1. The pictures are each actually TWO pictures. The one that you see from close-up has the features in small, sharp markings that you see from close up but are difficult to focus on from a distance. The other picture in each double image is drawn with larger, bluntly defined markings that the eye can see from a distance, but are trumped by the sharp image at short range. The brain focuses its attention on edges. The close-up edges disappear from a distance, to be replaced by the edges of the blunt image.

2. The green dot is an after-image caused by the eye's accomodation to the pink dots. The eye always produces negative after images of anything that we look at for more than a couple of seconds just as soon as we look on a blank, uniform surface.