, for each layer at index X in the stack, translate the entire layer horizontally by X pixels.

Your overlay for viewing the animation is just a black opaque rectangle with every Nth column being deleted to reveal the image beneath.