Despite the way this image looks, it is indeed a photograph. This is a picture of Camel Thorn trees in Namibia which was taken by Frans Lanting for National Geographic. The backdrop is actually a large dune and the spots are small patches of grass.
This stunning photograph caused a lot of controversy when it was first printed as many people did indeed believe it was a painting. This photo was featured in a an article written by Alexandra Fuller for National Geographic back in June of 2011.
You may have the same trouble I initially did trying to see the picture for what it is, a real photograph, but if you look at some of the changes in color that occur on the sand dune and the shadows that the patches of grass produce, then you may finally see past the “painting”.