Evolution is heritable change. No single picture can show heritable change. However, a series of pictures of fossils can indeed show evolutionary change through time. For example, there are pictures of early hominids that have ape -like skulls, and later there are early archaic humans, and finally modern humans and Neanderthals.
You can also ask if human growth is real, why are there no pictures of it. Human growth (ontogeny) takes time, not as much time as evolution, but it takes more time than a single picture can show. We can take pictures periodically and show you evidence of it.