It's a visual illusion that is cuased by perceiving the size of objects samely without considering the distance from the viewer.
In the picture, the fishing people sitting/standing on the rim were, in fact, very close to the camera that took the picture, while the very small fishing man left was sitting far away from the camera. This picture does not provide enough distance cues, so our brain interprets the scene as ordinary size people fishing with a very small, tiny person.